linux/tools/perf/Documentation/perf-report.txt

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perf-report(1)
==============
NAME
----
perf-report - Read perf.data (created by perf record) and display the profile
SYNOPSIS
--------
[verse]
'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)
-d::
--dsos=::
Only consider symbols in these dsos. CSV that understands
file://filename entries.
-n::
--show-nr-samples::
Show the number of samples for each symbol
--showcpuutilization::
Show sample percentage for different cpu modes.
-T::
--threads::
Show per-thread event counters
-c::
--comms=::
Only consider symbols in these comms. CSV that understands
file://filename entries.
-S::
--symbols=::
Only consider these symbols. CSV that understands
file://filename entries.
--symbol-filter=::
Only show symbols that match (partially) with this filter.
-U::
--hide-unresolved::
Only display entries resolved to a symbol.
perf diff: Use perf_session__fprintf_hists just like 'perf record' That means that almost everything you can do with 'perf report' can be done with 'perf diff', for instance: $ perf record -f find / > /dev/null [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.062 MB perf.data (~2699 samples) ] $ perf record -f find / > /dev/null [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.062 MB perf.data (~2687 samples) ] perf diff | head -8 9.02% +1.00% find libc-2.10.1.so [.] _IO_vfprintf_internal 2.91% -1.00% find [kernel] [k] __kmalloc 2.85% -1.00% find [kernel] [k] ext4_htree_store_dirent 1.99% -1.00% find [kernel] [k] _atomic_dec_and_lock 2.44% find [kernel] [k] half_md4_transform $ So if you want to zoom into libc: $ perf diff --dsos libc-2.10.1.so | head -8 37.34% find [.] _IO_vfprintf_internal 10.34% find [.] __GI_memmove 8.25% +2.00% find [.] _int_malloc 5.07% -1.00% find [.] __GI_mempcpy 7.62% +2.00% find [.] _int_free $ And if there were multiple commands using libc, it is also possible to aggregate them all by using --sort symbol: $ perf diff --dsos libc-2.10.1.so --sort symbol | head -8 37.34% [.] _IO_vfprintf_internal 10.34% [.] __GI_memmove 8.25% +2.00% [.] _int_malloc 5.07% -1.00% [.] __GI_mempcpy 7.62% +2.00% [.] _int_free $ The displacement column now is off by default, to use it: perf diff -m --dsos libc-2.10.1.so --sort symbol | head -8 37.34% [.] _IO_vfprintf_internal 10.34% [.] __GI_memmove 8.25% +2.00% [.] _int_malloc 5.07% -1.00% +2 [.] __GI_mempcpy 7.62% +2.00% -1 [.] _int_free $ Using -t/--field-separator can be used for scripting: $ perf diff -t, -m --dsos libc-2.10.1.so --sort symbol | head -8 37.34, , ,[.] _IO_vfprintf_internal 10.34, , ,[.] __GI_memmove 8.25,+2.00%, ,[.] _int_malloc 5.07,-1.00%, +2,[.] __GI_mempcpy 7.62,+2.00%, -1,[.] _int_free 6.99,+1.00%, -1,[.] _IO_new_file_xsputn 1.89,-2.00%, +4,[.] __readdir64 $ Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Frédéric Weisbecker <fweisbec@gmail.com> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Paul Mackerras <paulus@samba.org> LKML-Reference: <1260978567-550-1-git-send-email-acme@infradead.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-12-16 23:49:27 +08:00
-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, 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
- srcline: filename and line number executed at the time of sample. The
DWARF debugging info must be provided.
- 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.
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.
