Provided by: atop_2.6.0-2build1_amd64 bug

NAME

       atop - Advanced System & Process Monitor

SYNOPSIS

       Interactive Usage:

       atop   [-g|-m|-d|-n|-u|-p|-s|-c|-v|-o|-y|-Y]   [-C|-M|-D|-N|-A]  [-afFG1xR]  [-L  linelen]
       [-Plabel[,label]...]  [ interval [ samples ]]

       Writing and reading raw logfiles:

       atop -w rawfile [-a] [-S] [ interval [ samples ]]
       atop   -r    [    rawfile    ]    [-b    [YYYYMMDD]hhmm    ]    [-e    [YYYYMMDD]hhmm    ]
       [-g|-m|-d|-n|-u|-p|-s|-c|-v|-o|-y|-Y]     [-C|-M|-D|-N|-A]    [-fFG1xR]    [-L    linelen]
       [-Plabel[,label]...]

DESCRIPTION

       The program atop is an interactive monitor to view the load on a Linux system.   It  shows
       the  occupation of the most critical hardware resources (from a performance point of view)
       on system level, i.e. cpu, memory, disk and network.
       It also shows which processes are responsible for the indicated load with respect  to  cpu
       and  memory load on process level.  Disk load is shown per process if "storage accounting"
       is active in the kernel.  Network load is shown per process if the kernel module `netatop'
       has been installed.

       Every interval (default: 10 seconds) information is shown about the resource occupation on
       system level (cpu, memory, disks and network layers), followed  by  a  list  of  processes
       which  have  been  active  during  the  last  interval  (note that all processes that were
       unchanged during the last interval are not shown, unless the key 'a' has been  pressed  or
       unless  sorting  on  memory occupation is done).  If the list of active processes does not
       entirely fit on the screen, only the top  of  the  list  is  shown  (sorted  in  order  of
       activity).
       The  intervals  are repeated till the number of samples (specified as command argument) is
       reached, or till the key 'q' is pressed in interactive mode.

       When atop is started, it checks whether the standard output  channel  is  connected  to  a
       screen,  or  to  a  file/pipe. In the first case it produces screen control codes (via the
       ncurses library) and behaves interactively; in the second case  it  produces  flat  ASCII-
       output.

       In  interactive  mode,  the output of atop scales dynamically to the current dimensions of
       the screen/window.
       If the window is resized horizontally, columns will be added or removed automatically. For
       this  purpose,  every column has a particular weight. The columns with the highest weights
       that fit within the current width will be shown.
       If the window is resized vertically, lines of the process/thread list  will  be  added  or
       removed automatically.

       Furthermore  in  interactive  mode  the  output  of  atop  can  be  controlled by pressing
       particular keys.  However it is also possible to specify such key as flag on  the  command
       line.  In  that  case  atop switches to the indicated mode on beforehand; this mode can be
       modified again interactively. Specifying such  key  as  flag  is  especially  useful  when
       running  atop with output to a pipe or file (non-interactively).  These flags are the same
       as the keys that can be pressed in interactive mode (see section INTERACTIVE COMMANDS).
       Additional flags are available to support storage of atop-data in raw format (see  section
       RAW DATA STORAGE).

PROCESS ACCOUNTING

       With  every interval, atop reads the kernel administration to obtain information about all
       running processes.  However, it is likely that during the  interval  also  processes  have
       terminated.   These processes might have consumed system resources during this interval as
       well before they terminated.  Therefor, atop tries to read the process accounting  records
       that contain the accounting information of terminated processes and report these processes
       too.  Only when the process accounting mechanism in the kernel is  activated,  the  kernel
       writes such process accounting record to a file for every process that terminates.

       There  are various ways for atop to get access to the process accounting records (tried in
       this order):

       1.  When the environment variable ATOPACCT is set, it specifies the name  of  the  process
           accounting  file.   In  that  case,  process accounting for this file should have been
           activated on beforehand.  Before opening this file for reading, atop  drops  its  root
           privileges (if any).
           When  this  environment  variable  is  present  but  its  contents  is  empty, process
           accounting will not be used at all.

       2.  This is the preferred way of handling process accounting records!
           When the atopacctd daemon is active, it has activated the process accounting mechanism
           in  the  kernel and transfers to original accounting records to shadow files.  In that
           case, atop drops its root privileges and opens the current shadow file for reading.
           This way is preferred, because the atopacctd daemon  maintains  full  control  of  the
           sizes  of  the original process accounting file (written by the kernel) and the shadow
           files (read by the atop processes). For further information, refer  to  the  atopacctd
           man page.

       3.  When  the  atopacctd  daemon  is  not  active, atop verifies if the process accounting
           mechanism has been switched on via the separate psacct  package.  In  that  case,  the
           files  /var/account/pacct, /var/log/account/pacct and /var/log/pacct are considered to
           be in use as process accounting file and atop opens the respective file for reading.

       4.  As a last possibility, atop itself tries to activate the process accounting  mechanism
           (requires  root  privileges) using the file /var/cache/atop.d/atop.acct (to be written
           by the kernel, to be read by atop itself). Process accounting remains active  as  long
           as  at  least one atop process is alive.  Whenever the last atop process stops (either
           by pressing `q' or by `kill -15'), it deactivates  the  process  accounting  mechanism
           again.  Therefor  you should never terminate atop by `kill -9', because then it has no
           chance to stop process accounting.  As a result, the accounting file may consume a lot
           of disk space after a while.
           To  avoid that the process accounting file consumes too much disk space, atop verifies
           at the end of every sample if the size of the process accounting file exceeds 200  MiB
           and  if  this  atop process is the only one that is currently using the file.  In that
           case the file is truncated to a size of zero.

           Notice that root-privileges are required to switch on/off process  accounting  in  the
           kernel.  You  can  start  atop as a root user or specify setuid-root privileges to the
           executable file.  In the latter case, atop switches on process  accounting  and  drops
           the root-privileges again.
           If atop does not run with root-privileges, it does not show information about finished
           processes.  It indicates this situation with the message message `no procacct` in  the
           top-right corner (instead of the counter that shows the number of exited processes).

       When during one interval a lot of processes have finished, atop might grow tremendously in
       memory when reading all process accounting records at the end of the  interval.  To  avoid
       such excessive growth, atop will never read more than 50 MiB with process information from
       the  process  accounting  file  per  interval  (approx.  70000  finished  processes).   In
       interactive mode a warning is given whenever processes have been skipped for this reason.

COLORS

       For the resource consumption on system level, atop uses colors to indicate that a critical
       occupation percentage has been (almost) reached.  A critical occupation  percentage  means
       that  is  likely  that  this  load  causes a noticeable negative performance influence for
       applications using this resource. The critical percentage depends on the type of resource:
       e.g.  the  performance  influence  of  a  disk with a busy percentage of 80% might be more
       noticeable for applications/user than a CPU with a busy percentage of 90%.
       Currently atop uses the following default values to calculate a  weighted  percentage  per
       resource:

        Processor
            A busy percentage of 90% or higher is considered `critical'.

        Disk
            A busy percentage of 70% or higher is considered `critical'.

        Network
            A  busy  percentage  of  90%  or  higher  for  the load of an interface is considered
            `critical'.

        Memory
            An  occupation  percentage  of  90%  is  considered  `critical'.   Notice  that  this
            occupation  percentage is the accumulated memory consumption of the kernel (including
            slab) and all processes; the memory for the page cache (`cache'  and  `buff'  in  the
            MEM-line) and the reclaimable part of the slab (`slrec`) is not implied!
            If  the  number  of pages swapped out (`swout' in the PAG-line) is larger than 10 per
            second, the memory resource is considered `critical'.  A value  of  at  least  1  per
            second is considered `almost critical'.
            If  the  committed  virtual memory exceeds the limit (`vmcom' and `vmlim' in the SWP-
            line), the SWP-line is colored due to overcommitting the system.

        Swap
            An occupation percentage of 80% is considered `critical' because swap space might  be
            completely exhausted in the near future; it is not critical from a performance point-
            of-view.

       These default values can be modified in the configuration file (see separate  man-page  of
       atoprc).

       When  a  resource exceeds its critical occupation percentage, the concerning values in the
       screen line are colored red by default.
       When a resource exceeded (default) 80%  of  its  critical  percentage  (so  it  is  almost
       critical),  the  concerning  values  in  the screen line are colored cyan by default. This
       `almost critical percentage' (one  value  for  all  resources)  can  be  modified  in  the
       configuration file (see separate man-page of atoprc).
       The  default  colors  red  and cyan can be modified in the configuration file as well (see
       separate man-page of atoprc).

       With the key 'x' (or flag -x), the use of colors can be suppressed.

NETATOP MODULE

       Per-process and per-thread network activity can be measured by the netatop kernel  module.
       You  can download this kernel module from the website (mentioned at the end of this manual
       page) and install it on your system if the kernel version is 2.6.24 or newer.
       When atop gathers counters for a new interval,  it  verifies  if  the  netatop  module  is
       currently  active.  If so, atop obtains the relevant network counters from this module and
       shows the number of sent and received packets per process/thread in  the  generic  screen.
       Besides, detailed counters can be requested by pressing the `n' key.
       When  the  netatopd  daemon  is  running  as well, atop also reads the network counters of
       exited processes that are logged by this daemon (comparable with process accounting).

