* [PATCH v2] perf metric: Reduce multiplexing with duration_time
@ 2021-11-24 1:52 Ian Rogers
2021-11-28 16:23 ` Jiri Olsa
0 siblings, 1 reply; 5+ messages in thread
From: Ian Rogers @ 2021-11-24 1:52 UTC (permalink / raw)
To: Andi Kleen, Jiri Olsa, Namhyung Kim, John Garry, Kajol Jain,
Paul A . Clarke, Arnaldo Carvalho de Melo, Kan Liang,
Peter Zijlstra, Ingo Molnar, Mark Rutland, Alexander Shishkin,
linux-perf-users, linux-kernel
Cc: eranian, Ian Rogers
It is common to use the same counters with and without
duration_time. The ID sharing code treats duration_time as if it
were a hardware event placed in the same group. This causes
unnecessary multiplexing such as in the following example where
l3_cache_access isn't shared:
$ perf stat -M l3 -a sleep 1
Performance counter stats for 'system wide':
3,117,007 l3_cache_miss # 199.5 MB/s l3_rd_bw
# 43.6 % l3_hits
# 56.4 % l3_miss (50.00%)
5,526,447 l3_cache_access (50.00%)
5,392,435 l3_cache_access # 5389191.2 access/s l3_access_rate (50.00%)
1,000,601,901 ns duration_time
1.000601901 seconds time elapsed
Fix this by placing duration_time in all groups unless metric
sharing has been disabled on the command line:
$ perf stat -M l3 -a sleep 1
Performance counter stats for 'system wide':
3,597,972 l3_cache_miss # 230.3 MB/s l3_rd_bw
# 48.0 % l3_hits
# 52.0 % l3_miss
6,914,459 l3_cache_access # 6909935.9 access/s l3_access_rate
1,000,654,579 ns duration_time
1.000654579 seconds time elapsed
$ perf stat --metric-no-merge -M l3 -a sleep 1
Performance counter stats for 'system wide':
3,501,834 l3_cache_miss # 53.5 % l3_miss (24.99%)
6,548,173 l3_cache_access (24.99%)
3,417,622 l3_cache_miss # 45.7 % l3_hits (25.04%)
6,294,062 l3_cache_access (25.04%)
5,923,238 l3_cache_access # 5919688.1 access/s l3_access_rate (24.99%)
1,000,599,683 ns duration_time
3,607,486 l3_cache_miss # 230.9 MB/s l3_rd_bw (49.97%)
1.000599683 seconds time elapsed
v2. Doesn't count duration_time in the metric_list_cmp function that
sorts larger metrics first. Without this a metric with duration_time
and an event is sorted the same as a metric with two events,
possibly not allowing the first metric to share with the second.
Signed-off-by: Ian Rogers <irogers@google.com>
---
tools/perf/util/metricgroup.c | 42 +++++++++++++++++++++++++++--------
1 file changed, 33 insertions(+), 9 deletions(-)
diff --git a/tools/perf/util/metricgroup.c b/tools/perf/util/metricgroup.c
index fffe02aae3ed..51c99cb08abf 100644
--- a/tools/perf/util/metricgroup.c
+++ b/tools/perf/util/metricgroup.c
@@ -1115,13 +1115,27 @@ static int metricgroup__add_metric_sys_event_iter(const struct pmu_event *pe,
return ret;
}
+/**
+ * metric_list_cmp - list_sort comparator that sorts metrics with more events to
+ * the front. duration_time is excluded from the count.
+ */
static int metric_list_cmp(void *priv __maybe_unused, const struct list_head *l,
const struct list_head *r)
{
const struct metric *left = container_of(l, struct metric, nd);
const struct metric *right = container_of(r, struct metric, nd);
+ struct expr_id_data *data;
+ int left_count, right_count;
+
+ left_count = hashmap__size(left->pctx->ids);
+ if (!expr__get_id(left->pctx, "duration_time", &data))
+ left_count--;
+
+ right_count = hashmap__size(right->pctx->ids);
+ if (!expr__get_id(right->pctx, "duration_time", &data))
+ right_count--;
- return hashmap__size(right->pctx->ids) - hashmap__size(left->pctx->ids);
+ return right_count - left_count;
}
/**
@@ -1299,14 +1313,16 @@ static int build_combined_expr_ctx(const struct list_head *metric_list,
/**
* parse_ids - Build the event string for the ids and parse them creating an
* evlist. The encoded metric_ids are decoded.
+ * @metric_no_merge: is metric sharing explicitly disabled.
* @fake_pmu: used when testing metrics not supported by the current CPU.
* @ids: the event identifiers parsed from a metric.
* @modifier: any modifiers added to the events.
