Em Thu, May 28, 2020 at 03:08:58PM +0300, Adrian Hunter escreveu: > 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
Thanks, tested as root and applied. - Arnaldo > Signed-off-by: Adrian Hunter <[email protected]> > --- > tools/perf/Documentation/perf-record.txt | 4 +++- > tools/perf/arch/arm/util/cs-etm.c | 3 ++- > tools/perf/arch/x86/util/intel-pt.c | 3 ++- > tools/perf/builtin-record.c | 5 +++-- > tools/perf/util/record.h | 6 ++++++ > 5 files changed, 16 insertions(+), 5 deletions(-) > > diff --git a/tools/perf/Documentation/perf-record.txt > b/tools/perf/Documentation/perf-record.txt > index 561ef55743e2..97b1a866ab22 100644 > --- a/tools/perf/Documentation/perf-record.txt > +++ b/tools/perf/Documentation/perf-record.txt > @@ -458,7 +458,9 @@ This option sets the time out limit. The default value is > 500 ms. > > --switch-events:: > Record context switch events i.e. events of type PERF_RECORD_SWITCH or > -PERF_RECORD_SWITCH_CPU_WIDE. > +PERF_RECORD_SWITCH_CPU_WIDE. In some cases (e.g. Intel PT or CoreSight) > +switch events will be enabled automatically, which can be suppressed by > +by the option --no-switch-events. > > --clang-path=PATH:: > Path to clang binary to use for compiling BPF scriptlets. > 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) { > diff --git a/tools/perf/arch/x86/util/intel-pt.c > b/tools/perf/arch/x86/util/intel-pt.c > index fdb917fcf511..3fc547769707 100644 > --- a/tools/perf/arch/x86/util/intel-pt.c > +++ b/tools/perf/arch/x86/util/intel-pt.c > @@ -779,7 +779,8 @@ static int intel_pt_recording_options(struct > auxtrace_record *itr, > * Per-cpu recording needs sched_switch events to distinguish different > * threads. > */ > - if (have_timing_info && !perf_cpu_map__empty(cpus)) { > + if (have_timing_info && !perf_cpu_map__empty(cpus) && > + !record_opts__no_switch_events(opts)) { > if (perf_can_record_switch_events()) { > bool cpu_wide = !target__none(&opts->target) && > !target__has_task(&opts->target); > diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c > index 02d85f4e4517..dc6d5ba2fff8 100644 > --- a/tools/perf/builtin-record.c > +++ b/tools/perf/builtin-record.c > @@ -2490,8 +2490,9 @@ static struct option __record_options[] = { > "Record namespaces events"), > OPT_BOOLEAN(0, "all-cgroups", &record.opts.record_cgroup, > "Record cgroup events"), > - OPT_BOOLEAN(0, "switch-events", &record.opts.record_switch_events, > - "Record context switch events"), > + OPT_BOOLEAN_SET(0, "switch-events", &record.opts.record_switch_events, > + &record.opts.record_switch_events_set, > + "Record context switch events"), > OPT_BOOLEAN_FLAG(0, "all-kernel", &record.opts.all_kernel, > "Configure all used events to run in kernel space.", > PARSE_OPT_EXCLUSIVE), > diff --git a/tools/perf/util/record.h b/tools/perf/util/record.h > index dce6332f5071..84dbbc3f0204 100644 > --- a/tools/perf/util/record.h > +++ b/tools/perf/util/record.h > @@ -36,6 +36,7 @@ struct record_opts { > bool record_namespaces; > bool record_cgroup; > bool record_switch_events; > + bool record_switch_events_set; > bool all_kernel; > bool all_user; > bool kernel_callchains; > @@ -77,4 +78,9 @@ extern struct option *record_options; > > int record__parse_freq(const struct option *opt, const char *str, int unset); > > +static inline bool record_opts__no_switch_events(const struct record_opts > *opts) > +{ > + return opts->record_switch_events_set && !opts->record_switch_events; > +} > + > #endif // _PERF_RECORD_H > -- > 2.17.1 > -- - Arnaldo