       More information about the optional netatop kernel module and the netatopd daemon  can  be
       found  in  the concerning man-pages and on the website mentioned at the end of this manual
       page.

GPU STATISTICS GATHERING

       GPU statistics can be gathered by atopgpud which is  a  separate  data  collection  daemon
       process.  It gathers cumulative utilization counters of every Nvidia GPU in the system, as
       well as utilization counters of every process that uses a GPU.  When atop notices that the
       daemon is active, it reads these GPU utilization counters with every interval.

       The  atopgpud  daemon is written in Python, so a Python interpreter should be installed on
       the target system. The Python code of the daemon is compatible with Python version  2  and
       version  3.  For the gathering of the statistics, the pynvml module is used by the daemon.
       Be sure that this module is installed on the target system before activating  the  daemon,
       by  running the command as root pip (the command pip might be exchanged by pip3 in case of
       Python3):

         pip install nvidia-ml-py

       The atopgpud daemon is installed by default as part of the atop package,  but  it  is  not
       automatically enabled.  The daemon can be enabled and started now by running the following
       commands (as root):

         systemctl enable atopgpu
         systemctl start atopgpu

       Find a description about the utilization counters in the section OUTPUT DESCRIPTION.

INTERACTIVE COMMANDS

       When running atop interactively (no output redirection), keys can be  pressed  to  control
       the  output.  In  general,  lower  case keys can be used to show other information for the
       active processes and upper case keys can be used to influence the sort order of the active
       process/thread list.

       g    Show generic output (default).

            Per process the following fields are shown in case of a window-width of 80 positions:
            process-id, cpu consumption during the last interval in system  and  user  mode,  the
            virtual and resident memory growth of the process.

            The subsequent columns depend on the used kernel:
            When  the  kernel  supports  "storage  accounting" (>= 2.6.20), the data transfer for
            read/write on disk, the status and exit code are shown for each  process.   When  the
            kernel  does not support "storage accounting", the username, number of threads in the
            thread group, the status and exit code are shown.
            When the kernel module 'netatop' is loaded, the data  transfer  for  send/receive  of
            network packets is shown for each process.
            The last columns contain the state, the occupation percentage for the chosen resource
            (default: cpu) and the process name.

            When more than 80 positions are available, other information is added.

       m    Show memory related output.

            Per process the following fields are shown in case of a window-width of 80 positions:
            process-id, minor and major memory faults, size of virtual shared text, total virtual
            process size, total resident process size, virtual and resident  growth  during  last
            interval, memory occupation percentage and process name.

            When more than 80 positions are available, other information is added.

            For  memory consumption, always all processes are shown (also the processes that were
            not active during the interval).

       d    Show disk-related output.

            When "storage accounting" is active in the kernel, the following  fields  are  shown:
            process-id,  amount of data read from disk, amount of data written to disk, amount of
            data that was  written  but  has  been  withdrawn  again  (WCANCL),  disk  occupation
            percentage and process name.

       n    Show network related output.

            Per process the following fields are shown in case of a window-width of 80 positions:
            process-id, thread-id, total bandwidth for received packets, total bandwidth for sent
            packets,  number of received TCP packets with the average size per packet (in bytes),
            number of sent TCP packets with the average size per packet  (in  bytes),  number  of
            received  UDP packets with the average size per packet (in bytes), number of sent UDP
            packets with  the  average  size  per  packet  (in  bytes),  the  network  occupation
            percentage and process name.
            This information can only be shown when kernel module `netatop' is installed.

            When more than 80 positions are available, other information is added.

       s    Show scheduling characteristics.

            Per process the following fields are shown in case of a window-width of 80 positions:
            process-id, number of threads in state 'running' (R),  number  of  threads  in  state
            'interruptible  sleeping'  (S), number of threads in state 'uninterruptible sleeping'
            (D), scheduling policy (normal timesharing,  realtime  round-robin,  realtime  fifo),
            nice value, priority, realtime priority, current processor, status, exit code, state,
            the occupation percentage for the chosen resource and the process name.

            When more than 80 positions are available, other information is added.

       v    Show various process characteristics.

            Per process the following fields are shown in case of a window-width of 80 positions:
            process-id,  user  name and group, start date and time, status (e.g. exit code if the
            process has finished), state, the occupation percentage for the chosen  resource  and
            the process name.

            When more than 80 positions are available, other information is added.

       c    Show the command line of the process.

            Per process the following fields are shown: process-id, the occupation percentage for
            the chosen resource and the command line including arguments.

       e    Show GPU utilization.

            Per process at least the following fields are shown: process-id, range of GPU numbers
            on  which  the  process  currently runs, GPU busy percentage on all GPUs, memory busy
            percentage (i.e. read and write accesses on memory) on all GPUs, memory occupation at
            the  moment  of  the  sample,  average  memory  occupation during the sample, and GPU
            percentage.

            When the atopgpud daemon does not run with root privileges, the GPU  busy  percentage
            and the memory busy percentage are not available on process level.  In that case, the
            GPU percentage on process level reflects the GPU memory occupation instead of the GPU
            busy percentage (which is preferred).

       o    Show the user-defined line of the process.

            In  the  configuration  file  the  keyword  ownprocline  can  be  specified  with the
            description of a user-defined output-line.
            Refer to the man-page of atoprc for a detailed description.

       y    Show the individual threads within a process (toggle).

            Single-threaded processes are still shown as one line.
            For multi-threaded processes, one line represents the process while additional  lines
            show  the  activity  per  individual  thread (in a different color). Depending on the
            option 'a' (all or active toggle), all threads are shown or  only  the  threads  that
            were  active  during  the last interval.  Depending on the option 'Y' (sort threads),
            the threads per process will be sorted on the chosen sort criterium or not.
            Whether this key is active or not can be seen in the header line.

       Y    Sort the threads per process when combined with option 'y' (toggle).

       u    Show the process activity accumulated per user.

            Per user the following fields are shown: number of  processes  active  or  terminated
            during  last  interval  (or  in  total if combined with command `a'), accumulated cpu
            consumption during last interval in system and user mode,  the  current  virtual  and
            resident  memory  space consumed by active processes (or all processes of the user if
            combined with command `a').
            When "storage accounting" is active in the kernel, the  accumulated  read  and  write
            throughput  on  disk  is shown.  When the kernel module `netatop' has been installed,
            the number of received and sent network packets are shown.
            The last columns  contain  the  accumulated  occupation  percentage  for  the  chosen
            resource (default: cpu) and the user name.

       p    Show the process activity accumulated per program (i.e. process name).

            Per  program the following fields are shown: number of processes active or terminated
            during last interval (or in total if combined  with  command  `a'),  accumulated  cpu
            consumption  during  last  interval  in system and user mode, the current virtual and
            resident memory space consumed by active processes (or all processes of the  user  if
            combined with command `a').
            When  "storage  accounting"  is  active in the kernel, the accumulated read and write
            throughput on disk is shown.  When the kernel module `netatop'  has  been  installed,
            the number of received and sent network packets are shown.
            The  last  columns  contain  the  accumulated  occupation  percentage  for the chosen
            resource (default: cpu) and the program name.

       j    Show the process activity accumulated per Docker container.

            Per container  the  following  fields  are  shown:  number  of  processes  active  or
            terminated  during  last  interval  (or  in  total  if  combined  with  command `a'),
            accumulated cpu consumption during last interval in system and user mode, the current
            virtual  and  resident memory space consumed by active processes (or all processes of
            the user if combined with command `a').
            When "storage accounting" is active in the kernel, the  accumulated  read  and  write
            throughput  on  disk  is shown.  When the kernel module `netatop' has been installed,
            the number of received and sent network packets are shown.
            The last columns  contain  the  accumulated  occupation  percentage  for  the  chosen
            resource (default: cpu) and the Docker container id (CID).

       C    Sort  the  current  list in the order of cpu consumption (default).  The one-but-last
            column changes to ``CPU''.

       E    Sort the current list in the order of GPU utilization (preferred, but only applicable
            when  the  atopgpud  daemon  runs  under  root privileges) or the order of GPU memory
            occupation).  The one-but-last column changes to ``GPU''.

       M    Sort the current list in the order of resident memory consumption.  The  one-but-last
            column  changes  to ``MEM''. In case of sorting on memory, the full process list will
            be shown (not only the active processes).

       D    Sort the current list in the order of disk accesses issued.  The one-but-last  column
            changes to ``DSK''.

       N    Sort  the  current list in the order of network bandwidth (received and transmitted).
            The one-but-last column changes to ``NET''.

       A    Sort the current list automatically in the order of the  most  busy  system  resource
            during  this  interval.   The  one-but-last  column  shows either ``ACPU'', ``AMEM'',
            ``ADSK'' or ``ANET'' (the preceding 'A' indicates automatic sorting-order).  The most
            busy  resource is determined by comparing the weighted busy-percentages of the system
            resources, as described earlier in the section COLORS.
            This option remains valid until another sorting-order is explicitly selected again.
            A sorting-order for disk is only possible when "storage  accounting"  is  active.   A
            sorting-order  for  network  is  only  possible  when  the kernel module `netatop' is
            loaded.

