From 442ad2254ac56b39870c0cfed96d500921fea5d5 Mon Sep 17 00:00:00 2001 From: Adrian Hunter Date: Mon, 29 Jun 2020 12:19:51 +0300 Subject: perf record: Fix duplicated sideband events with Intel PT system wide tracing Commit 0a892c1c9472 ("perf record: Add dummy event during system wide synthesis") reveals an issue with Intel PT system wide tracing. Specifically that Intel PT already adds a dummy tracking event, and it is not the first event. Adding another dummy tracking event causes duplicated sideband events. Fix by checking for an existing dummy tracking event first. Example showing duplicated switch events: Before: # perf record -a -e intel_pt//u uname Linux [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.895 MB perf.data ] # perf script --no-itrace --show-switch-events | head swapper 0 [007] 6390.516222: PERF_RECORD_SWITCH_CPU_WIDE OUT preempt next pid/tid: 11/11 swapper 0 [007] 6390.516222: PERF_RECORD_SWITCH_CPU_WIDE OUT preempt next pid/tid: 11/11 rcu_sched 11 [007] 6390.516223: PERF_RECORD_SWITCH_CPU_WIDE IN prev pid/tid: 0/0 rcu_sched 11 [007] 6390.516224: PERF_RECORD_SWITCH_CPU_WIDE IN prev pid/tid: 0/0 rcu_sched 11 [007] 6390.516227: PERF_RECORD_SWITCH_CPU_WIDE OUT next pid/tid: 0/0 rcu_sched 11 [007] 6390.516227: PERF_RECORD_SWITCH_CPU_WIDE OUT next pid/tid: 0/0 swapper 0 [007] 6390.516228: PERF_RECORD_SWITCH_CPU_WIDE IN prev pid/tid: 11/11 swapper 0 [007] 6390.516228: PERF_RECORD_SWITCH_CPU_WIDE IN prev pid/tid: 11/11 swapper 0 [002] 6390.516415: PERF_RECORD_SWITCH_CPU_WIDE OUT preempt next pid/tid: 5556/5559 swapper 0 [002] 6390.516416: PERF_RECORD_SWITCH_CPU_WIDE OUT preempt next pid/tid: 5556/5559 After: # perf record -a -e intel_pt//u uname Linux [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.868 MB perf.data ] # perf script --no-itrace --show-switch-events | head swapper 0 [005] 6450.567013: PERF_RECORD_SWITCH_CPU_WIDE OUT preempt next pid/tid: 7179/7181 perf 7181 [005] 6450.567014: PERF_RECORD_SWITCH_CPU_WIDE IN prev pid/tid: 0/0 perf 7181 [005] 6450.567028: PERF_RECORD_SWITCH_CPU_WIDE OUT next pid/tid: 0/0 swapper 0 [005] 6450.567029: PERF_RECORD_SWITCH_CPU_WIDE IN prev pid/tid: 7179/7181 swapper 0 [005] 6450.571699: PERF_RECORD_SWITCH_CPU_WIDE OUT preempt next pid/tid: 11/11 rcu_sched 11 [005] 6450.571700: PERF_RECORD_SWITCH_CPU_WIDE IN prev pid/tid: 0/0 rcu_sched 11 [005] 6450.571702: PERF_RECORD_SWITCH_CPU_WIDE OUT next pid/tid: 0/0 swapper 0 [005] 6450.571703: PERF_RECORD_SWITCH_CPU_WIDE IN prev pid/tid: 11/11 swapper 0 [005] 6450.579703: PERF_RECORD_SWITCH_CPU_WIDE OUT preempt next pid/tid: 11/11 rcu_sched 11 [005] 6450.579704: PERF_RECORD_SWITCH_CPU_WIDE IN prev pid/tid: 0/0 Signed-off-by: Adrian Hunter Tested-by: Arnaldo Carvalho de Melo Cc: Jiri Olsa Link: http://lore.kernel.org/lkml/20200629091955.17090-3-adrian.hunter@intel.com Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/builtin-record.c | 18 +++++++++--------- 1 file changed, 9 insertions(+), 9 deletions(-) (limited to 'tools/perf/builtin-record.c') diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c index e108d90ae2ed..a37e7910e9e9 100644 --- a/tools/perf/builtin-record.c +++ b/tools/perf/builtin-record.c @@ -852,20 +852,20 @@ static int record__open(struct record *rec) * event synthesis. */ if (opts->initial_delay || target__has_cpu(&opts->target)) { - if (perf_evlist__add_dummy(evlist)) - return -ENOMEM; + pos = perf_evlist__get_tracking_event(evlist); + if (!evsel__is_dummy_event(pos)) { + /* Set up dummy event. */ + if (perf_evlist__add_dummy(evlist)) + return -ENOMEM; + pos = evlist__last(evlist); + perf_evlist__set_tracking_event(evlist, pos); + } - /* Disable tracking of mmaps on lead event. */ - pos = evlist__first(evlist); - pos->tracking = 0; - /* Set up dummy event. */ - pos = evlist__last(evlist); - pos->tracking = 1; /* * Enable the dummy event when the process is forked for * initial_delay, immediately for system wide. */ - if (opts->initial_delay) + if (opts->initial_delay && !pos->immediate) pos->core.attr.enable_on_exec = 1; else pos->immediate = 1; -- cgit v1.2.3