And default sort keys are changed to comm, dso_from, symbol_from, dso_to
and symbol_to, see '--branch-stack'.
perf diff: Use perf_session__fprintf_hists just like 'perf record' That means that almost everything you can do with 'perf report' can be done with 'perf diff', for instance: $ perf record -f find / > /dev/null [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.062 MB perf.data (~2699 samples) ] $ perf record -f find / > /dev/null [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.062 MB perf.data (~2687 samples) ] perf diff | head -8 9.02% +1.00% find libc-2.10.1.so [.] _IO_vfprintf_internal 2.91% -1.00% find [kernel] [k] __kmalloc 2.85% -1.00% find [kernel] [k] ext4_htree_store_dirent 1.99% -1.00% find [kernel] [k] _atomic_dec_and_lock 2.44% find [kernel] [k] half_md4_transform $ So if you want to zoom into libc: $ perf diff --dsos libc-2.10.1.so | head -8 37.34% find [.] _IO_vfprintf_internal 10.34% find [.] __GI_memmove 8.25% +2.00% find [.] _int_malloc 5.07% -1.00% find [.] __GI_mempcpy 7.62% +2.00% find [.] _int_free $ And if there were multiple commands using libc, it is also possible to aggregate them all by using --sort symbol: $ perf diff --dsos libc-2.10.1.so --sort symbol | head -8 37.34% [.] _IO_vfprintf_internal 10.34% [.] __GI_memmove 8.25% +2.00% [.] _int_malloc 5.07% -1.00% [.] __GI_mempcpy 7.62% +2.00% [.] _int_free $ The displacement column now is off by default, to use it: perf diff -m --dsos libc-2.10.1.so --sort symbol | head -8 37.34% [.] _IO_vfprintf_internal 10.34% [.] __GI_memmove 8.25% +2.00% [.] _int_malloc 5.07% -1.00% +2 [.] __GI_mempcpy 7.62% +2.00% -1 [.] _int_free $ Using -t/--field-separator can be used for scripting: $ perf diff -t, -m --dsos libc-2.10.1.so --sort symbol | head -8 37.34, , ,[.] _IO_vfprintf_internal 10.34, , ,[.] __GI_memmove 8.25,+2.00%, ,[.] _int_malloc 5.07,-1.00%, +2,[.] __GI_mempcpy 7.62,+2.00%, -1,[.] _int_free 6.99,+1.00%, -1,[.] _IO_new_file_xsputn 1.89,-2.00%, +4,[.] __readdir64 $ Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Frédéric Weisbecker <fweisbec@gmail.com> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Paul Mackerras <paulus@samba.org> LKML-Reference: <1260978567-550-1-git-send-email-acme@infradead.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-12-16 23:49:27 +08:00
-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.
perf report: Adjust column width to the values sampled Auto-adjust column width of perf report output to the longest occuring string length. Example: [acme@doppio pahole]$ perf report --sort comm,dso,symbol | head -13 12.79% pahole /usr/lib64/libdw-0.141.so [.] __libdw_find_attr 8.90% pahole /lib64/libc-2.10.1.so [.] _int_malloc 8.68% pahole /usr/lib64/libdw-0.141.so [.] __libdw_form_val_len 8.15% pahole /lib64/libc-2.10.1.so [.] __GI_strcmp 6.80% pahole /lib64/libc-2.10.1.so [.] __tsearch 5.54% pahole ./build/libdwarves.so.1.0.0 [.] tag__recode_dwarf_type [acme@doppio pahole]$ [acme@doppio pahole]$ perf report --sort comm,dso,symbol -d /lib64/libc-2.10.1.so | head -10 21.92% pahole /lib64/libc-2.10.1.so [.] _int_malloc 20.08% pahole /lib64/libc-2.10.1.so [.] __GI_strcmp 16.75% pahole /lib64/libc-2.10.1.so [.] __tsearch [acme@doppio pahole]$ Also add these extra options to control the new behaviour: -w, --field-width Force each column width to the provided list, for large terminal readability. -t, --field-separator: Use a special separator character and don't pad with spaces, replacing all occurances of this separator in symbol names (and other output) with a '.' character, that thus it's the only non valid separator. Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Paul Mackerras <paulus@samba.org> LKML-Reference: <20090711014728.GH3452@ghostprotocols.net> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-07-11 09:47:28 +08:00
