From 0fba226548501099616b7f1cc73c853ffd560511 Mon Sep 17 00:00:00 2001 From: Namhyung Kim Date: Thu, 6 Apr 2023 14:06:10 -0700 Subject: [PATCH] perf lock contention: Revise needs_callstack() condition It needs callstacks for two reasons: * for stack aggregation mode, the map key is the stack id and it can also show the full stack traces when -v is used * for other aggregation modes, the stack filter can be used to limit lock contentions from known call paths The -v option is meaningful (in terms of stack trace) only for stack aggregation mode, so it should not set the save_callstack for other mode like with -t or -l options. I've noticed this with the following command line: $ sudo ./perf lock con -ablv -E 3 -M 16 -- ./perf bench sched messaging ... contended total wait max wait avg wait address symbol 88 4.59 ms 108.07 us 52.13 us ffff935757f46ec0 (spinlock) 33 905.22 us 73.67 us 27.43 us ffff935757f41700 (spinlock) 28 703.69 us 79.28 us 25.13 us ffff938a3d9b0c80 rq_lock (spinlock) === output for debug === bad: 12272, total: 12421 bad rate: 98.80 % histogram of failure reasons task: 8285 stack: 3987 <---------- here time: 0 data: 0 It should not have any failure on stacks since it doesn't use it. No functional change intended. Signed-off-by: Namhyung Kim Acked-by: Ian Rogers Cc: Adrian Hunter Cc: Hao Luo Cc: Ingo Molnar Cc: Jiri Olsa Cc: Juri Lelli Cc: Peter Zijlstra Cc: Song Liu Cc: bpf@vger.kernel.org Link: https://lore.kernel.org/r/20230406210611.1622492-2-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/builtin-lock.c | 2 +- tools/perf/util/bpf_lock_contention.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/tools/perf/builtin-lock.c b/tools/perf/builtin-lock.c index 7742fa2..4e24351 100644 --- a/tools/perf/builtin-lock.c +++ b/tools/perf/builtin-lock.c @@ -77,7 +77,7 @@ static enum lock_aggr_mode aggr_mode = LOCK_AGGR_ADDR; static bool needs_callstack(void) { - return verbose > 0 || !list_empty(&callstack_filters); + return !list_empty(&callstack_filters); } static struct thread_stat *thread_stat_find(u32 tid) diff --git a/tools/perf/util/bpf_lock_contention.c b/tools/perf/util/bpf_lock_contention.c index ea4f697..9e20fa8 100644 --- a/tools/perf/util/bpf_lock_contention.c +++ b/tools/perf/util/bpf_lock_contention.c @@ -346,7 +346,7 @@ int lock_contention_read(struct lock_contention *con) if (data.count) st->avg_wait_time = data.total_time / data.count; - if (con->save_callstack) { + if (con->aggr_mode == LOCK_AGGR_CALLER && verbose > 0) { st->callstack = memdup(stack_trace, stack_size); if (st->callstack == NULL) break; -- 2.7.4