       Miscellaneous interactive commands:

       ?    Request for help information (also the key 'h' can be pressed).

       V    Request for version information (version number and date).

       R    Gather and calculate the proportional set size of processes (toggle).   Gathering  of
            all  values  that  are  needed  to  calculate  the PSIZE of a process is a very time-
            consuming task, so this key should only be active when analyzing the resident  memory
            consumption of processes.

       W    Get  the  WCHAN  per  thread (toggle).  Gathering of the WCHAN string per thread is a
            relatively time-consuming task, so this key should only be made active when analyzing
            the reason for threads to be in sleep state.

       x    Suppress colors to highlight critical resources (toggle).
            Whether this key is active or not can be seen in the header line.

       z    The pause key can be used to freeze the current situation in order to investigate the
            output on the screen. While atop is paused, the keys described above can  be  pressed
            to  show  other  information about the current list of processes.  Whenever the pause
            key is pressed again, atop will continue with a next sample.

       i    Modify the interval timer (default: 10  seconds).  If  an  interval  timer  of  0  is
            entered,  the  interval  timer is switched off. In that case a new sample can only be
            triggered manually by pressing the key 't'.

       t    Trigger a new sample manually. This key can be pressed if the current  sample  should
            be  finished  before  the  timer has exceeded, or if no timer is set at all (interval
            timer defined as 0). In the latter case atop can be used as a  stopwatch  to  measure
            the  load  being  caused  by a particular application transaction, without knowing on
            beforehand how many seconds this transaction will last.

            When viewing the contents of a raw file this key can be used to show the next  sample
            from the file. This key can also be used when viewing raw data via a pipe.

       T    When  viewing  the  contents  of a raw file this key can be used to show the previous
            sample from the file, however not when reading raw data from a pipe.

       b    When viewing the contents of a raw file, this key can be used to branch to a  certain
            timestamp  within  the file either forward or backward.  When viewing raw data from a
            pipe only forward branches are possible.

       r    Reset all counters to zero to see the system and process activity since boot again.

            When viewing the contents of a raw file, this key  can  be  used  to  rewind  to  the
            beginning of the file again (except when reading raw data from a pipe).

       U    Specify  a  search  string for specific user names as a regular expression.  From now
            on, only (active) processes will be shown from  a  user  which  matches  the  regular
            expression.   The  system  statistics  are  still  system  wide.  If the Enter-key is
            pressed without specifying a name, (active) processes of  all  users  will  be  shown
            again.
            Whether this key is active or not can be seen in the header line.

       I    Specify  a  list  with  one or more PIDs to be selected.  From now on, only processes
            will be shown with a PID which matches one of the given list.  The system  statistics
            are  still  system  wide.   If the Enter-key is pressed without specifying a PID, all
            (active) processes will be shown again.
            Whether this key is active or not can be seen in the header line.

       P    Specify a search string for specific process names as a regular expression.  From now
            on,  only  processes  will be shown with a name which matches the regular expression.
            The system statistics are still system wide.  If the  Enter-key  is  pressed  without
            specifying a name, all (active) processes will be shown again.
            Whether this key is active or not can be seen in the header line.

       /    Specify  a specific command line search string as a regular expression.  From now on,
            only processes  will  be  shown  with  a  command  line  which  matches  the  regular
            expression.   The  system  statistics  are  still  system  wide.  If the Enter-key is
            pressed without specifying a string, all (active) processes will be shown again.
            Whether this key is active or not can be seen in the header line.

       J    Specify a Docker container id of 12 (hexadecimal)  characters.   From  now  on,  only
            processes will be shown that run in that specific Docker container (CID).  The system
            statistics are still system wide.  If the Enter-key is pressed without  specifying  a
            container id, all (active) processes will be shown again.
            Whether this key is active or not can be seen in the header line.

       S    Specify  search  strings  for  specific logical volume names, specific disk names and
            specific network interface names. All search strings are  interpreted  as  a  regular
            expressions.   From  now  on,  only  those  system resources are shown that match the
            concerning regular expression.  If the Enter-key  is  pressed  without  specifying  a
            search string, all (active) system resources of that type will be shown again.
            Whether this key is active or not can be seen in the header line.

       a    The  `all/active'  key  can  be  used to toggle between only showing/accumulating the
            processes that were active during the last interval (default) or showing/accumulating
            all processes.
            Whether this key is active or not can be seen in the header line.

       G    By  default,  atop  shows/accumulates  the processes that are alive and the processes
            that   are   exited   during   the   last   interval.   With   this   key   (toggle),
            showing/accumulating the processes that are exited can be suppressed.
            Whether this key is active or not can be seen in the header line.

       f    Show  a  fixed  (maximum)  number  of header lines for system resources (toggle).  By
            default only the lines are  shown  about  system  resources  (CPUs,  paging,  logical
            volumes,  disks,  network  interfaces)  that  really have been active during the last
            interval.  With this key you can force atop to show lines of  inactive  resources  as
            well.
            Whether this key is active or not can be seen in the header line.

       F    Suppress  sorting  of  system resources (toggle).  By default system resources (CPUs,
            logical volumes, disks, network interfaces) are sorted on utilization.
            Whether this key is active or not can be seen in the header line.

       1    Show relevant counters as an average per second (in the format `..../s')  instead  of
            as a total during the interval (toggle).
            Whether this key is active or not can be seen in the header line.

       l    Limit the number of system level lines for the counters per-cpu, the active disks and
            the network interfaces.  By default lines are shown of all CPUs,  disks  and  network
            interfaces which have been active during the last interval.  Limiting these lines can
            be useful on systems with huge number CPUs, disks or interfaces in order to  be  able
            to run atop on a screen/window with e.g. only 24 lines.
            For   all   mentioned  resources  the  maximum  number  of  lines  can  be  specified
            interactively. When using the flag -l the maximum number of per-cpu lines is  set  to
            0, the maximum number of disk lines to 5 and the maximum number of interface lines to
            3.  These values can be modified again in interactive mode.

       k    Send a signal to an active process (a.k.a. kill a process).

       q    Quit the program.

       PgDn Show the next page of the process/thread list.
            With the arrow-down key the list can be scrolled downwards with single lines.

       ^F   Show the next page of the process/thread list (forward).
            With the arrow-down key the list can be scrolled downwards with single lines.

       PgUp Show the previous page of the process/thread list.
            With the arrow-up key the list can be scrolled upwards with single lines.

       ^B   Show the previous page of the process/thread list (backward).
            With the arrow-up key the list can be scrolled upwards with single lines.

       ^L   Redraw the screen.

RAW DATA STORAGE

       In order to store system and process level statistics  for  long-term  analysis  (e.g.  to
       check  the  system  load  and the active processes running yesterday between 3:00 and 4:00
       PM), atop can store the system and process level statistics in compressed binary format in
       a  raw file with the flag -w followed by the filename.  If this file already exists and is
       recognized as a raw data file, atop will append new samples to the file (starting  with  a
       sample  which  reflects  the  activity since boot); if the file does not exist, it will be
       created.
       All information about processes and threads is stored in the raw file.
       The interval (default: 10 seconds) and number of samples (default: infinite) can be passed
       as  last  arguments. Instead of the number of samples, the flag -S can be used to indicate
       that atop should finish anyhow before midnight.

       A raw file can be read and visualized again with the flag -r followed by the filename.  If
       no  filename is specified, the file /var/log/atop/atop_YYYYMMDD is opened for input (where
       YYYYMMDD are digits representing the current date).  If a filename  is  specified  in  the
       format  YYYYMMDD  (representing  any  valid date), the file /var/log/atop/atop_YYYYMMDD is
       opened.  If a filename with the symbolic name y is specified, yesterday's daily logfile is
       opened  (this  can  be repeated so 'yyyy' indicates the logfile of four days ago).  If the
       filename - is used, stdin will be read.
       The samples from the file can be viewed interactively by using the key  't'  to  show  the
       next  sample,  the  key  'T'  to  show  the  previous  sample,  the key 'b' to branch to a
       particular time or the key 'r' to rewind to the begin of the file.
       When output is redirected to a file or pipe, atop prints all samples in plain  ASCII.  The
       default  line  length  is  80  characters  in  that  case; with the flag -L followed by an
       alternate line length, more (or less) columns will be shown.
       With the flag -b (begin time) and/or -e (end time) followed by a time argument of the form
       [YYYYMMDD]hhmm, a certain time period within the raw file can be selected.

       Every  day  at  midnight  atop  is  restarted  to write compressed binary data to the file
       /var/log/atop/atop_YYYYMMDD with an interval of 10 minutes by default.
       Furthermore all raw files are removed that are older than 28 days (by default).
       The mentioned default values can be overruled in the  file  /etc/default/atop  that  might
       contain  other  values for LOGOPTS (by default without any flag), LOGINTERVAL (in seconds,
       by default 600), LOGGENERATIONS (in days, by default 28), and LOGPATH (directory in  which
       logfiles are stored).

       Unfortunately, it is not always possible to keep the format of the raw files compatible in
       newer versions of atop especially when  lots  of  new  counters  have  to  be  maintained.
       Therefore,  the program atopconvert is installed to convert a raw file created by an older
       version of atop to a raw file that can be read by a newer version of  atop  (see  the  man
       page of atopconvert for more details).