-w::
--column-widths=<width[,width...]>::
perf report: Adjust column width to the values sampled Auto-adjust column width of perf report output to the longest occuring string length. Example: [acme@doppio pahole]$ perf report --sort comm,dso,symbol | head -13 12.79% pahole /usr/lib64/libdw-0.141.so [.] __libdw_find_attr 8.90% pahole /lib64/libc-2.10.1.so [.] _int_malloc 8.68% pahole /usr/lib64/libdw-0.141.so [.] __libdw_form_val_len 8.15% pahole /lib64/libc-2.10.1.so [.] __GI_strcmp 6.80% pahole /lib64/libc-2.10.1.so [.] __tsearch 5.54% pahole ./build/libdwarves.so.1.0.0 [.] tag__recode_dwarf_type [acme@doppio pahole]$ [acme@doppio pahole]$ perf report --sort comm,dso,symbol -d /lib64/libc-2.10.1.so | head -10 21.92% pahole /lib64/libc-2.10.1.so [.] _int_malloc 20.08% pahole /lib64/libc-2.10.1.so [.] __GI_strcmp 16.75% pahole /lib64/libc-2.10.1.so [.] __tsearch [acme@doppio pahole]$ Also add these extra options to control the new behaviour: -w, --field-width Force each column width to the provided list, for large terminal readability. -t, --field-separator: Use a special separator character and don't pad with spaces, replacing all occurances of this separator in symbol names (and other output) with a '.' character, that thus it's the only non valid separator. Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Paul Mackerras <paulus@samba.org> LKML-Reference: <20090711014728.GH3452@ghostprotocols.net> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-07-11 09:47:28 +08:00
Force each column width to the provided list, for large terminal
readability.
-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)
perf report: Adjust column width to the values sampled Auto-adjust column width of perf report output to the longest occuring string length. Example: [acme@doppio pahole]$ perf report --sort comm,dso,symbol | head -13 12.79% pahole /usr/lib64/libdw-0.141.so [.] __libdw_find_attr 8.90% pahole /lib64/libc-2.10.1.so [.] _int_malloc 8.68% pahole /usr/lib64/libdw-0.141.so [.] __libdw_form_val_len 8.15% pahole /lib64/libc-2.10.1.so [.] __GI_strcmp 6.80% pahole /lib64/libc-2.10.1.so [.] __tsearch 5.54% pahole ./build/libdwarves.so.1.0.0 [.] tag__recode_dwarf_type [acme@doppio pahole]$ [acme@doppio pahole]$ perf report --sort comm,dso,symbol -d /lib64/libc-2.10.1.so | head -10 21.92% pahole /lib64/libc-2.10.1.so [.] _int_malloc 20.08% pahole /lib64/libc-2.10.1.so [.] __GI_strcmp 16.75% pahole /lib64/libc-2.10.1.so [.] __tsearch [acme@doppio pahole]$ Also add these extra options to control the new behaviour: -w, --field-width Force each column width to the provided list, for large terminal readability. -t, --field-separator: Use a special separator character and don't pad with spaces, replacing all occurances of this separator in symbol names (and other output) with a '.' character, that thus it's the only non valid separator. Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Paul Mackerras <paulus@samba.org> LKML-Reference: <20090711014728.GH3452@ghostprotocols.net> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-07-11 09:47:28 +08:00
with a '.' character, that thus it's the only non valid separator.
-D::
--dump-raw-trace::
Dump raw trace in ASCII.
-g [type,min[,limit],order[,key]]::
--call-graph::
Display call chains using type, min percent threshold, optional print
limit and order.
type can be either:
- flat: single column, linear exposure of call chains.
- graph: use a graph tree, displaying absolute overhead rates.
- fractal: like graph, but displays relative rates. Each branch of
the tree is considered as a new profiled object. +
order can be either:
- callee: callee based call graph.
