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SubjectRe: [PATCH] perf: collect multiplexing timing information in perf record


On 08/26/2011 09:22 AM, Stephane Eranian wrote:
>
> This patch modifies perf record to collect multiplexing timing
> information (time_enabled, time_running) when the -R (raw) option
> is used.
>
> This allows you to compare events captured on a single run and
> compute multi-event metrics. Further it allows you to compare
> measurements between different runs where the number of collected
> events has changed and across different architectures where the
> event count will surely change.
>
> To normalize an event (assuming a fixed period), you do:
> total_events = n_samples * period * time_enabled / time_running
>
> You need the timing information to compensate for multiplexing
> which may have happened.
>
> To add timing information in each sample, it is necessary to
> set PERF_SAMPLE_READ as per the kernel API. That has the side
> effect of also storing the value of the sampling event in each
> sample. This patch modifies perf report to correctly parse
> such samples.
>
> Signed-off-by: Stephane Eranian <eranian@google.com>
>
> ---
> diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
> index 6b0519f..c54e580 100644
> --- a/tools/perf/builtin-record.c
> +++ b/tools/perf/builtin-record.c
> @@ -166,7 +166,7 @@ static void config_attr(struct perf_evsel *evsel, struct perf_evlist *evlist)
> PERF_FORMAT_TOTAL_TIME_RUNNING |
> PERF_FORMAT_ID;
>
> - attr->sample_type |= PERF_SAMPLE_IP | PERF_SAMPLE_TID;
> + attr->sample_type |= PERF_SAMPLE_IP | PERF_SAMPLE_TID;
>
> if (evlist->nr_entries > 1)
> attr->sample_type |= PERF_SAMPLE_ID;
> @@ -211,6 +211,7 @@ static void config_attr(struct perf_evsel *evsel, struct perf_evlist *evlist)
> attr->sample_type |= PERF_SAMPLE_TIME;
> attr->sample_type |= PERF_SAMPLE_RAW;
> attr->sample_type |= PERF_SAMPLE_CPU;
> + attr->sample_type |= PERF_SAMPLE_ID | PERF_SAMPLE_READ;
> }
>
> if (nodelay) {
> diff --git a/tools/perf/builtin-test.c b/tools/perf/builtin-test.c
> index 55f4c76..997b7d7 100644
> --- a/tools/perf/builtin-test.c
> +++ b/tools/perf/builtin-test.c
> @@ -561,7 +561,7 @@ static int test__basic_mmap(void)
> }
>
> err = perf_event__parse_sample(event, attr.sample_type, sample_size,
> - false, &sample);
> + false, 0, &sample);
> if (err) {
> pr_err("Can't parse sample, err = %d\n", err);
> goto out_munmap;
> diff --git a/tools/perf/util/event.h b/tools/perf/util/event.h
> index 1d7f664..ed193eb 100644
> --- a/tools/perf/util/event.h
> +++ b/tools/perf/util/event.h
> @@ -186,6 +186,6 @@ const char *perf_event__name(unsigned int id);
>
> int perf_event__parse_sample(const union perf_event *event, u64 type,
> int sample_size, bool sample_id_all,
> - struct perf_sample *sample);
> + u64 read_format, struct perf_sample *sample);
>
> #endif /* __PERF_RECORD_H */
> diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
> index c12bd47..be0e30c 100644
> --- a/tools/perf/util/evlist.c
> +++ b/tools/perf/util/evlist.c
> @@ -477,6 +477,14 @@ int perf_evlist__set_filters(struct perf_evlist *evlist)
> return 0;
> }
>
> +u64 perf_evlist__read_format(const struct perf_evlist *evlist)
> +{
> + struct perf_evsel *first;
> +
> + first = list_entry(evlist->entries.next, struct perf_evsel, node);
> + return first->attr.read_format;
> +}
> +
> bool perf_evlist__valid_sample_type(const struct perf_evlist *evlist)
> {
> struct perf_evsel *pos, *first;
> diff --git a/tools/perf/util/evlist.h b/tools/perf/util/evlist.h
> index ce85ae9..0c0d0ff 100644
> --- a/tools/perf/util/evlist.h
> +++ b/tools/perf/util/evlist.h
> @@ -68,6 +68,7 @@ int perf_evlist__create_maps(struct perf_evlist *evlist, pid_t target_pid,
> void perf_evlist__delete_maps(struct perf_evlist *evlist);
> int perf_evlist__set_filters(struct perf_evlist *evlist);
>
> +u64 perf_evlist__read_format(const struct perf_evlist *evlist);
> u64 perf_evlist__sample_type(const struct perf_evlist *evlist);
> bool perf_evlist__sample_id_all(const const struct perf_evlist *evlist);
>
> diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
> index a03a36b..630a7da 100644
> --- a/tools/perf/util/evsel.c
> +++ b/tools/perf/util/evsel.c
> @@ -340,9 +340,32 @@ static bool sample_overlap(const union perf_event *event,
> return false;
> }
>
> +static int
> +sample_read2u64(const u64 *array, u64 fmt)
> +{
> + u64 nr = 1;
> + int ret = 1; /* nr or value */
> +
> + if (fmt & PERF_FORMAT_TOTAL_TIME_ENABLED)
> + ret++;
> +
> + if (fmt & PERF_FORMAT_TOTAL_TIME_RUNNING)
> + ret++;
> +
> + if (fmt & PERF_FORMAT_GROUP) {
> + nr = *(u64 *)array;
> + ret += nr;
> + }
> +
> + if (fmt & PERF_FORMAT_ID)
> + ret += nr;