OUTPUT DESCRIPTION

       The  first  sample  shows  the  system  level activity since boot (the elapsed time in the
       header shows the time since boot).  Note that particular counters could have reached their
       maximum value (several times) and started by zero again, so do not rely on these figures.

       For  every  sample  atop  first  shows  the  lines  related to system level activity. If a
       particular system resource has not been used during the interval, the entire line  related
       to  this  resource  is  suppressed.  So the number of system level lines may vary for each
       sample.
       After that a list is shown of processes which have been active during the  last  interval.
       This  list  is  by default sorted on cpu consumption, but this order can be changed by the
       keys which are previously described.

       If values have to be shown by atop which do not fit in the column width, another format is
       used.  If  e.g. a cpu-consumption of 233216 milliseconds should be shown in a column width
       of 4 positions, it is shown as `233s' (in seconds).  For  large  memory  figures,  another
       unit  is  chosen if the value does not fit (Mb instead of Kb, Gb instead of Mb, Tb instead
       of Gb, ...).  For other values, a kind of exponent notation is used (value 123456789 shown
       in a column of 5 positions gives 123e6).

OUTPUT DESCRIPTION - SYSTEM LEVEL

       The system level information consists of the following output lines:

       PRC  Process and thread level totals.
            This  line  contains  the  total cpu time consumed in system mode (`sys') and in user
            mode (`user'), the total number of processes present at this  moment  (`#proc'),  the
            total  number  of  threads  present  at  this  moment  in  state `running' (`#trun'),
            `sleeping interruptible' (`#tslpi') and `sleeping  uninterruptible'  (`#tslpu'),  the
            number  of zombie processes (`#zombie'), the number of clone system calls (`clones'),
            and the number of processes that ended during the  interval  (`#exit')  when  process
            accounting  is  used.  Instead  of  `#exit` the last column may indicate that process
            accounting could not be activated (`no procacct`).
            If the screen-width does not allow all of these counters, only a relevant  subset  is
            shown.

       CPU  CPU utilization.
            At least one line is shown for the total occupation of all CPUs together.
            In case of a multi-processor system, an additional line is shown for every individual
            processor (with `cpu' in lower case), sorted on activity. Inactive CPUs will  not  be
            shown by default.  The lines showing the per-cpu occupation contain the cpu number in
            the field combined with the wait percentage.

            Every line contains the percentage of cpu time spent in kernel  mode  by  all  active
            processes  (`sys'), the percentage of cpu time consumed in user mode (`user') for all
            active processes (including processes running with a nice value  larger  than  zero),
            the  percentage  of  cpu time spent for interrupt handling (`irq') including softirq,
            the percentage of unused cpu time while  no  processes  were  waiting  for  disk  I/O
            (`idle'),  and  the  percentage  of  unused  cpu  time while at least one process was
            waiting for disk I/O (`wait').
            In case of per-cpu occupation, the cpu number and the wait percentage (`w') for  that
            cpu.  The number of lines showing the per-cpu occupation can be limited.

            For virtual machines, the steal-percentage (`steal') shows the percentage of cpu time
            stolen by other virtual machines running on the same hardware.
            For physical machines hosting one or  more  virtual  machines,  the  guest-percentage
            (`guest')  shows the percentage of cpu time used by the virtual machines. Notice that
            this percentage overlaps the user percentage!

            When PMC performance monitoring counters are supported by the CPU and the kernel (and
            atop  runs with root privileges), the number of instructions per CPU cycle (`ipc') is
            shown.  The first sample always shows the value 'initial', because the  counters  are
            just activated at the moment that atop is started.
            When  the CPU busy percentage is high and the IPC is less than 1.0, it is likely that
            the CPU is frequently waiting for memory access during instruction execution  (larger
            CPU  caches  or faster memory might be helpful to improve performance).  When the CPU
            busy percentage is high and the IPC is greater than 1.0, it is likely that the CPU is
            instruction-bound (more/faster cores might be helpful to improve performance).
            Furthermore,  per  CPU  the effective number of cycles (`cycl') is shown.  This value
            can reach the current CPU frequency if such CPU is 100% busy.  When an  idle  CPU  is
            halted,  the  number of effective cycles can be (considerably) lower than the current
            frequency.
            Notice that the average instructions per cycle and number of cycles is shown  in  the
            CPU line for all CPUs.
            Beware  that  reading  the cycle counter in virtual machines (guests) might introduce
            performance delays. Therefore this metric is by default disabled in virtual machines.
            However,  with  the  keyword  'perfevents'  in  the  atoprc  file  this metric can be
            explicitly set to 'enable' or 'disable' (see separate man-page of atoprc).
            See also: http://www.brendangregg.com/blog/2017-05-09/cpu-utilization-is-wrong.html

            In case of frequency scaling, all previously mentioned CPU percentages  are  relative
            to  the  used  scaling  of the CPU during the interval.  If a CPU has been active for
            e.g. 50% in user mode during the interval while the frequency scaling of that CPU was
            40%, only 20% of the full capacity of the CPU has been used in user mode.
            In  case  that  the kernel module `cpufreq_stats' is active (after issueing `modprobe
            cpufreq_stats'), the average frequency (`avgf') and the  average  scaling  percentage
            (`avgscal')  is  shown.  Otherwise  the  current  frequency  (`curf') and the current
            scaling percentage (`curscal') is shown at the  moment  that  the  sample  is  taken.
            Notice  that  average  values for frequency and scaling are shown in the CPU line for
            every CPU.
            Frequency scaling statistics are only gathered for systems with maximum 8 CPUs, since
            gathering of these values per CPU is very time consuming.

            If  the  screen-width does not allow all of these counters, only a relevant subset is
            shown.

       CPL  CPU load information.
            This line contains the load average figures reflecting the number of threads that are
            available  to  run  on a CPU (i.e. part of the runqueue) or that are waiting for disk
            I/O. These figures are averaged over 1 (`avg1'), 5 (`avg5') and 15 (`avg15') minutes.
            Furthermore the number of context switches (`csw'), the number of serviced interrupts
            (`intr') and the number of available CPUs are shown.

            If  the  screen-width does not allow all of these counters, only a relevant subset is
            shown.

       GPU  GPU utilization (Nvidia).
            Read the section GPU STATISTICS GATHERING in this document to find the details  about
            the activation of the atopgpud daemon.

            In  the  first  column  of  every line, the bus-id (last nine characters) and the GPU
            number are shown.  The subsequent columns show the percentage of  time  that  one  or
            more  kernels  were  executing  on  the  GPU (`gpubusy'), the percentage of time that
            global (device)  memory  was  being  read  or  written  (`membusy'),  the  occupation
            percentage  of memory (`memocc'), the total memory (`total'), the memory being in use
            at the moment of the sample (`used'), the average memory  being  in  use  during  the
            sample  time (`usavg'), the number of processes being active on the GPU at the moment
            of the sample (`#proc'), and the type of GPU.

            If the screen-width does not allow all of these counters, only a relevant  subset  is
            shown.
            The number of lines showing the GPUs can be limited.

       MEM  Memory occupation.
            This  line contains the total amount of physical memory (`tot'), the amount of memory
            which is currently free (`free'), the amount of memory in use as page cache including
            the  total  resident  shared  memory  (`cache'), the amount of memory within the page
            cache that has to be flushed to  disk  (`dirty'),  the  amount  of  memory  used  for
            filesystem  meta  data  (`buff'),  the amount of memory being used for kernel mallocs
            (`slab'), the amount of slab memory that is reclaimable (`slrec'), the resident  size
            of  shared  memory  including  tmpfs  (`shmem`),  the  resident size of shared memory
            (`shrss`) the amount of shared memory that is currently swapped (`shswp`), the amount
            of  memory that is currently claimed by vmware's balloon driver (`vmbal`), the amount
            of memory that is currently claimed by the ARC (cache) of ZFSonlinux  (`zfarc`),  the
            amount  of  memory  that  is claimed for huge pages (`hptot`), and the amount of huge
            page memory that is really in use (`hpuse`).

            If the screen-width does not allow all of these counters, only a relevant  subset  is
            shown.

       SWP  Swap occupation and overcommit info.
            This line contains the total amount of swap space on disk (`tot'), the amount of free
            swap space (`free') and the size of the swap cache (`swcac').
            Furthermore the committed virtual memory space (`vmcom') and the maximum limit of the
            committed  space  (`vmlim', which is by default swap size plus 50% of memory size) is
            shown.  The committed space is the reserved virtual  space  for  all  allocations  of
            private  memory  space  for processes. The kernel only verifies whether the committed
            space   exceeds   the   limit   if   strict   overcommit   handling   is   configured
            (vm.overcommit_memory is 2).

       PAG  Paging frequency.
            This  line  contains  the  number of scanned pages (`scan') due to the fact that free
            memory drops below a particular threshold and the number times that the kernel  tries
            to reclaim pages due to an urgent need (`stall').
            Also  the  number  of  memory  pages the system read from swap space (`swin') and the
            number of memory pages the system wrote to swap space (`swout') are shown.

