xenial (1) perf-report.1.gz

Provided by: linux-gke-tools-common_4.4.0-1013.13_all bug

NAME

       perf-report - Read perf.data (created by perf record) and display the profile

SYNOPSIS

       perf report [-i <file> | --input=file]

DESCRIPTION

       This command displays the performance counter profile information recorded via perf record.

OPTIONS

       -i, --input=
           Input file name. (default: perf.data unless stdin is a fifo)

       -v, --verbose
           Be more verbose. (show symbol address, etc)

       -n, --show-nr-samples
           Show the number of samples for each symbol

       --show-cpu-utilization
           Show sample percentage for different cpu modes.

       -T, --threads
           Show per-thread event counters. The input data file should be recorded with -s option.

       -c, --comms=
           Only consider symbols in these comms. CSV that understands file://filename entries. This option will
           affect the percentage of the overhead column. See --percentage for more info.

       --pid=
           Only show events for given process ID (comma separated list).

       --tid=
           Only show events for given thread ID (comma separated list).

       -d, --dsos=
           Only consider symbols in these dsos. CSV that understands file://filename entries. This option will
           affect the percentage of the overhead column. See --percentage for more info.

       -S, --symbols=
           Only consider these symbols. CSV that understands file://filename entries. This option will affect
           the percentage of the overhead column. See --percentage for more info.

       --symbol-filter=
           Only show symbols that match (partially) with this filter.

       -U, --hide-unresolved
           Only display entries resolved to a symbol.

       -s, --sort=
           Sort histogram entries by given key(s) - multiple keys can be specified in CSV format. Following sort
           keys are available: pid, comm, dso, symbol, parent, cpu, socket, srcline, weight, local_weight.

               Each key has following meaning:

           •   comm: command (name) of the task which can be read via /proc/<pid>/comm

           •   pid: command and tid of the task

           •   dso: name of library or module executed at the time of sample

           •   symbol: name of function executed at the time of sample

           •   parent: name of function matched to the parent regex filter. Unmatched entries are displayed as
               "[other]".

           •   cpu: cpu number the task ran at the time of sample

           •   socket: processor socket number the task ran at the time of sample

           •   srcline: filename and line number executed at the time of sample. The DWARF debugging info must
               be provided.

           •   srcfile: file name of the source file of the same. Requires dwarf information.

           •   weight: Event specific weight, e.g. memory latency or transaction abort cost. This is the global
               weight.

           •   local_weight: Local weight version of the weight above.

           •   transaction: Transaction abort flags.

           •   overhead: Overhead percentage of sample

           •   overhead_sys: Overhead percentage of sample running in system mode

           •   overhead_us: Overhead percentage of sample running in user mode

           •   overhead_guest_sys: Overhead percentage of sample running in system mode on guest machine

           •   overhead_guest_us: Overhead percentage of sample running in user mode on guest machine

           •   sample: Number of sample

           •   period: Raw number of event count of sample

                   By default, comm, dso and symbol keys are used.
                   (i.e. --sort comm,dso,symbol)

                   If --branch-stack option is used, following sort keys are also
                   available:
                   dso_from, dso_to, symbol_from, symbol_to, mispredict.

           •   dso_from: name of library or module branched from

           •   dso_to: name of library or module branched to

           •   symbol_from: name of function branched from

           •   symbol_to: name of function branched to

           •   mispredict: "N" for predicted branch, "Y" for mispredicted branch

           •   in_tx: branch in TSX transaction

           •   abort: TSX transaction abort.

           •   cycles: Cycles in basic block

                   And default sort keys are changed to comm, dso_from, symbol_from, dso_to
                   and symbol_to, see '--branch-stack'.

       -F, --fields=
           Specify output field - multiple keys can be specified in CSV format. Following fields are available:
           overhead, overhead_sys, overhead_us, overhead_children, sample and period. Also it can contain any
           sort key(s).

               By default, every sort keys not specified in -F will be appended
               automatically.

               If --mem-mode option is used, following sort keys are also available
               (incompatible with --branch-stack):
               symbol_daddr, dso_daddr, locked, tlb, mem, snoop, dcacheline.

           •   symbol_daddr: name of data symbol being executed on at the time of sample

           •   dso_daddr: name of library or module containing the data being executed on at the time of sample

           •   locked: whether the bus was locked at the time of sample

           •   tlb: type of tlb access for the data at the time of sample

           •   mem: type of memory access for the data at the time of sample

           •   snoop: type of snoop (if any) for the data at the time of sample

           •   dcacheline: the cacheline the data address is on at the time of sample

                   And default sort keys are changed to local_weight, mem, sym, dso,
                   symbol_daddr, dso_daddr, snoop, tlb, locked, see '--mem-mode'.

       -p, --parent=<regex>
           A regex filter to identify parent. The parent is a caller of this function and searched through the
           callchain, thus it requires callchain information recorded. The pattern is in the exteneded regex
           format and defaults to "^sys_|^do_page_fault", see --sort parent.

