Messages in this thread | | | Subject | Re: [PATCH v1 2/3] perf arm-spe: Correct sample flags for dummy event | From | James Clark <> | Date | Wed, 12 May 2021 17:39:56 +0300 |
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On 29/04/2021 18:00, Leo Yan wrote: > The dummy event is mainly used for mmap, the TIME sample is only needed > for per-cpu case so that the perf tool can rely on the correct timing > for parsing symbols. And the CPU sample is useless for mmap. > > This patch enables TIME sample for per-cpu mmap and doesn't enable CPU > sample. For later extension (e.g. support multiple AUX events), it sets > the dummy event when the condition "opts->full_auxtrace" is true. > > Signed-off-by: Leo Yan <leo.yan@linaro.org> > --- > tools/perf/arch/arm64/util/arm-spe.c | 30 ++++++++++++++++------------ > 1 file changed, 17 insertions(+), 13 deletions(-) > > diff --git a/tools/perf/arch/arm64/util/arm-spe.c b/tools/perf/arch/arm64/util/arm-spe.c > index 902e73a64184..f6eec0900604 100644 > --- a/tools/perf/arch/arm64/util/arm-spe.c > +++ b/tools/perf/arch/arm64/util/arm-spe.c > @@ -70,7 +70,6 @@ static int arm_spe_recording_options(struct auxtrace_record *itr, > struct evsel *evsel, *arm_spe_evsel = NULL; > struct perf_cpu_map *cpus = evlist->core.cpus; > bool privileged = perf_event_paranoid_check(-1); > - struct evsel *tracking_evsel; > int err; > > sper->evlist = evlist; > @@ -126,18 +125,23 @@ static int arm_spe_recording_options(struct auxtrace_record *itr, > evsel__set_sample_bit(arm_spe_evsel, CPU); > > /* Add dummy event to keep tracking */ > - err = parse_events(evlist, "dummy:u", NULL); > - if (err) > - return err; > - > - tracking_evsel = evlist__last(evlist); > - evlist__set_tracking_event(evlist, tracking_evsel); > - > - tracking_evsel->core.attr.freq = 0; > - tracking_evsel->core.attr.sample_period = 1; > - evsel__set_sample_bit(tracking_evsel, TIME); > - evsel__set_sample_bit(tracking_evsel, CPU); > - evsel__reset_sample_bit(tracking_evsel, BRANCH_STACK); > + if (opts->full_auxtrace) { > + struct evsel *tracking_evsel;
Hi Leo,
I know the "if (opts->full_auxtrace)" pattern is copied from other auxtrace files, but I don't think it does anything because there is this at the top of the function:
if (!opts->full_auxtrace) return 0;
The same applies for other usages of "full_auxtrace" in the same function. They are all always true. I'm also not sure if it's ever defined what full_auxtrace means.
James
> + > + err = parse_events(evlist, "dummy:u", NULL); > + if (err) > + return err; > + > + tracking_evsel = evlist__last(evlist); > + evlist__set_tracking_event(evlist, tracking_evsel); > + > + tracking_evsel->core.attr.freq = 0; > + tracking_evsel->core.attr.sample_period = 1; > + > + /* In per-cpu case, always need the time of mmap events etc */ > + if (!perf_cpu_map__empty(cpus)) > + evsel__set_sample_bit(tracking_evsel, TIME); > + } > > return 0; > } >
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