       PSI  Pressure Stall Information.
            This line contains percentages about resource pressure related  to  CPU,  memory  and
            I/O.  Certain  percentages  refer  to 'some' meaning that some processes/threads were
            delayed due to resource overload. Other percentages refer to 'full' meaning a loss of
            overall throughput due to resource overload.
            The  values  `cpusome', `memsome', `memfull', `iosome' and `iofull' show the pressure
            percentage during the entire interval.
            The values `cs' (cpu some), `ms' (memory some), `mf' (memory full), `is'  (I/O  some)
            and  `if'  (I/O  full)  each  show  three  percentages separated by slashes: pressure
            percentage over the last 10, 60 and 300 seconds.

       LVM/MDD/DSK
            Logical volume/multiple device/disk utilization.
            Per active unit one line is produced, sorted on unit activity.  Such line  shows  the
            name  (e.g.  VolGroup00-lvtmp  for a logical volume or sda for a hard disk), the busy
            percentage i.e. the portion  of  time  that  the  unit  was  busy  handling  requests
            (`busy'),  the  number of read requests issued (`read'), the number of write requests
            issued (`write'), the number of KiBytes per read (`KiB/r'), the number of KiBytes per
            write (`KiB/w'), the number of MiBytes per second throughput for reads (`MBr/s'), the
            number of MiBytes per second throughput for writes (`MBw/s'), the average queue depth
            (`avq') and the average number of milliseconds needed by a request (`avio') for seek,
            latency and data transfer.
            If the screen-width does not allow all of these counters, only a relevant  subset  is
            shown.

            The number of lines showing the units can be limited per class (LVM, MDD or DSK) with
            the 'l' key or statically (see separate man-page of atoprc).  By specifying the value
            0 for a particular class, no lines will be shown any more for that class.

       NFM  Network Filesystem (NFS) mount at the client side.
            For  each  NFS-mounted  filesystem,  a line is shown that contains the mounted server
            directory, the name of the server (`srv'), the total number of bytes physically  read
            from  the  server  (`read')  and  the total number of bytes physically written to the
            server (`write').  Data transfer is subdivided in the number of bytes read via normal
            read()  system  calls (`nread'), the number of bytes written via normal read() system
            calls (`nwrit'), the number of bytes read via direct I/O  (`dread'),  the  number  of
            bytes  written  via  direct I/O (`dwrit'), the number of bytes read via memory mapped
            I/O pages (`mread'), and the number of bytes written  via  memory  mapped  I/O  pages
            (`mwrit').

       NFC  Network Filesystem (NFS) client side counters.
            This  line  contains  the  number of RPC calls issues by local processes (`rpc'), the
            number of read RPC calls (`read`) and write RPC calls (`rpwrite') issued to  the  NFS
            server,  the  number  of  RPC calls being retransmitted (`retxmit') and the number of
            authorization refreshes (`autref').

       NFS  Network Filesystem (NFS) server side counters.
            This line contains the number of RPC calls received from  NFS  clients  (`rpc'),  the
            number  of  read RPC calls received (`cread`), the number of write RPC calls received
            (`cwrit'), the number of  Megabytes/second  returned  to  read  requests  by  clients
            (`MBcr/s`),  the  number  of  Megabytes/second  passed  in  write requests by clients
            (`MBcw/s`), the number of network requests handled via TCP (`nettcp'), the number  of
            network  requests  handled  via  UDP  (`netudp'),  the  number  of  reply  cache hits
            (`rchits'), the number of reply cache misses (`rcmiss') and the  number  of  uncached
            requests  (`rcnoca').   Furthermore  some  error  counters  indicating  the number of
            requests with a bad format (`badfmt')  or  a  bad  authorization  (`badaut'),  and  a
            counter indicating the number of bad clients (`badcln').

       NET  Network utilization (TCP/IP).
            One line is shown for activity of the transport layer (TCP and UDP), one line for the
            IP layer and one line per active interface.
            For the transport layer, counters are shown concerning the  number  of  received  TCP
            segments  including  those  received in error (`tcpi'), the number of transmitted TCP
            segments excluding those containing only retransmitted octets (`tcpo'), the number of
            UDP  datagrams  received  (`udpi'), the number of UDP datagrams transmitted (`udpo'),
            the number of active TCP opens (`tcpao'), the number of passive TCP opens  (`tcppo'),
            the  number  of  TCP output retransmissions (`tcprs'), the number of TCP input errors
            (`tcpie'), the number of TCP output resets (`tcpor'), the  number  of  UDP  no  ports
            (`udpnp'), and the number of UDP input errors (`udpie').
            If  the  screen-width does not allow all of these counters, only a relevant subset is
            shown.
            These counters are related to IPv4 and IPv6 combined.

            For the IP layer, counters are shown concerning the number of IP  datagrams  received
            from  interfaces,  including  those  received  in  error  (`ipi'),  the  number of IP
            datagrams that local higher-layer protocols offered  for  transmission  (`ipo'),  the
            number  of  received IP datagrams which were forwarded to other interfaces (`ipfrw'),
            the number of IP datagrams which  were  delivered  to  local  higher-layer  protocols
            (`deliv'),  the  number  of  received  ICMP  datagrams  (`icmpi'),  and the number of
            transmitted ICMP datagrams (`icmpo').
            If the screen-width does not allow all of these counters, only a relevant  subset  is
            shown.
            These counters are related to IPv4 and IPv6 combined.

            For  every  active  network  interface  one  line  is  shown, sorted on the interface
            activity.  Such line shows the name of the interface and its busy percentage  in  the
            first  column.   The  busy  percentage for half duplex is determined by comparing the
            interface speed with the number of bits transmitted and received per second; for full
            duplex  the interface speed is compared with the highest of either the transmitted or
            the received bits.  When the interface speed can not  be  determined  (e.g.  for  the
            loopback interface), `---' is shown instead of the percentage.
            Furthermore  the  number  of  received  packets  (`pcki'),  the number of transmitted
            packets (`pcko'), the line speed of the interface (`sp'),  the  effective  amount  of
            bits  received per second (`si'), the effective amount of bits transmitted per second
            (`so'), the number of collisions (`coll'), the number of received  multicast  packets
            (`mlti'),  the  number  of  errors  while  receiving a packet (`erri'), the number of
            errors while transmitting a packet (`erro'), the number of received  packets  dropped
            (`drpi'), and the number of transmitted packets dropped (`drpo').
            If  the  screen-width does not allow all of these counters, only a relevant subset is
            shown.
            The number of lines showing the network interfaces can be limited.

       IFB  Infiniband utilization.
            For every active Infiniband port one line is shown, sorted on  activity.   Such  line
            shows  the  name  of  the port and its busy percentage in the first column.  The busy
            percentage is determined by taking the highest  of  either  the  transmitted  or  the
            received  bits during the interval, multiplying that value by the number of lanes and
            comparing it against the maximum port speed.
            Furthermore the number of received packets divided by the number of  lanes  (`pcki'),
            the  number  of  transmitted  packets  divided  by  the number of lanes (`pcko'), the
            maximum line speed (`sp'), the effective amount of bits received per  second  (`si'),
            the  effective  amount of bits transmitted per second (`so'), and the number of lanes
            (`lanes').
            If the screen-width does not allow all of these counters, only a relevant  subset  is
            shown.
            The number of lines showing the Infiniband ports can be limited.

OUTPUT DESCRIPTION - PROCESS LEVEL

       Following  the  system  level information, the processes are shown from which the resource
       utilization has changed during the last interval. These processes might have used cpu time
       or issued disk or network requests. However a process is also shown if part of it has been
       paged out due to lack of memory (while the process itself was in sleep state).

       Per process the following fields may be shown (in alphabetical order),  depending  on  the
       current  output mode as described in the section INTERACTIVE COMMANDS and depending on the
       current width of your window:

       AVGRSZ   The average size of one read-action on disk.

       AVGWSZ   The average size of one write-action on disk.

       BANDWI   Total bandwidth for received TCP and UDP packets consumed by this process  (bits-
                per-second).   This  value can be compared with the value `si' on interface level
                (used bandwidth per interface).
                This information will only be shown when the kernel module `netatop' is loaded.

       BANDWO   Total bandwidth for sent TCP and UDP packets consumed by this process  (bits-per-
                second).  This value can be compared with the value `so' on interface level (used
                bandwidth per interface).
                This information will only be shown when the kernel module `netatop' is loaded.

       CID      Container ID (Docker) of 12 hexadecimal digits, referring  to  the  container  in
                which  the process/thread is running.  If a process has been started and finished
                during the last interval, a `?' is shown because the container ID is not part  of
                the standard process accounting record.

       CMD      The  name  of  the  process.   This name can be surrounded by "less/greater than"
                signs (`<name>') which means that  the  process  has  finished  during  the  last
                interval.
                Behind the abbreviation `CMD' in the header line, the current page number and the
                total number of pages of the process/thread list are shown.

       COMMAND-LINE
                The full command line of the process (including arguments). If the length of  the
                command  line exceeds the length of the screen line, the arrow keys -> and <- can
                be used for horizontal scroll.
                Behind the verb `COMMAND-LINE' in the header line, the current  page  number  and
                the total number of pages of the process/thread list are shown.

       CPU      The  occupation  percentage of this process related to the available capacity for
                this resource on system level.