* @has_constraint: false if events should be placed in a weak group.
* @out_evlist: the created list of events.
*/
-static int parse_ids(struct perf_pmu *fake_pmu, struct expr_parse_ctx *ids,
- const char *modifier, bool has_constraint, struct evlist **out_evlist)
+static int parse_ids(bool metric_no_merge, struct perf_pmu *fake_pmu,
+ struct expr_parse_ctx *ids, const char *modifier,
+ bool has_constraint, struct evlist **out_evlist)
{
struct parse_events_error parse_error;
struct evlist *parsed_evlist;
@@ -1314,12 +1330,19 @@ static int parse_ids(struct perf_pmu *fake_pmu, struct expr_parse_ctx *ids,
int ret;
*out_evlist = NULL;
- if (hashmap__size(ids->ids) == 0) {
+ if (!metric_no_merge || hashmap__size(ids->ids) == 0) {
char *tmp;
/*
- * No ids/events in the expression parsing context. Events may
- * have been removed because of constant evaluation, e.g.:
- * event1 if #smt_on else 0
+ * We may fail to share events between metrics because
+ * duration_time isn't present in one metric. For example, a
+ * ratio of cache misses doesn't need duration_time but the same
+ * events may be used for a misses per second. Events without
+ * sharing implies multiplexing, that is best avoided, so place
+ * duration_time in every group.
+ *
+ * Also, there may be no ids/events in the expression parsing
+ * context because of constant evaluation, e.g.:
+ * event1 if #smt_on else 0
* Add a duration_time event to avoid a parse error on an empty
* string.
*/
@@ -1387,7 +1410,8 @@ static int parse_groups(struct evlist *perf_evlist, const char *str,
ret = build_combined_expr_ctx(&metric_list, &combined);
if (!ret && combined && hashmap__size(combined->ids)) {
- ret = parse_ids(fake_pmu, combined, /*modifier=*/NULL,
+ ret = parse_ids(metric_no_merge, fake_pmu, combined,
+ /*modifier=*/NULL,
/*has_constraint=*/true,
&combined_evlist);
}
@@ -1435,7 +1459,7 @@ static int parse_groups(struct evlist *perf_evlist, const char *str,
}
}
if (!metric_evlist) {
- ret = parse_ids(fake_pmu, m->pctx, m->modifier,
+ ret = parse_ids(metric_no_merge, fake_pmu, m->pctx, m->modifier,
m->has_constraint, &m->evlist);
if (ret)
goto out;
--
2.34.0.rc2.393.gf8c9666880-goog
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH v2] perf metric: Reduce multiplexing with duration_time
2021-11-24 1:52 [PATCH v2] perf metric: Reduce multiplexing with duration_time Ian Rogers
@ 2021-11-28 16:23 ` Jiri Olsa
2021-11-29 17:46 ` Ian Rogers
0 siblings, 1 reply; 5+ messages in thread
From: Jiri Olsa @ 2021-11-28 16:23 UTC (permalink / raw)
To: Ian Rogers
Cc: Andi Kleen, Namhyung Kim, John Garry, Kajol Jain, Paul A . Clarke,
Arnaldo Carvalho de Melo, Kan Liang, Peter Zijlstra, Ingo Molnar,
Mark Rutland, Alexander Shishkin, linux-perf-users, linux-kernel,
eranian
On Tue, Nov 23, 2021 at 05:52:26PM -0800, Ian Rogers wrote:
> It is common to use the same counters with and without
> duration_time. The ID sharing code treats duration_time as if it
> were a hardware event placed in the same group. This causes
> unnecessary multiplexing such as in the following example where
> l3_cache_access isn't shared:
>
> $ perf stat -M l3 -a sleep 1
>
> Performance counter stats for 'system wide':
>
> 3,117,007 l3_cache_miss # 199.5 MB/s l3_rd_bw
> # 43.6 % l3_hits
> # 56.4 % l3_miss (50.00%)
> 5,526,447 l3_cache_access (50.00%)
> 5,392,435 l3_cache_access # 5389191.2 access/s l3_access_rate (50.00%)
> 1,000,601,901 ns duration_time
>
> 1.000601901 seconds time elapsed
>
> Fix this by placing duration_time in all groups unless metric
> sharing has been disabled on the command line:
>
> $ perf stat -M l3 -a sleep 1
>
> Performance counter stats for 'system wide':
>
> 3,597,972 l3_cache_miss # 230.3 MB/s l3_rd_bw
> # 48.0 % l3_hits
> # 52.0 % l3_miss
> 6,914,459 l3_cache_access # 6909935.9 access/s l3_access_rate
> 1,000,654,579 ns duration_time
>
> 1.000654579 seconds time elapsed
>
> $ perf stat --metric-no-merge -M l3 -a sleep 1
>
> Performance counter stats for 'system wide':
>
> 3,501,834 l3_cache_miss # 53.5 % l3_miss (24.99%)
> 6,548,173 l3_cache_access (24.99%)
> 3,417,622 l3_cache_miss # 45.7 % l3_hits (25.04%)
> 6,294,062 l3_cache_access (25.04%)
> 5,923,238 l3_cache_access # 5919688.1 access/s l3_access_rate (24.99%)
> 1,000,599,683 ns duration_time
> 3,607,486 l3_cache_miss # 230.9 MB/s l3_rd_bw (49.97%)
>
> 1.000599683 seconds time elapsed
>
> v2. Doesn't count duration_time in the metric_list_cmp function that
> sorts larger metrics first. Without this a metric with duration_time
> and an event is sorted the same as a metric with two events,
> possibly not allowing the first metric to share with the second.
