NAME

       biotop - Block device (disk) I/O by process top.

SYNOPSIS

       biotop [-h] [-C] [-r MAXROWS] [interval] [count]

DESCRIPTION

       This is top for disks.

       This  traces  block device I/O (disk I/O), and prints a per-process summary every interval
       (by default, 1 second). The summary is sorted on the  top  disk  consumers  by  throughput
       (Kbytes). The PID and process name shown are measured from when the I/O was first created,
       which usually identifies the responsible process.

       For efficiency, this uses in-kernel eBPF maps to cache process details (PID and  comm)  by
       I/O  request,  as  well as a starting timestamp for calculating I/O latency, and the final
       summary.

       This works by tracing various kernel blk_*() functions using  dynamic  tracing,  and  will
       need updating to match any changes to these functions.

       Since this uses BPF, only the root user can use this tool.

REQUIREMENTS

       CONFIG_BPF and bcc.

OPTIONS

       -C     Don't clear the screen.

       -r MAXROWS
              Maximum number of rows to print. Default is 20.

       -p PID Trace this PID only.

       interval
              Interval between updates, seconds.

       count  Number of interval summaries.

EXAMPLES

       Summarize block device I/O by process, 1 second screen refresh:
              # biotop

       Don't clear the screen:
              # biotop -C

       5 second summaries, 10 times only:
              # biotop 5 10

FIELDS

       loadavg:
              The contents of /proc/loadavg

       PID    Cached  process ID, if present. This usually (but isn't guaranteed) to identify the
              responsible process for the I/O.

       COMM   Cached process name, if present. This usually (but isn't  guaranteed)  to  identify
              the responsible process for the I/O.

       D      Direction: R == read, W == write. This is a simplification.

       MAJ    Major device number.

       MIN    Minor device number.

       DISK   Disk device name.

       I/O    Number of I/O during the interval.

       Kbytes Total Kbytes for these I/O, during the interval.

       AVGms  Average time for the I/O (latency) from the issue to the device, to its completion,
              in milliseconds.

OVERHEAD

       Since block device I/O usually has a relatively low frequency (< 10,000/s),  the  overhead
       for this tool is expected to be low or negligible. For high IOPS storage systems, test and
       quantify before use.

SOURCE

       This is from bcc.

              https://github.com/iovisor/bcc

       Also look in the bcc distribution for a companion _examples.txt  file  containing  example
       usage, output, and commentary for this tool.

OS

       Linux

STABILITY

       Unstable - in development.

AUTHOR

       Brendan Gregg

INSPIRATION

       top(1) by William LeFebvre

SEE ALSO

       biosnoop(8), biolatency(8), iostat(1)