From d80da766d181555d0c846298b8c619c384c7d179 Mon Sep 17 00:00:00 2001 From: Kan Liang Date: Thu, 19 Mar 2020 13:25:16 -0700 Subject: perf c2c: Add option to enable the LBR stitching approach With the LBR stitching approach, the reconstructed LBR call stack can break the HW limitation. However, it may reconstruct invalid call stacks in some cases, e.g. exception handing such as setjmp/longjmp. Also, it may impact the processing time especially when the number of samples with stitched LBRs are huge. Add an option to enable the approach. Signed-off-by: Kan Liang Reviewed-by: Andi Kleen Acked-by: Jiri Olsa Cc: Adrian Hunter Cc: Alexey Budankov Cc: Mathieu Poirier Cc: Michael Ellerman Cc: Namhyung Kim Cc: Pavel Gerasimov Cc: Peter Zijlstra Cc: Ravi Bangoria Cc: Stephane Eranian Cc: Vitaly Slobodskoy Link: http://lore.kernel.org/lkml/20200319202517.23423-17-kan.liang@linux.intel.com Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/builtin-c2c.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) (limited to 'tools/perf/builtin-c2c.c') diff --git a/tools/perf/builtin-c2c.c b/tools/perf/builtin-c2c.c index 246ac0b4d54f..0d544c4fb4be 100644 --- a/tools/perf/builtin-c2c.c +++ b/tools/perf/builtin-c2c.c @@ -95,6 +95,7 @@ struct perf_c2c { bool use_stdio; bool stats_only; bool symbol_full; + bool stitch_lbr; /* HITM shared clines stats */ struct c2c_stats hitm_stats; @@ -273,6 +274,9 @@ static int process_sample_event(struct perf_tool *tool __maybe_unused, return -1; } + if (c2c.stitch_lbr) + al.thread->lbr_stitch_enable = true; + ret = sample__resolve_callchain(sample, &callchain_cursor, NULL, evsel, &al, sysctl_perf_event_max_stack); if (ret) @@ -2601,6 +2605,12 @@ static int setup_callchain(struct evlist *evlist) } } + if (c2c.stitch_lbr && (mode != CALLCHAIN_LBR)) { + ui__warning("Can't find LBR callchain. Switch off --stitch-lbr.\n" + "Please apply --call-graph lbr when recording.\n"); + c2c.stitch_lbr = false; + } + callchain_param.record_mode = mode; callchain_param.min_percent = 0; return 0; @@ -2752,6 +2762,8 @@ static int perf_c2c__report(int argc, const char **argv) OPT_STRING('c', "coalesce", &coalesce, "coalesce fields", "coalesce fields: pid,tid,iaddr,dso"), OPT_BOOLEAN('f', "force", &symbol_conf.force, "don't complain, do it"), + OPT_BOOLEAN(0, "stitch-lbr", &c2c.stitch_lbr, + "Enable LBR callgraph stitching approach"), OPT_PARENT(c2c_options), OPT_END() }; -- cgit v1.2.3