       CPUNR    The identification of the CPU the (main) thread is running  on  or  has  recently
                been running on.

       CTID     Container  ID  (OpenVZ).   If  a process has been started and finished during the
                last interval, a `?' is shown because  the  container  ID  is  not  part  of  the
                standard process accounting record.

       DSK      The  occupation  percentage  of  this  process  related to the total load that is
                produced by all processes (i.e. total disk accesses by all processes  during  the
                last interval).
                This  information is shown when per process "storage accounting" is active in the
                kernel.

       EGID     Effective group-id under which this process executes.

       ENDATE   Date that the process has been finished. If the process is  still  running,  this
                field shows `active'.

       ENTIME   Time  that  the  process has been finished. If the process is still running, this
                field shows `active'.

       ENVID    Virtual environment identified (OpenVZ only).

       EUID     Effective user-id under which this process executes.

       EXC      The exit code of a terminated process (second position of column `ST'  is  E)  or
                the fatal signal number (second position of column `ST' is S or C).

       FSGID    Filesystem group-id under which this process executes.

       FSUID    Filesystem user-id under which this process executes.

       GPU      When  the  atopgpud  daemon does not run with root privileges, the GPU percentage
                reflects the GPU memory occupation percentage (memory of all GPUs is 100%).
                When the atopgpud daemon runs with root privileges, the GPU  percentage  reflects
                the GPU busy percentage.

       GPUBUSY  Busy percentage on all GPUs (one GPU is 100%).
                When  the  atopgpud  daemon  does not run with root privileges, this value is not
                available.

       GPUNUMS  Comma-separated list of GPUs used by the process during the  interval.  When  the
                comma-separated  list  exceeds  the  width  of the column, a hexadecimal value is
                shown.

       LOCKSZ   The virtual amount of memory being locked (i.e. non-swappable)  by  this  process
                (or user).

       MAJFLT   The  number  of  page  faults  issued  by  this  process that have been solved by
                creating/loading the requested memory page.

       MEM      The occupation percentage of this process related to the available  capacity  for
                this resource on system level.

       MEMAVG   Average memory occupation during the interval on all used GPUs.

       MEMBUSY  Busy  percentage  of  memory on all GPUs (one GPU is 100%), i.e.  the time needed
                for read and write accesses on memory.
                When the atopgpud daemon does not run with root privileges,  this  value  is  not
                available.

       MEMNOW   Memory occupation at the moment of the sample on all used GPUs.

       MINFLT   The  number  of  page  faults  issued  by  this  process that have been solved by
                reclaiming the requested memory page from the free list of pages.

       NET      The occupation percentage of this process related  to  the  total  load  that  is
                produced  by  all  processes  (i.e.  consumed  network bandwidth of all processes
                during the last interval).
                This information will only be shown when kernel module `netatop' is loaded.

       NICE     The more or less static priority that can be given to a process on a  scale  from
                -20 (high priority) to +19 (low priority).

       NPROCS   The  number  of  active  and  terminated  processes  accumulated for this user or
                program.

       PID      Process-id.  If a process has been started and finished during the last interval,
                a  `?'  is  shown  because  the  process-id  is  not part of the standard process
                accounting record.

       POLI     The policies 'norm' (normal, which is SCHED_OTHER),  'btch'  (batch)  and  'idle'
                refer to timesharing processes.  The policies 'fifo' (SCHED_FIFO) and 'rr' (round
                robin, which is SCHED_RR) refer to realtime processes.

       PPID     Parent process-id.  If a process has been started and finished  during  the  last
                interval,  value  0  is  shown  because  the parent process-id is not part of the
                standard process accounting record.

       PRI      The process' priority ranges from 0 (highest priority) to 139 (lowest  priority).
                Priority  0  to 99 are used for realtime processes (fixed priority independent of
                their behavior) and priority 100  to  139  for  timesharing  processes  (variable
                priority depending on their recent CPU consumption and the nice value).

       PSIZE    The proportional memory size of this process (or user).
                Every process shares resident memory with other processes. E.g. when a particular
                program is started several times, the code pages (text) are only loaded  once  in
                memory  and  shared  by  all  incarnations.  Also the code of shared libraries is
                shared by all processes using that shared library, as well as shared  memory  and
                memory-mapped files.  For the PSIZE calculation of a process, the resident memory
                of a process that is shared with other processes is  divided  by  the  number  of
                sharers.   This means, that every process is accounted for a proportional part of
                that memory. Accumulating the PSIZE values of all processes in the system gives a
                reliable impression of the total resident memory consumed by all processes.
                Since  gathering  of  all values that are needed to calculate the PSIZE is a very
                time-consuming task, the 'R' key (or '-R' flag) should be active. Gathering these
                values  also  requires  superuser  privileges  (otherwise  '?K'  is  shown in the
                output).
                If a process has finished during the last interval, no value is shown  since  the
                proportional memory size is not part of the standard process accounting record.

       RDDSK    When the kernel maintains standard io statistics (>= 2.6.20):
                The  read data transfer issued physically on disk (so reading from the disk cache
                is not accounted for).
                Unfortunately, the kernel aggregates the data tranfer of a process  to  the  data
                transfer  of  its parent process when terminating, so you might see transfers for
                (parent) processes like cron, bash or init, that are not really issued by them.

       RDELAY   Runqueue delay, i.e. time spent waiting on a runqueue.

       RGID     The real group-id under which the process executes.

       RGROW    The amount of resident  memory  that  the  process  has  grown  during  the  last
                interval. A resident growth can be caused by touching memory pages which were not
                physically created/loaded before (load-on-demand).  Note that a  resident  growth
                can  also  be  negative e.g. when part of the process is paged out due to lack of
                memory or when the process frees dynamically allocated  memory.   For  a  process
                which  started  during  the last interval, the resident growth reflects the total
                resident size of the process at that moment.
                If a process has finished during the last  interval,  no  value  is  shown  since
                resident memory occupation is not part of the standard process accounting record.

       RNET     The  number  of  TCP- and UDP packets received by this process.  This information
                will only be shown when kernel module `netatop' is installed.
                If a process has finished during the last  interval,  no  value  is  shown  since
                network counters are not part of the standard process accounting record.

       RSIZE    The  total resident memory usage consumed by this process (or user).  Notice that
                the RSIZE of a process includes all resident memory used by that process, even if
                certain memory parts are shared with other processes (see also the explanation of
                PSIZE).
                If a process has finished during the last  interval,  no  value  is  shown  since
                resident memory occupation is not part of the standard process accounting record.

       RTPR     Realtime priority according the POSIX standard.  Value can be 0 for a timesharing
                process (policy 'norm', 'btch' or 'idle') or  ranges  from  1  (lowest)  till  99
                (highest) for a realtime process (policy 'rr' or 'fifo').

       RUID     The real user-id under which the process executes.

       S        The  current state of the (main) thread: `R' for running (currently processing or
                in the runqueue), `S' for sleeping interruptible (wait for an  event  to  occur),
                `D'  for  sleeping  non-interruptible, `Z' for zombie (waiting to be synchronized
                with its parent  process),  `T'  for  stopped  (suspended  or  traced),  `W'  for
                swapping,  and  `E'  (exit)  for  processes  which  have finished during the last
                interval.

       SGID     The saved group-id of the process.

       SNET     The number of TCP and UDP packets transmitted by this process.  This  information
                will only be shown when the kernel module `netatop' is loaded.

       ST       The status of a process.
                The  first  position  indicates  if  the process has been started during the last
                interval (the value N means 'new process').

                The second position indicates if the process has been finished  during  the  last
                interval.
                The  value  E  means  'exit'  on  the  process'  own initiative; the exit code is
                displayed in the column `EXC'.
                The value S means that the process has been terminated unvoluntarily by a signal;
                the signal number is displayed in the in the column `EXC'.
                The value C means that the process has been terminated unvoluntarily by a signal,
                producing a core dump in its current directory; the signal number is displayed in
                the column `EXC'.

       STDATE   The start date of the process.

       STTIME   The start time of the process.

       SUID     The saved user-id of the process.

       SWAPSZ   The swap space consumed by this process (or user).

       SYSCPU   CPU time consumption of this process in system mode (kernel mode), usually due to
                system call handling.

       TCPRASZ  The average size of a received TCP buffer in bytes.  This information  will  only
                be shown when the kernel module `netatop' is loaded.

       TCPRCV   The  number of TCP packets received for this process.  This information will only
                be shown when the kernel module `netatop' is loaded.

       TCPSASZ  The average size of a transmitted TCP buffer in  bytes.   This  information  will
                only be shown when the kernel module `netatop' is loaded.

       TCPSND   The  number  of  TCP packets transmitted for this process.  This information will
                only be shown when the kernel module `netatop' is loaded.

       THR      Total number of threads within this process.  All related threads  are  contained
                in a thread group, represented by atop as one line or as a separate line when the
                'y' key (or -y flag) is active.

                On Linux 2.4 systems it is hardly  possible  to  determine  which  threads  (i.e.
                processes)  are related to the same thread group.  Every thread is represented by
                atop as a separate line.

       TID      Thread-id.  All threads within a process  run  with  the  same  PID  but  with  a
                different  TID.  This  value  is  shown  for individual threads in multi-threaded
                processes (when using the key 'y').

