From 13e0c844fa097f657bd8204fd574477c34f47a0c Mon Sep 17 00:00:00 2001 From: Kan Liang Date: Thu, 19 Mar 2020 13:25:15 -0700 Subject: perf top: 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. The option must be used with --call-graph lbr. Signed-off-by: Kan Liang Reviewed-by: Andi Kleen Acked-by: Jiri Olsa Tested-by: Arnaldo Carvalho de Melo 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/20200319202517.23423-16-kan.liang@linux.intel.com Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/builtin-top.c | 11 +++++++++++ 1 file changed, 11 insertions(+) (limited to 'tools/perf/builtin-top.c') diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c index 289cf83e658a..6b067a5ba1d5 100644 --- a/tools/perf/builtin-top.c +++ b/tools/perf/builtin-top.c @@ -33,6 +33,7 @@ #include "util/map.h" #include "util/mmap.h" #include "util/session.h" +#include "util/thread.h" #include "util/symbol.h" #include "util/synthetic-events.h" #include "util/top.h" @@ -775,6 +776,9 @@ static void perf_event__process_sample(struct perf_tool *tool, if (machine__resolve(machine, &al, sample) < 0) return; + if (top->stitch_lbr) + al.thread->lbr_stitch_enable = true; + if (!machine->kptr_restrict_warned && symbol_conf.kptr_restrict && al.cpumode == PERF_RECORD_MISC_KERNEL) { @@ -1571,6 +1575,8 @@ int cmd_top(int argc, const char **argv) "Sort the output by the event at the index n in group. " "If n is invalid, sort by the first event. " "WARNING: should be used on grouped events."), + OPT_BOOLEAN(0, "stitch-lbr", &top.stitch_lbr, + "Enable LBR callgraph stitching approach"), OPTS_EVSWITCH(&top.evswitch), OPT_END() }; @@ -1640,6 +1646,11 @@ int cmd_top(int argc, const char **argv) } } + if (top.stitch_lbr && !(callchain_param.record_mode == CALLCHAIN_LBR)) { + pr_err("Error: --stitch-lbr must be used with --call-graph lbr\n"); + goto out_delete_evlist; + } + if (opts->branch_stack && callchain_param.enabled) symbol_conf.show_branchflag_count = true; -- cgit v1.2.3-59-g8ed1b