hum, isn't the change about adding duration_time in every metric?
or you could still end up with metric without duration_time
thanks,
jirka
>
> Signed-off-by: Ian Rogers <irogers@google.com>
> ---
> tools/perf/util/metricgroup.c | 42 +++++++++++++++++++++++++++--------
> 1 file changed, 33 insertions(+), 9 deletions(-)
>
> diff --git a/tools/perf/util/metricgroup.c b/tools/perf/util/metricgroup.c
> index fffe02aae3ed..51c99cb08abf 100644
> --- a/tools/perf/util/metricgroup.c
> +++ b/tools/perf/util/metricgroup.c
> @@ -1115,13 +1115,27 @@ static int metricgroup__add_metric_sys_event_iter(const struct pmu_event *pe,
> return ret;
> }
>
> +/**
> + * metric_list_cmp - list_sort comparator that sorts metrics with more events to
> + * the front. duration_time is excluded from the count.
> + */
> static int metric_list_cmp(void *priv __maybe_unused, const struct list_head *l,
> const struct list_head *r)
> {
> const struct metric *left = container_of(l, struct metric, nd);
> const struct metric *right = container_of(r, struct metric, nd);
> + struct expr_id_data *data;
> + int left_count, right_count;
> +
> + left_count = hashmap__size(left->pctx->ids);
> + if (!expr__get_id(left->pctx, "duration_time", &data))
> + left_count--;
> +
> + right_count = hashmap__size(right->pctx->ids);
> + if (!expr__get_id(right->pctx, "duration_time", &data))
> + right_count--;
>
> - return hashmap__size(right->pctx->ids) - hashmap__size(left->pctx->ids);
> + return right_count - left_count;
> }
>
> /**
> @@ -1299,14 +1313,16 @@ static int build_combined_expr_ctx(const struct list_head *metric_list,
> /**
> * parse_ids - Build the event string for the ids and parse them creating an
> * evlist. The encoded metric_ids are decoded.
> + * @metric_no_merge: is metric sharing explicitly disabled.
> * @fake_pmu: used when testing metrics not supported by the current CPU.
> * @ids: the event identifiers parsed from a metric.
> * @modifier: any modifiers added to the events.
> * @has_constraint: false if events should be placed in a weak group.
> * @out_evlist: the created list of events.
> */
> -static int parse_ids(struct perf_pmu *fake_pmu, struct expr_parse_ctx *ids,
> - const char *modifier, bool has_constraint, struct evlist **out_evlist)
> +static int parse_ids(bool metric_no_merge, struct perf_pmu *fake_pmu,
> + struct expr_parse_ctx *ids, const char *modifier,
> + bool has_constraint, struct evlist **out_evlist)
> {
> struct parse_events_error parse_error;
> struct evlist *parsed_evlist;
> @@ -1314,12 +1330,19 @@ static int parse_ids(struct perf_pmu *fake_pmu, struct expr_parse_ctx *ids,
> int ret;
>
> *out_evlist = NULL;
> - if (hashmap__size(ids->ids) == 0) {
> + if (!metric_no_merge || hashmap__size(ids->ids) == 0) {
> char *tmp;
> /*
> - * No ids/events in the expression parsing context. Events may
> - * have been removed because of constant evaluation, e.g.:
> - * event1 if #smt_on else 0
> + * We may fail to share events between metrics because
> + * duration_time isn't present in one metric. For example, a
> + * ratio of cache misses doesn't need duration_time but the same
> + * events may be used for a misses per second. Events without
> + * sharing implies multiplexing, that is best avoided, so place
> + * duration_time in every group.