       -x, --exclude-other
           Only display entries with parent-match.

       -w, --column-widths=<width[,width...]>
           Force each column width to the provided list, for large terminal readability. 0 means no limit
           (default behavior).

       -t, --field-separator=
           Use a special separator character and don’t pad with spaces, replacing all occurrences of this
           separator in symbol names (and other output) with a .  character, that thus it’s the only non valid
           separator.

       -D, --dump-raw-trace
           Dump raw trace in ASCII.

       -g, --call-graph=<print_type,threshold[,print_limit],order,sort_key,branch>
           Display call chains using type, min percent threshold, print limit, call order, sort key and branch.
           Note that ordering of parameters is not fixed so any parement can be given in an arbitraty order. One
           exception is the print_limit which should be preceded by threshold.

               print_type can be either:
               - flat: single column, linear exposure of call chains.
               - graph: use a graph tree, displaying absolute overhead rates. (default)
               - fractal: like graph, but displays relative rates. Each branch of
                        the tree is considered as a new profiled object.
               - none: disable call chain display.

               threshold is a percentage value which specifies a minimum percent to be
               included in the output call graph.  Default is 0.5 (%).

               print_limit is only applied when stdio interface is used.  It's to limit
               number of call graph entries in a single hist entry.  Note that it needs
               to be given after threshold (but not necessarily consecutive).
               Default is 0 (unlimited).

               order can be either:
               - callee: callee based call graph.
               - caller: inverted caller based call graph.
               Default is 'caller' when --children is used, otherwise 'callee'.

               sort_key can be:
               - function: compare on functions (default)
               - address: compare on individual code addresses

               branch can be:
               - branch: include last branch information in callgraph when available.
                         Usually more convenient to use --branch-history for this.

       --children
           Accumulate callchain of children to parent entry so that then can show up in the output. The output
           will have a new "Children" column and will be sorted on the data. It requires callchains are
           recorded. See the ‘overhead calculation’ section for more details.

       --max-stack
           Set the stack depth limit when parsing the callchain, anything beyond the specified depth will be
           ignored. This is a trade-off between information loss and faster processing especially for workloads
           that can have a very long callchain stack. Note that when using the --itrace option the synthesized
           callchain size will override this value if the synthesized callchain size is bigger.

               Default: 127

       -G, --inverted
           alias for inverted caller based call graph.

       --ignore-callees=<regex>
           Ignore callees of the function(s) matching the given regex. This has the effect of collecting the
           callers of each such function into one place in the call-graph tree.

       --pretty=<key>
           Pretty printing style. key: normal, raw

       --stdio
           Use the stdio interface.

       --tui
           Use the TUI interface, that is integrated with annotate and allows zooming into DSOs or threads,
           among other features. Use of --tui requires a tty, if one is not present, as when piping to other
           commands, the stdio interface is used.

       --gtk
           Use the GTK2 interface.

       -k, --vmlinux=<file>
           vmlinux pathname

       --kallsyms=<file>
           kallsyms pathname

       -m, --modules
           Load module symbols. WARNING: This should only be used with -k and a LIVE kernel.

       -f, --force
           Don’t complain, do it.

       --symfs=<directory>
           Look for files with symbols relative to this directory.

       -C, --cpu
           Only report samples for the list of CPUs provided. Multiple CPUs can be provided as a comma-separated
           list with no space: 0,1. Ranges of CPUs are specified with -: 0-2. Default is to report samples on
           all CPUs.

       -M, --disassembler-style=
           Set disassembler style for objdump.

       --source
           Interleave source code with assembly code. Enabled by default, disable with --no-source.

       --asm-raw
           Show raw instruction encoding of assembly instructions.

       --show-total-period
           Show a column with the sum of periods.

       -I, --show-info
           Display extended information about the perf.data file. This adds information which may be very large
           and thus may clutter the display. It currently includes: cpu and numa topology of the host system.

       -b, --branch-stack
           Use the addresses of sampled taken branches instead of the instruction address to build the
           histograms. To generate meaningful output, the perf.data file must have been obtained using perf
           record -b or perf record --branch-filter xxx where xxx is a branch filter option. perf report is able
           to auto-detect whether a perf.data file contains branch stacks and it will automatically switch to
           the branch view mode, unless --no-branch-stack is used.

       --branch-history
           Add the addresses of sampled taken branches to the callstack. This allows to examine the path the
           program took to each sample. The data collection must have used -b (or -j) and -g.

       --objdump=<path>
           Path to objdump binary.

       --group
           Show event group information together.

       --demangle
           Demangle symbol names to human readable form. It’s enabled by default, disable with --no-demangle.

       --demangle-kernel
           Demangle kernel symbol names to human readable form (for C++ kernels).

       --mem-mode
           Use the data addresses of samples in addition to instruction addresses to build the histograms. To
           generate meaningful output, the perf.data file must have been obtained using perf record -d -W and
           using a special event -e cpu/mem-loads/ or -e cpu/mem-stores/. See perf mem for simpler access.