- caller: inverted caller based call graph.
key can be:
- function: compare on functions
- address: compare on individual code addresses
Default: fractal,0.5,callee,function.
perf report: Add --max-stack option to limit callchain stack scan When callgraph data was included in the perf data file, it may take a long time to scan all those data and merge them together especially if the stored callchains are long and the perf data file itself is large, like a Gbyte or so. The callchain stack is currently limited to PERF_MAX_STACK_DEPTH (127). This is a large value. Usually the callgraph data that developers are most interested in are the first few levels, the rests are usually not looked at. This patch adds a new --max-stack option to perf-report to limit the depth of callchain stack data to look at to reduce the time it takes for perf-report to finish its processing. It trades the presence of trailing stack information with faster speed. The following table shows the elapsed time of doing perf-report on a perf.data file of size 985,531,828 bytes. --max_stack Elapsed Time Output data size ----------- ------------ ---------------- not set 88.0s 124,422,651 64 87.5s 116,303,213 32 87.2s 112,023,804 16 86.6s 94,326,380 8 59.9s 33,697,248 4 40.7s 10,116,637 -g none 27.1s 2,555,810 Signed-off-by: Waiman Long <Waiman.Long@hp.com> Acked-by: David Ahern <dsahern@gmail.com> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Aswin Chandramouleeswaran <aswin@hp.com> Cc: David Ahern <dsahern@gmail.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Scott J Norton <scott.norton@hp.com> Cc: Stephane Eranian <eranian@google.com> Link: http://lkml.kernel.org/r/1382107129-2010-4-git-send-email-Waiman.Long@hp.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2013-10-18 22:38:48 +08:00
--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.
Default: 127
-G::
--inverted::
alias for inverted caller based call graph.
perf report/top: Add option to collapse undesired parts of call graph For example, in an application with an expensive function implemented with deeply nested recursive calls, the default call-graph presentation is dominated by the different callchains within that function. By ignoring these callees, we can collect the callchains leading into the function and compactly identify what to blame for expensive calls. For example, in this report the callers of garbage_collect() are scattered across the tree: $ perf report -d ruby 2>- | grep -m10 ^[^#]*[a-z] 22.03% ruby [.] gc_mark --- gc_mark |--59.40%-- mark_keyvalue | st_foreach | gc_mark_children | |--99.75%-- rb_gc_mark | | rb_vm_mark | | gc_mark_children | | gc_marks | | |--99.00%-- garbage_collect If we ignore the callees of garbage_collect(), its callers are coalesced: $ perf report --ignore-callees garbage_collect -d ruby 2>- | grep -m10 ^[^#]*[a-z] 72.92% ruby [.] garbage_collect --- garbage_collect vm_xmalloc |--47.08%-- ruby_xmalloc | st_insert2 | rb_hash_aset | |--98.45%-- features_index_add | | rb_provide_feature | | rb_require_safe | | vm_call_method Signed-off-by: Greg Price <price@mit.edu> Tested-by: Jiri Olsa <jolsa@redhat.com> Cc: David Ahern <dsahern@gmail.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/20130623031720.GW22203@biohazard-cafe.mit.edu Link: http://lkml.kernel.org/r/20130708115746.GO22203@biohazard-cafe.mit.edu Cc: Fengguang Wu <fengguang.wu@intel.com> [ remove spaces at beginning of line, reported by Fengguang Wu ] Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2012-12-07 13:48:05 +08:00
--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.