       TRUN     Number of threads within this process that are in the state 'running' (R).

       TSLPI    Number of threads within this  process  that  are  in  the  state  'interruptible
                sleeping' (S).

       TSLPU    Number  of  threads  within  this  process that are in the state 'uninterruptible
                sleeping' (D).

       UDPRASZ  The average size of a received UDP packet in bytes.  This information  will  only
                be shown when the kernel module `netatop' is loaded.

       UDPRCV   The  number  of UDP packets received by this process.  This information will only
                be shown when the kernel module `netatop' is loaded.

       UDPSASZ  The average size of a transmitted UDP packets in bytes.   This  information  will
                only be shown when the kernel module `netatop' is loaded.

       UDPSND   The  number  of  UDP  packets transmitted by this process.  This information will
                only be shown when the kernel module `netatop' is loaded.

       USRCPU   CPU time consumption of this process in user mode,  due  to  processing  the  own
                program text.

       VDATA    The  virtual memory size of the private data used by this process (including heap
                and shared library data).

       VGROW    The amount of virtual memory that the process has grown during the last interval.
                A  virtual growth can be caused by e.g. issueing a malloc() or attaching a shared
                memory segment. Note that a virtual growth can also be negative by e.g.  issueing
                a  free()  or  detaching  a  shared  memory segment.  For a process which started
                during the last interval, the virtual growth reflects the total virtual  size  of
                the process at that moment.
                If  a  process  has  finished  during  the last interval, no value is shown since
                virtual memory occupation is not part of the standard process accounting record.

       VPID     Virtual process-id (within an OpenVZ container).  If a process has  been  started
                and  finished  during  the  last  interval,  a  `?'  is shown because the virtual
                process-id is not part of the standard process accounting record.

       VSIZE    The total virtual memory usage consumed by this process (or user).
                If a process has finished during the last  interval,  no  value  is  shown  since
                virtual memory occupation is not part of the standard process accounting record.

       VSLIBS   The virtual memory size of the (shared) text of all shared libraries used by this
                process.

       VSTACK   The virtual memory size of the (private) stack used by this process

       VSTEXT   The virtual memory size of the (shared) text of the executable program.

       WCHAN    Wait channel of thread in sleep state, i.e. the name of the  kernel  function  in
                which the thread has been put asleep.
                Since  determining  the  name string of the kernel function is a relatively time-
                consuming task, the 'W' key (or '-W' flag) should be active.

       WRDSK    When the kernel maintains standard io statistics (>= 2.6.20):
                The write data transfer issued physically on disk (so writing to the  disk  cache
                is  not  accounted  for).  This counter is maintained for the application process
                that writes its data  to  the  cache  (assuming  that  this  data  is  physically
                transferred  to  disk  later on). Notice that disk I/O needed for swapping is not
                taken into account.
                Unfortunately, the kernel aggregates the data tranfer of a process  to  the  data
                transfer  of  its parent process when terminating, so you might see transfers for
                (parent) processes like cron, bash or init, that are not really issued by them.

       WCANCL   When the kernel maintains standard io statistics (>= 2.6.20):
                The write data transfer previously accounted for this process or another  process
                that  has  been  cancelled.  Suppose that a process writes new data to a file and
                that data is removed again before the cache buffers have been  flushed  to  disk.
                Then the original process shows the written data as WRDSK, while the process that
                removes/truncates the file shows the unflushed removed data as WCANCL.

PARSEABLE OUTPUT

       With the flag -P followed by a list of one or  more  labels  (comma-separated),  parseable
       output  is  produced  for  each sample.  The labels that can be specified for system-level
       statistics correspond to the labels (first verb of each line) that can  be  found  in  the
       interactive  output: "CPU", "cpu", "CPL", "GPU", "MEM", "SWP", "PAG", "PSI", "LVM", "MDD",
       "DSK", "NFM", "NFC", "NFS", "NET" and "IFB".
       For process-level statistics special labels are introduced: "PRG" (general), "PRC"  (cpu),
       "PRE"  (GPU),  "PRM"  (memory),  "PRD"  (disk, only if "storage accounting" is active) and
       "PRN" (network, only if the kernel module 'netatop' has been installed).
       With the label "ALL", all system and process level statistics are shown.

       For every interval all requested lines  are  shown  whereafter  atop  shows  a  line  just
       containing  the  label  "SEP"  as  a  separator  before  the lines for the next sample are
       generated.
       When a sample contains the values since boot, atop shows a line just containing the  label
       "RESET" before the lines for this sample are generated.

       The  first  part of each output-line consists of the following six fields: label (the name
       of the label), host (the name of this machine), epoch (the time of this interval as number
       of  seconds since 1-1-1970), date (date of this interval in format YYYY/MM/DD), time (time
       of this interval in format HH:MM:SS), and interval (number of  seconds  elapsed  for  this
       interval).

       The subsequent fields of each output-line depend on the label:

       CPU      Subsequent  fields:  total  number  of  clock-ticks  per second for this machine,
                number of processors, consumption for all  CPUs  in  system  mode  (clock-ticks),
                consumption  for all CPUs in user mode (clock-ticks), consumption for all CPUs in
                user mode for niced processes (clock-ticks), consumption for  all  CPUs  in  idle
                mode  (clock-ticks),  consumption  for  all  CPUs  in  wait  mode  (clock-ticks),
                consumption for all CPUs in irq mode (clock-ticks), consumption for all  CPUs  in
                softirq mode (clock-ticks), consumption for all CPUs in steal mode (clock-ticks),
                consumption for all CPUs in  guest  mode  (clock-ticks)  overlapping  user  mode,
                frequency of all CPUs, frequency percentage of all CPUs, instructions executed by
                all CPUs and cycles for all CPUs.

       cpu      Subsequent fields: total number of  clock-ticks  per  second  for  this  machine,
                processor-number,   consumption  for  this  CPU  in  system  mode  (clock-ticks),
                consumption for this CPU in user mode (clock-ticks), consumption for this CPU  in
                user  mode  for  niced  processes (clock-ticks), consumption for this CPU in idle
                mode  (clock-ticks),  consumption  for  this  CPU  in  wait  mode  (clock-ticks),
                consumption  for  this CPU in irq mode (clock-ticks), consumption for this CPU in
                softirq mode (clock-ticks), consumption for this CPU in steal mode (clock-ticks),
                consumption  for  this  CPU  in  guest  mode (clock-ticks) overlapping user mode,
                frequency of this CPU, frequency percentage of this CPU, instructions executed by
                this CPU and cycles for this CPU.

       CPL      Subsequent  fields:  number  of  processors,  load  average for last minute, load
                average for last five minutes, load average for last fifteen minutes,  number  of
                context-switches, and number of device interrupts.

       GPU      Subsequent  fields:  GPU  number,  bus-id  string,  type  of GPU string, GPU busy
                percentage during last second (-1  if  not  available),  memory  busy  percentage
                during  last  second  (-1 if not available), total memory size (KiB), used memory
                (KiB) at this moment, number of samples taken  during  interval,  cumulative  GPU
                busy  percentage  during the interval (to be divided by the number of samples for
                the average busy  percentage,  -1  if  not  available),  cumulative  memory  busy
                percentage  during  the  interval (to be divided by the number of samples for the
                average busy percentage, -1 if not available), and cumulative  memory  occupation
                during  the  interval  (to  be  divided  by the number of samples for the average
                occupation).

       MEM      Subsequent fields: page size for this machine (in bytes), size of physical memory
                (pages),  size of free memory (pages), size of page cache (pages), size of buffer
                cache (pages), size of slab (pages), dirty pages in  cache  (pages),  reclaimable
                part of slab (pages), total size of vmware's balloon pages (pages), total size of
                shared memory (pages), size of resident shared memory (pages),  size  of  swapped
                shared  memory (pages), huge page size (in bytes), total size of huge pages (huge
                pages), size of free huge  pages  (huge  pages),  and  size  of  ARC  (cache)  of
                ZFSonlinux (pages).

       SWP      Subsequent  fields:  page size for this machine (in bytes), size of swap (pages),
                size of free swap (pages), size of swap cache (pages), size  of  committed  space
                (pages), and limit for committed space (pages).

       PAG      Subsequent  fields:  page size for this machine (in bytes), number of page scans,
                number of allocstalls, 0 (future use), number of swapins, and number of swapouts.

       PSI      Subsequent fields: PSI statistics present on this  system  (n  or  y),  CPU  some
                avg10,  CPU some avg60, CPU some avg300, CPU some accumulated microseconds during
                interval, memory some avg10, memory some avg60, memory some avg300,  memory  some
                accumulated  microseconds  during interval, memory full avg10, memory full avg60,
                memory full avg300, memory full accumulated  microseconds  during  interval,  I/O
                some  avg10,  I/O  some avg60, I/O some avg300, I/O some accumulated microseconds
                during interval, I/O full avg10, I/O full avg60, I/O full avg300,  and  I/O  full
                accumulated microseconds during interval.

       LVM/MDD/DSK
                For every logical volume/multiple device/hard disk one line is shown.
                Subsequent  fields:  name,  number of milliseconds spent for I/O, number of reads
                issued, number of sectors transferred for reads, number  of  writes  issued,  and
                number of sectors transferred for write.

