From 445a625a66b15f7f8fbe70dea27269aa85c87bdf Mon Sep 17 00:00:00 2001 From: Namhyung Kim Date: Wed, 24 Jun 2026 13:58:28 -0700 Subject: [PATCH] perf timechart: Generate backtrace only if needed The backtrace was used by sched-switch and sched-wakeup only. No need to call cat_backtrace() in the process_sample_event(). Let's pass NULL backtrace and generate it from the sched events. As it needs a pointer to the 'machine', let's save the session in the timechart struct and use the host machine of the session instead of passing the pointer to all handlers. It should be fine to assume the host machine as timechart command doesn't deal with guest machines and there's no way to get tracepoints from the guest events. Signed-off-by: Namhyung Kim --- tools/perf/builtin-timechart.c | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) diff --git a/tools/perf/builtin-timechart.c b/tools/perf/builtin-timechart.c index dafd361ecf9d..337ae547d008 100644 --- a/tools/perf/builtin-timechart.c +++ b/tools/perf/builtin-timechart.c @@ -56,6 +56,7 @@ struct timechart { struct per_pid *all_data; struct power_event *power_events; struct wake_event *wake_events; + struct perf_session *session; int proc_num; unsigned int numcpus; u64 min_freq, /* Lowest CPU frequency seen */ @@ -578,7 +579,7 @@ typedef int (*tracepoint_handler)(struct timechart *tchart, static int process_sample_event(const struct perf_tool *tool, union perf_event *event __maybe_unused, struct perf_sample *sample, - struct machine *machine) + struct machine *machine __maybe_unused) { struct timechart *tchart = container_of(tool, struct timechart, tool); struct evsel *evsel = sample->evsel; @@ -593,10 +594,8 @@ static int process_sample_event(const struct perf_tool *tool, if (evsel->handler != NULL) { tracepoint_handler f = evsel->handler; - char *backtrace = cat_backtrace(sample, machine); - ret = f(tchart, sample, backtrace); - free(backtrace); + ret = f(tchart, sample, NULL); } return ret; @@ -656,7 +655,10 @@ process_sample_sched_wakeup(struct timechart *tchart, sample->file_offset, sample->cpu); return -1; } + + backtrace = cat_backtrace(sample, &tchart->session->machines.host); sched_wakeup(tchart, sample->cpu, sample->time, waker, wakee, flags, backtrace); + free((char *)backtrace); return 0; } @@ -675,8 +677,11 @@ process_sample_sched_switch(struct timechart *tchart, sample->file_offset, sample->cpu); return -1; } + + backtrace = cat_backtrace(sample, &tchart->session->machines.host); sched_switch(tchart, sample->cpu, sample->time, prev_pid, next_pid, prev_state, backtrace); + free((char *)backtrace); return 0; } @@ -1661,6 +1666,7 @@ static int __cmd_timechart(struct timechart *tchart, const char *output_name) if (IS_ERR(session)) return PTR_ERR(session); + tchart->session = session; symbol__init(perf_session__env(session)); (void)perf_header__process_sections(&session->header,