perf tools: Make perf.data more self-descriptive (v8) The goal of this patch is to include more information about the host environment into the perf.data so it is more self-descriptive. Overtime, profiles are captured on various machines and it becomes hard to track what was recorded, on what machine and when. This patch provides a way to solve this by extending the perf.data file with basic information about the host machine. To add those extensions, we leverage the feature bits capabilities of the perf.data format. The change is backward compatible with existing perf.data files. We define the following useful new extensions: - HEADER_HOSTNAME: the hostname - HEADER_OSRELEASE: the kernel release number - HEADER_ARCH: the hw architecture - HEADER_CPUDESC: generic CPU description - HEADER_NRCPUS: number of online/avail cpus - HEADER_CMDLINE: perf command line - HEADER_VERSION: perf version - HEADER_TOPOLOGY: cpu topology - HEADER_EVENT_DESC: full event description (attrs) - HEADER_CPUID: easy-to-parse low level CPU identication The small granularity for the entries is to make it easier to extend without breaking backward compatiblity. Many entries are provided as ASCII strings. Perf report/script have been modified to print the basic information as easy-to-parse ASCII strings. Extended information about CPU and NUMA topology may be requested with the -I option. Thanks to David Ahern for reviewing and testing the many versions of this patch. $ perf report --stdio # ======== # captured on : Mon Sep 26 15:22:14 2011 # hostname : quad # os release : 3.1.0-rc4-tip # perf version : 3.1.0-rc4 # arch : x86_64 # nrcpus online : 4 # nrcpus avail : 4 # cpudesc : Intel(R) Core(TM)2 Quad CPU Q6600 @ 2.40GHz # cpuid : GenuineIntel,6,15,11 # total memory : 8105360 kB # cmdline : /home/eranian/perfmon/official/tip/build/tools/perf/perf record date # event : name = cycles, type = 0, config = 0x0, config1 = 0x0, config2 = 0x0, excl_usr = 0, excl_kern = 0, id = { 29, 30, 31, # HEADER_CPU_TOPOLOGY info available, use -I to display # HEADER_NUMA_TOPOLOGY info available, use -I to display # ======== # ... $ perf report --stdio -I # ======== # captured on : Mon Sep 26 15:22:14 2011 # hostname : quad # os release : 3.1.0-rc4-tip # perf version : 3.1.0-rc4 # arch : x86_64 # nrcpus online : 4 # nrcpus avail : 4 # cpudesc : Intel(R) Core(TM)2 Quad CPU Q6600 @ 2.40GHz # cpuid : GenuineIntel,6,15,11 # total memory : 8105360 kB # cmdline : /home/eranian/perfmon/official/tip/build/tools/perf/perf record date # event : name = cycles, type = 0, config = 0x0, config1 = 0x0, config2 = 0x0, excl_usr = 0, excl_kern = 0, id = { 29, 30, 31, # sibling cores : 0-3 # sibling threads : 0 # sibling threads : 1 # sibling threads : 2 # sibling threads : 3 # node0 meminfo : total = 8320608 kB, free = 7571024 kB # node0 cpu list : 0-3 # ======== # ... Reviewed-by: David Ahern <dsahern@gmail.com> Tested-by: David Ahern <dsahern@gmail.com> Cc: David Ahern <dsahern@gmail.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Robert Richter <robert.richter@amd.com> Cc: Andi Kleen <ak@linux.intel.com> Link: http://lkml.kernel.org/r/20110930134040.GA5575@quad Signed-off-by: Stephane Eranian <eranian@google.com> [ committer notes: Use --show-info in the tools as was in the docs, rename perf_header_fprintf_info to perf_file_section__fprintf_info, fixup conflict with f69b64f7 "perf: Support setting the disassembler style" ] Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2011-09-30 21:40:40 +08:00
-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.
perf report: Add support for taken branch sampling This patch adds support for taken branch sampling, i.e, the PERF_SAMPLE_BRANCH_STACK feature to perf report. In other words, to display histograms based on taken branches rather than executed instructions addresses. The new option is called -b and it takes no argument. To generate meaningful output, the perf.data must have been obtained using perf record -b xxx ... where xxx is a branch filter option. The output shows symbols, modules, sorted by 'who branches where' the most often. The percentages reported in the first column refer to the total number of branches captured and not the usual number of samples. Here is a quick example. Here branchy is simple test program which looks as follows: void f2(void) {} void f3(void) {} void f1(unsigned long n) { if (n & 1UL) f2(); else f3(); } int main(void) { unsigned long i; for (i=0; i < N; i++) f1(i); return 0; } Here is the output captured on Nehalem, if we are only interested in user level function calls. $ perf record -b any_call,u -e cycles:u branchy $ perf report -b --sort=symbol 52.34% [.] main [.] f1 24.04% [.] f1 [.] f3 23.60% [.] f1 [.] f2 0.01% [k] _IO_new_file_xsputn [k] _IO_file_overflow 0.01% [k] _IO_vfprintf_internal [k] _IO_new_file_xsputn 0.01% [k] _IO_vfprintf_internal [k] strchrnul 0.01% [k] __printf [k] _IO_vfprintf_internal 0.01% [k] main [k] __printf About half (52%) of the call branches captured are from main() -> f1(). The second half (24%+23%) is split in two equal shares between f1() -> f2(), f1() ->f3(). The output is as expected given the code. It should be noted, that using -b in perf record does not eliminate information in the perf.data file. Consequently, a typical profile can also be obtained by perf report by simply not using its -b option. It is possible to sort on branch related columns: - dso_from, symbol_from - dso_to, symbol_to - mispredict Signed-off-by: Roberto Agostino Vitillo <ravitillo@lbl.gov> Signed-off-by: Stephane Eranian <eranian@google.com> Cc: peterz@infradead.org Cc: acme@redhat.com Cc: robert.richter@amd.com Cc: ming.m.lin@intel.com Cc: andi@firstfloor.org Cc: asharma@fb.com Cc: vweaver1@eecs.utk.edu Cc: khandual@linux.vnet.ibm.com Cc: dsahern@gmail.com Link: http://lkml.kernel.org/r/1328826068-11713-14-git-send-email-eranian@google.com Signed-off-by: Ingo Molnar <mingo@elte.hu>
2012-02-10 06:21:03 +08:00
-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.