       NFM      Subsequent  fields:  mounted  NFS  filesystem,  total number of bytes read, total
                number of bytes written, number of bytes read by normal system calls,  number  of
                bytes  written by normal system calls, number of bytes read by direct I/O, number
                of bytes written by direct I/O, number of pages read by  memory-mapped  I/O,  and
                number of pages written by memory-mapped I/O.

       NFC      Subsequent  fields:  number of transmitted RPCs, number of transmitted read RPCs,
                number of transmitted write RPCs, number of RPC retransmissions,  and  number  of
                authorization refreshes.

       NFS      Subsequent  fields:  number of handled RPCs, number of received read RPCs, number
                of received write RPCs, number of bytes read by clients, number of bytes  written
                by   clients,   number  of  RPCs  with  bad  format,  number  of  RPCs  with  bad
                authorization, number of RPCs from bad client, total number  of  handled  network
                requests,  number  of handled network requests via TCP, number of handled network
                requests via UDP, number of handled TCP connections,  number  of  hits  on  reply
                cache, number of misses on reply cache, and number of uncached requests.

       NET      First, one line is produced for the upper layers of the TCP/IP stack.
                Subsequent fields: the verb "upper", number of packets received by TCP, number of
                packets transmitted by TCP, number of packets received by UDP, number of  packets
                transmitted  by  UDP,  number  of  packets  received  by  IP,  number  of packets
                transmitted by IP, number of packets delivered to higher layers by IP, number  of
                packets  forwarded  by  IP, number of input errors (UDP), number of noport errors
                (UDP), number of active opens (TCP), number of passive  opens  (TCP),  number  of
                passive  opens  (TCP),  number  of  established connections at this moment (TCP),
                number of retransmitted segments (TCP), number of input errors (TCP), and  number
                of output resets (TCP).

                Next, one line is shown for every interface.
                Subsequent  fields:  name  of  the  interface,  number of packets received by the
                interface,  number  of  bytes  received  by  the  interface,  number  of  packets
                transmitted  by  the  interface,  number  of  bytes transmitted by the interface,
                interface speed, and duplex mode (0=half, 1=full).

       IFB      Subsequent fields: name of the  InfiniBand  interface,  port  number,  number  of
                lanes,   maximum   rate  (Mbps),  number  of  bytes  received,  number  of  bytes
                transmitted, number of packets received, and number of packets transmitted.

       PRG      For every process one line is shown.
                Subsequent fields: PID (unique ID of task), name (between brackets), state,  real
                uid,  real  gid,  TGID  (group  number of related tasks/threads), total number of
                threads, exit code (in case of fatal signal: signal number  +  256),  start  time
                (epoch),  full  command line (between brackets), PPID, number of threads in state
                'running' (R), number of threads in state 'interruptible sleeping' (S), number of
                threads  in  state  'uninterruptible sleeping' (D), effective uid, effective gid,
                saved uid, saved gid, filesystem  uid,  filesystem  gid,  elapsed  time  (hertz),
                is_process  (y/n), OpenVZ  virtual pid (VPID), OpenVZ container id (CTID), Docker
                container id (CID), and indication if the  task  is  newly  started  during  this
                interval ('N').

       PRC      For every process one line is shown.
                Subsequent  fields:  PID,  name (between brackets), state, total number of clock-
                ticks per second for this machine, CPU-consumption  in  user  mode  (clockticks),
                CPU-consumption  in  system  mode  (clockticks),  nice  value, priority, realtime
                priority, scheduling policy, current CPU, sleep average, TGID  (group  number  of
                related  tasks/threads), is_process (y/n), runqueue delay in nanoseconds for this
                thread or for all threads (in case of process), and wait channel of  this  thread
                (between brackets).

       PRE      For every process one line is shown.
                Subsequent  fields: PID, name (between brackets), process state, GPU state (A for
                active, E for exited, N for no GPU user), number of GPUs used  by  this  process,
                bitlist  reflecting  used  GPUs, GPU busy percentage during interval, memory busy
                percentage during interval, memory occupation (KiB)  at  this  moment  cumulative
                memory  occupation  (KiB)  during  interval,  and  number of samples taken during
                interval.

       PRM      For every process one line is shown.
                Subsequent fields: PID, name  (between  brackets),  state,  page  size  for  this
                machine  (in bytes), virtual memory size (Kbytes), resident memory size (Kbytes),
                shared text memory size (Kbytes), virtual memory growth (Kbytes), resident memory
                growth  (Kbytes),  number  of  minor  page  faults,  number of major page faults,
                virtual library exec size (Kbytes), virtual data  size  (Kbytes),  virtual  stack
                size   (Kbytes),  swap  space  used  (Kbytes),  TGID  (group  number  of  related
                tasks/threads), is_process (y/n), proportional set size (Kbytes) if in 'R' option
                is specified and virtually locked memory space (Kbytes).

       PRD      For every process one line is shown.
                Subsequent  fields:  PID,  name (between brackets), state, obsoleted kernel patch
                installed ('n'), standard io statistics used ('y' or 'n'),  number  of  reads  on
                disk,  cumulative  number  of  sectors read, number of writes on disk, cumulative
                number of sectors written, cancelled  number  of  written  sectors,  TGID  (group
                number of related tasks/threads), obsoleted value ('n'), and is_process (y/n).
                If  the  standard  I/O statistics (>= 2.6.20) are not used, the disk I/O counters
                per process are not relevant.  The counters 'number of reads on disk' and 'number
                of writes on disk' are obsoleted anyhow.

       PRN      For every process one line is shown.
                Subsequent  fields:  PID, name (between brackets), state, kernel module 'netatop'
                loaded ('y' or 'n'), number of TCP-packets transmitted, cumulative size  of  TCP-
                packets  transmitted,  number  of  TCP-packets  received, cumulative size of TCP-
                packets received, number of UDP-packets  transmitted,  cumulative  size  of  UDP-
                packets  transmitted,  number  of  UDP-packets  received, cumulative size of UDP-
                packets transmitted, number of raw  packets  transmitted  (obsolete,  always  0),
                number  of  raw  packets  received  (obsolete,  always  0), TGID (group number of
                related tasks/threads) and is_process (y/n).
                If the kernel module is not active, the network I/O counters per process are  not
                relevant.

SIGNALS

       By  sending  the  SIGUSR1  signal to atop a new sample will be forced, even if the current
       timer interval has not exceeded yet. The behavior is similar to pressing the `t` key in an
       interactive session.

       By  sending the SIGUSR2 signal to atop a final sample will be forced after which atop will
       terminate.

EXAMPLES

       To monitor the current system load interactively with an interval of 5 seconds:

         atop 5

       To monitor the system load and write it to a file (in plain ASCII) with an interval of one
       minute during half an hour with active processes sorted on memory consumption:

         atop -M 60 30 > /log/atop.mem

       Store  information  about  the  system and process activity in binary compressed form to a
       file with an interval of ten minutes during an hour:

         atop -w /tmp/atop.raw 600 6

       View the contents of this file interactively:

         atop -r /tmp/atop.raw

       View the processor and disk utilization of this file in parseable format:

         atop -PCPU,DSK -r /tmp/atop.raw

       View the contents of today's standard logfile interactively:

         atop -r

       View the contents of the standard logfile of the day before yesterday interactively:

         atop -r yy

       View the contents of  the  standard  logfile  of  2014,  June  7  from  02:00  PM  onwards
       interactively:

         atop -r 20140607 -b 1400

       Concatenate  all  raw log files of January 2020 and generate parsable output about the CPU
       utilization:

         atopcat /var/log/atop/atop_202001?? | atop -r - -PCPU

FILES

       /run/pacct_shadow.d/
            Directory containing the process accounting shadow files that are used by  atop  when
            the atopacctd daemon is active.

       /var/cache/atop.d/atop.acct
            File in which the kernel writes the accounting records when atop itself has activated
            the process accounting mechanism.

       /etc/atoprc
            Configuration file containing system-wide default values.  See related man-page.

       ~/.atoprc
            Configuration file containing personal default values.  See related man-page.

       /etc/default/atop
            Configuration file to overrule the settings of atop that runs in  the  background  to
            create  the daily logfile.  This file is created when atop is installed.  The default
            settings are:

       LOGOPTS=""
               LOGINTERVAL=600
               LOGGENERATIONS=28

       /var/log/atop/atop_YYYYMMDD
            Raw file, where YYYYMMDD are digits representing the current date.  This name is used
            by atop running in the background as default name for the output file, and by atop as
            default name for the input file when using the -r flag.
            All binary system and process level data in this file has been stored  in  compressed
            format.

       /run/netatop.log
            File  that  contains the netpertask structs containing the network counters of exited
            processes. These structs are written by the netatopd daemon and read  by  atop  after
            reading the standard process accounting records.

SEE ALSO

       atopsar(1),  atopconvert(1), atopcat(1), atoprc(5), atopacctd(8), netatop(4), netatopd(8),
       atopgpud(8), logrotate(8)
       https://www.atoptool.nl

AUTHOR

       Gerlof Langeveld (gerlof.langeveld@atoptool.nl)
       JC van Winkel