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authorKan Liang <kan.liang@intel.com>2015-08-11 06:30:49 -0400
committerArnaldo Carvalho de Melo <acme@redhat.com>2015-08-12 13:20:28 -0300
commit9e207ddfa20781e56465ce9a537f0a377c9d34fb (patch)
tree8eea5617ff1c5e997a591ef8733aae16e1668aee /tools/perf/Documentation/perf-report.txt
parentf9db0d0f1b2cf030083c83d3ed3a4bbae6bdc8b7 (diff)
downloadlinux-9e207ddfa20781e56465ce9a537f0a377c9d34fb.tar.gz
perf report: Show call graph from reference events
Introduce --show-ref-call-graph for perf report to print reference callgraph for no callgraph event. Here is an example. perf report --show-ref-call-graph --stdio # To display the perf.data header info, please use --header/--header-only options. # # # Total Lost Samples: 0 # # Samples: 5 of event 'cpu/cpu-cycles,call-graph=fp/' # Event count (approx.): 144985 # # Children Self Command Shared Object Symbol # ........ ........ ....... ................ ........................................ # 72.30% 0.00% sleep [kernel.vmlinux] [k] entry_SYSCALL_64_fastpath | ---entry_SYSCALL_64_fastpath | |--22.62%-- __GI___libc_nanosleep --77.38%-- [...] ...... # Samples: 6 of event 'cpu/instructions,call-graph=no/', show reference callgraph # Event count (approx.): 172780 # # Children Self Command Shared Object Symbol # ........ ........ ....... ................ ........................................ # 73.16% 0.00% sleep [kernel.vmlinux] [k] entry_SYSCALL_64_fastpath | ---entry_SYSCALL_64_fastpath | |--31.44%-- __GI___libc_nanosleep --68.56%-- [...] Signed-off-by: Kan Liang <kan.liang@intel.com> Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Namhyung Kim <namhyung@kernel.org> Link: http://lkml.kernel.org/r/1439289050-40510-3-git-send-email-kan.liang@intel.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools/perf/Documentation/perf-report.txt')
-rw-r--r--tools/perf/Documentation/perf-report.txt11
1 files changed, 11 insertions, 0 deletions
diff --git a/tools/perf/Documentation/perf-report.txt b/tools/perf/Documentation/perf-report.txt
index 7b07d19e2d54..a18ba757a0ed 100644
--- a/tools/perf/Documentation/perf-report.txt
+++ b/tools/perf/Documentation/perf-report.txt
@@ -359,6 +359,17 @@ OPTIONS
--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.
+
include::callchain-overhead-calculation.txt[]
SEE ALSO