From 9e207ddfa20781e56465ce9a537f0a377c9d34fb Mon Sep 17 00:00:00 2001 From: Kan Liang Date: Tue, 11 Aug 2015 06:30:49 -0400 Subject: 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 Tested-by: Arnaldo Carvalho de Melo Cc: Andi Kleen Cc: Jiri Olsa Cc: Namhyung Kim Link: http://lkml.kernel.org/r/1439289050-40510-3-git-send-email-kan.liang@intel.com Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/Documentation/perf-report.txt | 11 +++++++++++ 1 file changed, 11 insertions(+) (limited to 'tools/perf/Documentation/perf-report.txt') 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 -- cgit v1.2.3