perf report: Add support for taken branch sampling This patch adds support for taken branch sampling, i.e, the PERF_SAMPLE_BRANCH_STACK feature to perf report. In other words, to display histograms based on taken branches rather than executed instructions addresses. The new option is called -b and it takes no argument. To generate meaningful output, the perf.data must have been obtained using perf record -b xxx ... where xxx is a branch filter option. The output shows symbols, modules, sorted by 'who branches where' the most often. The percentages reported in the first column refer to the total number of branches captured and not the usual number of samples. Here is a quick example. Here branchy is simple test program which looks as follows: void f2(void) {} void f3(void) {} void f1(unsigned long n) { if (n & 1UL) f2(); else f3(); } int main(void) { unsigned long i; for (i=0; i < N; i++) f1(i); return 0; } Here is the output captured on Nehalem, if we are only interested in user level function calls. $ perf record -b any_call,u -e cycles:u branchy $ perf report -b --sort=symbol 52.34% [.] main [.] f1 24.04% [.] f1 [.] f3 23.60% [.] f1 [.] f2 0.01% [k] _IO_new_file_xsputn [k] _IO_file_overflow 0.01% [k] _IO_vfprintf_internal [k] _IO_new_file_xsputn 0.01% [k] _IO_vfprintf_internal [k] strchrnul 0.01% [k] __printf [k] _IO_vfprintf_internal 0.01% [k] main [k] __printf About half (52%) of the call branches captured are from main() -> f1(). The second half (24%+23%) is split in two equal shares between f1() -> f2(), f1() ->f3(). The output is as expected given the code. It should be noted, that using -b in perf record does not eliminate information in the perf.data file. Consequently, a typical profile can also be obtained by perf report by simply not using its -b option. It is possible to sort on branch related columns: - dso_from, symbol_from - dso_to, symbol_to - mispredict Signed-off-by: Roberto Agostino Vitillo <ravitillo@lbl.gov> Signed-off-by: Stephane Eranian <eranian@google.com> Cc: peterz@infradead.org Cc: acme@redhat.com Cc: robert.richter@amd.com Cc: ming.m.lin@intel.com Cc: andi@firstfloor.org Cc: asharma@fb.com Cc: vweaver1@eecs.utk.edu Cc: khandual@linux.vnet.ibm.com Cc: dsahern@gmail.com Link: http://lkml.kernel.org/r/1328826068-11713-14-git-send-email-eranian@google.com Signed-off-by: Ingo Molnar <mingo@elte.hu>
2012-02-10 06:21:03 +08:00
--objdump=<path>::
Path to objdump binary.
2013-01-22 17:09:45 +08:00
--group::
Show event group information together.
--demangle::
Demangle symbol names to human readable form. It's enabled by default,
disable with --no-demangle.
--percent-limit::
Do not show entries which have an overhead under that percent.
(Default: 0).
SEE ALSO
--------
linkperf:perf-stat[1], linkperf:perf-annotate[1]