Messages in this thread Patch in this message |  | | Date | Tue, 30 Jan 2018 14:39:17 +0100 | From | Jiri Olsa <> | Subject | Re: [PATCH V3 0/5] bugs fix for large PEBS mmap read and rdpmc read |
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On Tue, Jan 30, 2018 at 01:16:39AM -0800, Stephane Eranian wrote: > Hi, > > On Mon, Jan 29, 2018 at 8:29 AM, <kan.liang@linux.intel.com> wrote: > > > > From: Kan Liang <kan.liang@linux.intel.com> > > > > ------ > > > > Changes since V2: > > - Refined the changelog > > - Introduced specific read function for large PEBS. > > The previous generic PEBS read function is confusing. > > Disabled PMU in pmu::read() path for large PEBS. > > Handled the corner case when reload_times == 0. > > - Modified the parameter of intel_pmu_save_and_restart_reload() > > Discarded local64_cmpxchg > > - Added fixes tag > > - Added WARN to handle reload_times == 0 || reload_val == 0 > > > > Changes since V1: > > - Check PERF_X86_EVENT_AUTO_RELOAD before call > > intel_pmu_save_and_restore() > > It is not yet clear to me why PERF_SAMPLE_PERIOD is not allowed > with large PEBS. Large PEBS requires fixed period. So the kernel could > make up the period from the event and store it in the sampling buffer. > > I tried using large PEBS recently, and despite trying different option > combination of perf record, I was not able to get it to work. > > $ perf record -c 1 -e cpu/event=0xd1,umask=0x10,period=19936/pp > --no-timestamp --no-period -a -C 0 > > But I was able to make this work with a much older kernel. > > Another annoyance I ran into is with perf record requiring -c period > in order not to set > PERF_SAMPLE_PERIOD in the event. > > If I do: > perf record -c 1 -e cpu/event=0xd1,umask=0x10,period=19936/pp > --no-timestamp --no-period -a -C 0 > > I get > > perf_event_attr: > type 4 > size 112 > config 0x10d1 > { sample_period, sample_freq } 199936 > sample_type IP|TID|CPU > > But if I do: > perf record -e cpu/event=0xd1,umask=0x10,period=19936/pp > --no-timestamp --no-period -a -C 0 > > I get > > perf_event_attr: > type 4 > size 112 > config 0x10d1 > { sample_period, sample_freq } 199936 > sample_type IP|TID|CPU|PERIOD > > Perf should check if all events have a period=, then it should not > pass PERF_SAMPLE_PERIOD, even > more so when only one event is defined. > > Also it does not seem to honor --no-period.
yep, there's a bug in period=x term handling we did not re/set the sample_type based on that
attached patch fixes that for me, also takes into account the --no/-period options
jirka
--- diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c index f251e824edac..907267206973 100644 --- a/tools/perf/builtin-record.c +++ b/tools/perf/builtin-record.c @@ -1566,7 +1566,8 @@ static struct option __record_options[] = { OPT_BOOLEAN_SET('T', "timestamp", &record.opts.sample_time, &record.opts.sample_time_set, "Record the sample timestamps"), - OPT_BOOLEAN('P', "period", &record.opts.period, "Record the sample period"), + OPT_BOOLEAN_SET('P', "period", &record.opts.period, &record.opts.period_set, + "Record the sample period"), OPT_BOOLEAN('n', "no-samples", &record.opts.no_samples, "don't sample"), OPT_BOOLEAN_SET('N', "no-buildid-cache", &record.no_buildid_cache, diff --git a/tools/perf/perf.h b/tools/perf/perf.h index 2357f4ccc9c7..cfe46236a5e5 100644 --- a/tools/perf/perf.h +++ b/tools/perf/perf.h @@ -50,6 +50,7 @@ struct record_opts { bool sample_time_set; bool sample_cpu; bool period; + bool period_set; bool running_time; bool full_auxtrace; bool auxtrace_snapshot_mode; diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c index 66fa45198a11..ff359c9ece2e 100644 --- a/tools/perf/util/evsel.c +++ b/tools/perf/util/evsel.c @@ -745,12 +745,14 @@ static void apply_config_terms(struct perf_evsel *evsel, if (!(term->weak && opts->user_interval != ULLONG_MAX)) { attr->sample_period = term->val.period; attr->freq = 0; + perf_evsel__reset_sample_bit(evsel, PERIOD); } break; case PERF_EVSEL__CONFIG_TERM_FREQ: if (!(term->weak && opts->user_freq != UINT_MAX)) { attr->sample_freq = term->val.freq; attr->freq = 1; + perf_evsel__set_sample_bit(evsel, PERIOD); } break; case PERF_EVSEL__CONFIG_TERM_TIME: @@ -969,9 +971,6 @@ void perf_evsel__config(struct perf_evsel *evsel, struct record_opts *opts, if (target__has_cpu(&opts->target) || opts->sample_cpu) perf_evsel__set_sample_bit(evsel, CPU); - if (opts->period) - perf_evsel__set_sample_bit(evsel, PERIOD); - /* * When the user explicitly disabled time don't force it here. */ @@ -1073,6 +1072,14 @@ void perf_evsel__config(struct perf_evsel *evsel, struct record_opts *opts, apply_config_terms(evsel, opts, track); evsel->ignore_missing_thread = opts->ignore_missing_thread; + + /* The --period option takes the precedence. */ + if (opts->period_set) { + if (opts->period) + perf_evsel__set_sample_bit(evsel, PERIOD); + else + perf_evsel__reset_sample_bit(evsel, PERIOD); + } } static int perf_evsel__alloc_fd(struct perf_evsel *evsel, int ncpus, int nthreads)
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