Why not add
struct read_format {
u64 value;
u64 time_enabled;
u64 time_running;
u64 id;
};

to perf_sample and save the data there?

David

> +
> + return ret;
> +}
> +
> int perf_event__parse_sample(const union perf_event *event, u64 type,
> int sample_size, bool sample_id_all,
> - struct perf_sample *data)
> + u64 read_format,struct perf_sample *data)
> {
> const u64 *array;
>
> @@ -405,10 +428,8 @@ int perf_event__parse_sample(const union perf_event *event, u64 type,
> array++;
> }
>
> - if (type & PERF_SAMPLE_READ) {
> - fprintf(stderr, "PERF_SAMPLE_READ is unsuported for now\n");
> - return -1;
> - }
> + if (type & PERF_SAMPLE_READ)
> + array += sample_read2u64(array, read_format);
>
> if (type & PERF_SAMPLE_CALLCHAIN) {
> if (sample_overlap(event, array, sizeof(data->callchain->nr)))
> diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
> index 72458d9..25a4cf9 100644
> --- a/tools/perf/util/session.c
> +++ b/tools/perf/util/session.c
> @@ -108,6 +108,7 @@ out:
> void perf_session__update_sample_type(struct perf_session *self)
> {
> self->sample_type = perf_evlist__sample_type(self->evlist);
> + self->read_format = perf_evlist__read_format(self->evlist);
> self->sample_size = __perf_evsel__sample_size(self->sample_type);
> self->sample_id_all = perf_evlist__sample_id_all(self->evlist);
> perf_session__id_header_size(self);
> diff --git a/tools/perf/util/session.h b/tools/perf/util/session.h
> index 170601e..903fc1a 100644
> --- a/tools/perf/util/session.h
> +++ b/tools/perf/util/session.h
> @@ -42,7 +42,8 @@ struct perf_session {
> * perf.data file.
> */
> struct hists hists;
> - u64 sample_type;
> + u64 sample_type; /* identical for all events */
> + u64 read_format; /* identical for all events */
> int sample_size;
> int fd;
> bool fd_pipe;
> @@ -162,7 +163,9 @@ static inline int perf_session__parse_sample(struct perf_session *session,
> {
> return perf_event__parse_sample(event, session->sample_type,
> session->sample_size,
> - session->sample_id_all, sample);
> + session->sample_id_all,
> + session->read_format,
> + sample);
> }
>
> struct perf_evsel *perf_session__find_first_evtype(struct perf_session *session,
> --
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