       --percent-limit
           Do not show entries which have an overhead under that percent. (Default: 0).

       --percentage
           Determine how to display the overhead percentage of filtered entries. Filters can be applied by
           --comms, --dsos and/or --symbols options and Zoom operations on the TUI (thread, dso, etc).

               "relative" means it's relative to filtered entries only so that the
               sum of shown entries will be always 100%.  "absolute" means it retains
               the original value before and after the filter is applied.

       --header
           Show header information in the perf.data file. This includes various information like hostname, OS
           and perf version, cpu/mem info, perf command line, event list and so on. Currently only --stdio
           output supports this feature.

       --header-only
           Show only perf.data header (forces --stdio).

       --itrace
           Options for decoding instruction tracing data. The options are:

               i       synthesize instructions events
               b       synthesize branches events
               c       synthesize branches events (calls only)
               r       synthesize branches events (returns only)
               x       synthesize transactions events
               e       synthesize error events
               d       create a debug log
               g       synthesize a call chain (use with i or x)
               l       synthesize last branch entries (use with i or x)

               The default is all events i.e. the same as --itrace=ibxe

               In addition, the period (default 100000) for instructions events
               can be specified in units of:

               i       instructions
               t       ticks
               ms      milliseconds
               us      microseconds
               ns      nanoseconds (default)

               Also the call chain size (default 16, max. 1024) for instructions or
               transactions events can be specified.

               Also the number of last branch entries (default 64, max. 1024) for
               instructions or transactions events can be specified.

               To disable decoding entirely, use --no-itrace.

       --full-source-path
           Show the full path for source files for srcline output.

       --show-ref-call-graph
           When multiple events are sampled, it may not be needed to collect callgraphs for all of them. The
           sample sites are usually nearby, and it’s enough to collect the callgraphs on a reference event. So
           user can use "call-graph=no" event modifier to disable callgraph for other events to reduce the
           overhead. However, perf report cannot show callgraphs for the event which disable the callgraph. This
           option extends the perf report to show reference callgraphs, which collected by reference event, in
           no callgraph event.

       --socket-filter
           Only report the samples on the processor socket that match with this filter

OVERHEAD CALCULATION

       The overhead can be shown in two columns as Children and Self when perf collects callchains. The self
       overhead is simply calculated by adding all period values of the entry - usually a function (symbol).
       This is the value that perf shows traditionally and sum of all the self overhead values should be 100%.

       The children overhead is calculated by adding all period values of the child functions so that it can
       show the total overhead of the higher level functions even if they don’t directly execute much. Children
       here means functions that are called from another (parent) function.

       It might be confusing that the sum of all the children overhead values exceeds 100% since each of them is
       already an accumulation of self overhead of its child functions. But with this enabled, users can find
       which function has the most overhead even if samples are spread over the children.

       Consider the following example; there are three functions like below.

           .ft C
           void foo(void) {
               /* do something */
           }

           void bar(void) {
               /* do something */
               foo();
           }

           int main(void) {
               bar()
               return 0;
           }
           .ft

       In this case foo is a child of bar, and bar is an immediate child of main so foo also is a child of main.
       In other words, main is a parent of foo and bar, and bar is a parent of foo.

       Suppose all samples are recorded in foo and bar only. When it’s recorded with callchains the output will
       show something like below in the usual (self-overhead-only) output of perf report:

           .ft C
           Overhead  Symbol
           ........  .....................
             60.00%  foo
                     |
                     --- foo
                         bar
                         main
                         __libc_start_main

             40.00%  bar
                     |
                     --- bar
                         main
                         __libc_start_main
           .ft

       When the --children option is enabled, the self overhead values of child functions (i.e. foo and bar) are
       added to the parents to calculate the children overhead. In this case the report could be displayed as:

           .ft C
           Children      Self  Symbol
           ........  ........  ....................
            100.00%     0.00%  __libc_start_main
                     |
                     --- __libc_start_main

            100.00%     0.00%  main
                     |
                     --- main
                         __libc_start_main

            100.00%    40.00%  bar
                     |
                     --- bar
                         main
                         __libc_start_main

             60.00%    60.00%  foo
                     |
                     --- foo
                         bar
                         main
                         __libc_start_main
           .ft

       In the above output, the self overhead of foo (60%) was add to the children overhead of bar, main and
       __libc_start_main. Likewise, the self overhead of bar (40%) was added to the children overhead of main
       and \_\_libc_start_main.

       So \_\_libc_start_main and main are shown first since they have same (100%) children overhead (even
       though they have zero self overhead) and they are the parents of foo and bar.

       Since v3.16 the children overhead is shown by default and the output is sorted by its values. The
       children overhead is disabled by specifying --no-children option on the command line or by adding
       report.children = false or top.children = false in the perf config file.

SEE ALSO

       perf-stat(1), perf-annotate(1)