Messages in this thread | | | From | Ian Rogers <> | Date | Fri, 6 May 2022 01:34:13 -0700 | Subject | Re: [PATCH V1 13/23] perf evlist: Add evlist__add_system_wide_dummy() |
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On Fri, May 6, 2022 at 1:14 AM Adrian Hunter <adrian.hunter@intel.com> wrote: > > On 6/05/22 02:56, Ian Rogers wrote: > > On Thu, May 5, 2022 at 9:57 AM Adrian Hunter <adrian.hunter@intel.com> wrote: > >> > >> Add evlist__add_system_wide_dummy() to enable creating a system-wide dummy > >> event that sets up the system-wide maps before map propagation. > > > > Perhaps this should be: > > evlist__add_dummy_on_all_online_cpus() > > Ok, but offline isn't an option, so I'll drop 'online' from the name.
I'm not sure I follow. There can be CPUs that are offline (echo 0 > /sys/devices/system/cpu/cpu2/online) and then brought online while perf is running. The output obviously won't be right as we're missing dummy events. Losing online from the name here seems to remove a useful clue.
Thanks, Ian
> > my thoughts being that a system wide dummy sounds like the dummy CPU > > map, ie {-1} whilst what happens here is opening on all online CPUs > > {0-35} on a 36 hyperthread system. Note also that the libperf > > cpu_map__read_all_cpu_map code doesn't discover sysfs' mount properly, > > as done in: > > tools/lib/api/fs/fs.h > > Some tech debt. > > > >> For convenience, add evlist__add_aux_dummy() so that the logic can be used > >> whether or not the event needs to be system-wide. > >> > >> Signed-off-by: Adrian Hunter <adrian.hunter@intel.com> > >> --- > >> tools/perf/util/evlist.c | 40 ++++++++++++++++++++++++++++++++++++++++ > >> tools/perf/util/evlist.h | 5 +++++ > >> 2 files changed, 45 insertions(+) > >> > >> diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c > >> index 78c47cbafbc2..58ea562ddbd2 100644 > >> --- a/tools/perf/util/evlist.c > >> +++ b/tools/perf/util/evlist.c > >> @@ -264,6 +264,46 @@ int evlist__add_dummy(struct evlist *evlist) > >> return 0; > >> } > >> > >> +static void evlist__add_system_wide(struct evlist *evlist, struct evsel *evsel) > > > > This would be: > > evlist__add_on_all_online_cpus(..) > > > >> +{ > >> + evsel->core.system_wide = true; > >> + > >> + /* All CPUs */ > >> + perf_cpu_map__put(evsel->core.own_cpus); > >> + evsel->core.own_cpus = perf_cpu_map__new(NULL); > >> + perf_cpu_map__put(evsel->core.cpus); > >> + evsel->core.cpus = perf_cpu_map__get(evsel->core.own_cpus); > >> + > >> + /* No threads */ > >> + perf_thread_map__put(evsel->core.threads); > >> + evsel->core.threads = perf_thread_map__new_dummy(); > >> + > >> + evlist__add(evlist, evsel); > >> +} > >> + > >> +struct evsel *evlist__add_aux_dummy(struct evlist *evlist, bool system_wide) > >> +{ > >> + struct evsel *evsel = evlist__dummy_event(evlist); > >> + > >> + if (!evsel) > >> + return NULL; > >> + > >> + evsel->core.attr.exclude_kernel = 1; > >> + evsel->core.attr.exclude_guest = 1; > >> + evsel->core.attr.exclude_hv = 1; > >> + evsel->core.attr.freq = 0; > >> + evsel->core.attr.sample_period = 1; > >> + evsel->no_aux_samples = true; > >> + evsel->name = strdup("dummy:u"); > >> + > >> + if (system_wide) > >> + evlist__add_system_wide(evlist, evsel); > >> + else > >> + evlist__add(evlist, evsel); > >> + > >> + return evsel; > >> +} > >> + > >> static int evlist__add_attrs(struct evlist *evlist, struct perf_event_attr *attrs, size_t nr_attrs) > >> { > >> struct evsel *evsel, *n; > >> diff --git a/tools/perf/util/evlist.h b/tools/perf/util/evlist.h > >> index 4062f5aebfc1..dd1af114e033 100644 > >> --- a/tools/perf/util/evlist.h > >> +++ b/tools/perf/util/evlist.h > >> @@ -114,6 +114,11 @@ int arch_evlist__add_default_attrs(struct evlist *evlist); > >> struct evsel *arch_evlist__leader(struct list_head *list); > >> > >> int evlist__add_dummy(struct evlist *evlist); > >> +struct evsel *evlist__add_aux_dummy(struct evlist *evlist, bool system_wide); > >> +static inline struct evsel *evlist__add_system_wide_dummy(struct evlist *evlist) > >> +{ > >> + return evlist__add_aux_dummy(evlist, true); > >> +} > >> > >> int evlist__add_sb_event(struct evlist *evlist, struct perf_event_attr *attr, > >> evsel__sb_cb_t cb, void *data); > >> -- > >> 2.25.1 > >> >
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