Messages in this thread | | | Date | Thu, 1 Sep 2022 14:22:45 +0300 | Subject | Re: [PATCH 3/5] perf record: Read and inject LOST_SAMPLES events | From | Adrian Hunter <> |
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On 1/09/22 00:03, Namhyung Kim wrote: > When there are lost samples, it can read the number of PERF_FORMAT_LOST and > convert it to PERF_RECORD_LOST_SAMPLES and write to the data file at the end. > > Signed-off-by: Namhyung Kim <namhyung@kernel.org> > --- > tools/perf/builtin-record.c | 60 +++++++++++++++++++++++++++++++++++++ > 1 file changed, 60 insertions(+) > > diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c > index bce8c941d558..cb9881543a07 100644 > --- a/tools/perf/builtin-record.c > +++ b/tools/perf/builtin-record.c > @@ -10,6 +10,7 @@ > > #include "util/build-id.h" > #include <subcmd/parse-options.h> > +#include <internal/xyarray.h> > #include "util/parse-events.h" > #include "util/config.h" > > @@ -1852,6 +1853,64 @@ record__switch_output(struct record *rec, bool at_exit) > return fd; > } > > +static void __record__read_lost_samples(struct record *rec, struct evsel *evsel, > + struct perf_record_lost_samples *lost, > + int size, int cpu_idx, int thread_idx) > +{ > + struct perf_counts_values count; > + struct perf_sample_id *sid; > + struct perf_sample sample = {}; > + > + if (perf_evsel__read(&evsel->core, cpu_idx, thread_idx, &count) < 0) { > + pr_err("read LOST count failed\n"); > + return; > + } > + > + if (count.lost == 0) > + return; > + > + lost->lost = count.lost; > + if (evsel->core.ids) { > + sid = xyarray__entry(evsel->core.sample_id, cpu_idx, thread_idx); > + sample.id = sid->id; > + } > + > + perf_event__synthesize_id_sample((void *)(lost + 1), > + evsel->core.attr.sample_type, &sample);
The ID sample size can vary with sample_type and is not necessarily the same as machine->id_hdr_size.
The following might be more robust:
id_hdr_size = perf_event__synthesize_id_sample((void *)(lost + 1), evsel->core.attr.sample_type, &sample); lost->header.size = sizeof(*lost) + id_hdr_size;
> + record__write(rec, NULL, lost, size); > +} > + > +static void record__read_lost_samples(struct record *rec) > +{ > + struct perf_session *session = rec->session; > + struct machine *machine = &session->machines.host; > + struct perf_record_lost_samples *lost; > + struct evsel *evsel; > + int size = sizeof(*lost) + machine->id_hdr_size;
- int size = sizeof(*lost) + machine->id_hdr_size;
> + > + lost = zalloc(size);
lost = zalloc(PERF_SAMPLE_MAX_SIZE);
> + lost->header.type = PERF_RECORD_LOST_SAMPLES; > + lost->header.size = size;
- lost->header.size = size;
> + > + evlist__for_each_entry(session->evlist, evsel) { > + struct xyarray *xy = evsel->core.sample_id; > + > + if (xyarray__max_x(evsel->core.fd) != xyarray__max_x(xy) || > + xyarray__max_y(evsel->core.fd) != xyarray__max_y(xy)) { > + pr_debug("Unmatched FD vs. sample ID: skip reading LOST count\n"); > + continue; > + } > + > + for (int x = 0; x < xyarray__max_x(xy); x++) { > + for (int y = 0; y < xyarray__max_y(xy); y++) { > + __record__read_lost_samples(rec, evsel, lost, > + size, x, y); > + } > + } > + } > + > +} > + > static volatile int workload_exec_errno; > > /* > @@ -2710,6 +2769,7 @@ static int __cmd_record(struct record *rec, int argc, const char **argv) > if (rec->off_cpu) > rec->bytes_written += off_cpu_write(rec->session); > > + record__read_lost_samples(rec); > record__synthesize(rec, true); > /* this will be recalculated during process_buildids() */ > rec->samples = 0;
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