From 16b4b4e1a0038365a6734a4f50aba77e57865c8e Mon Sep 17 00:00:00 2001 From: Adrian Hunter Date: Thu, 28 May 2020 15:08:58 +0300 Subject: perf record: Respect --no-switch-events Context switch events are added automatically by Intel PT and Coresight. Make it possible to suppress them. That is useful for tracing the scheduler without the disturbance that the switch event processing creates. Example: Prerequisites: $ which perf ~/bin/perf $ sudo setcap "cap_sys_rawio,cap_sys_admin,cap_sys_ptrace,cap_syslog,cap_ipc_lock=ep" ~/bin/perf $ sudo chmod +r /proc/kcore Before: $ perf record --no-switch-events --kcore -a -e intel_pt//k -- sleep 0.001 [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.938 MB perf.data ] $ perf script -D | grep PERF_RECORD_SWITCH | wc -l 572 After: $ perf record --no-switch-events --kcore -a -e intel_pt//k -- sleep 0.001 Warning: Intel Processor Trace decoding will not be possible except for kernel tracing! [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.838 MB perf.data ] $ perf script -D | grep PERF_RECORD_SWITCH | wc -l 0 $ sudo chmod go-r /proc/kcore $ sudo setcap -r ~/bin/perf Signed-off-by: Adrian Hunter Tested-by: Arnaldo Carvalho de Melo Cc: Andi Kleen Cc: Jiri Olsa Cc: Mathieu Poirier Link: http://lore.kernel.org/lkml/20200528120859.21604-1-adrian.hunter@intel.com Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/arch/arm/util/cs-etm.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'tools/perf/arch/arm/util/cs-etm.c') diff --git a/tools/perf/arch/arm/util/cs-etm.c b/tools/perf/arch/arm/util/cs-etm.c index 607499b41bea..cea5e33d61d2 100644 --- a/tools/perf/arch/arm/util/cs-etm.c +++ b/tools/perf/arch/arm/util/cs-etm.c @@ -265,7 +265,8 @@ static int cs_etm_recording_options(struct auxtrace_record *itr, ptr->evlist = evlist; ptr->snapshot_mode = opts->auxtrace_snapshot_mode; - if (perf_can_record_switch_events()) + if (!record_opts__no_switch_events(opts) && + perf_can_record_switch_events()) opts->record_switch_events = true; evlist__for_each_entry(evlist, evsel) { -- cgit v1.2.3