> + *
> + * Also, there may be no ids/events in the expression parsing
> + * context because of constant evaluation, e.g.:
> + * event1 if #smt_on else 0
> * Add a duration_time event to avoid a parse error on an empty
> * string.
> */
> @@ -1387,7 +1410,8 @@ static int parse_groups(struct evlist *perf_evlist, const char *str,
> ret = build_combined_expr_ctx(&metric_list, &combined);
>
> if (!ret && combined && hashmap__size(combined->ids)) {
> - ret = parse_ids(fake_pmu, combined, /*modifier=*/NULL,
> + ret = parse_ids(metric_no_merge, fake_pmu, combined,
> + /*modifier=*/NULL,
> /*has_constraint=*/true,
> &combined_evlist);
> }
> @@ -1435,7 +1459,7 @@ static int parse_groups(struct evlist *perf_evlist, const char *str,
> }
> }
> if (!metric_evlist) {
> - ret = parse_ids(fake_pmu, m->pctx, m->modifier,
> + ret = parse_ids(metric_no_merge, fake_pmu, m->pctx, m->modifier,
> m->has_constraint, &m->evlist);
> if (ret)
> goto out;
> --
> 2.34.0.rc2.393.gf8c9666880-goog
>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH v2] perf metric: Reduce multiplexing with duration_time
2021-11-28 16:23 ` Jiri Olsa
@ 2021-11-29 17:46 ` Ian Rogers
2021-11-30 18:11 ` Jiri Olsa
0 siblings, 1 reply; 5+ messages in thread
From: Ian Rogers @ 2021-11-29 17:46 UTC (permalink / raw)
To: Jiri Olsa
Cc: Andi Kleen, Namhyung Kim, John Garry, Kajol Jain, Paul A . Clarke,
Arnaldo Carvalho de Melo, Kan Liang, Peter Zijlstra, Ingo Molnar,
Mark Rutland, Alexander Shishkin, linux-perf-users, linux-kernel,
eranian
On Sun, Nov 28, 2021 at 8:23 AM Jiri Olsa <jolsa@redhat.com> wrote:
>
> On Tue, Nov 23, 2021 at 05:52:26PM -0800, Ian Rogers wrote:
> > It is common to use the same counters with and without
> > duration_time. The ID sharing code treats duration_time as if it
> > were a hardware event placed in the same group. This causes
> > unnecessary multiplexing such as in the following example where
> > l3_cache_access isn't shared:
> >
> > $ perf stat -M l3 -a sleep 1
> >
> > Performance counter stats for 'system wide':
> >
> > 3,117,007 l3_cache_miss # 199.5 MB/s l3_rd_bw
> > # 43.6 % l3_hits
> > # 56.4 % l3_miss (50.00%)
> > 5,526,447 l3_cache_access (50.00%)
> > 5,392,435 l3_cache_access # 5389191.2 access/s l3_access_rate (50.00%)
> > 1,000,601,901 ns duration_time
> >
> > 1.000601901 seconds time elapsed
> >
> > Fix this by placing duration_time in all groups unless metric
> > sharing has been disabled on the command line:
> >
> > $ perf stat -M l3 -a sleep 1
> >
> > Performance counter stats for 'system wide':
> >
> > 3,597,972 l3_cache_miss # 230.3 MB/s l3_rd_bw
> > # 48.0 % l3_hits
> > # 52.0 % l3_miss
> > 6,914,459 l3_cache_access # 6909935.9 access/s l3_access_rate
> > 1,000,654,579 ns duration_time
> >
> > 1.000654579 seconds time elapsed
> >
> > $ perf stat --metric-no-merge -M l3 -a sleep 1
> >
> > Performance counter stats for 'system wide':
> >
> > 3,501,834 l3_cache_miss # 53.5 % l3_miss (24.99%)
> > 6,548,173 l3_cache_access (24.99%)
> > 3,417,622 l3_cache_miss # 45.7 % l3_hits (25.04%)
> > 6,294,062 l3_cache_access (25.04%)
> > 5,923,238 l3_cache_access # 5919688.1 access/s l3_access_rate (24.99%)
> > 1,000,599,683 ns duration_time
> > 3,607,486 l3_cache_miss # 230.9 MB/s l3_rd_bw (49.97%)
> >
> > 1.000599683 seconds time elapsed
> >
> > v2. Doesn't count duration_time in the metric_list_cmp function that
> > sorts larger metrics first. Without this a metric with duration_time
> > and an event is sorted the same as a metric with two events,
> > possibly not allowing the first metric to share with the second.
>
> hum, isn't the change about adding duration_time in every metric?
> or you could still end up with metric without duration_time
It is about adding duration_time to all metrics. Sorting of the
metrics by number of IDs happens before we insert duration_time which
happens just prior to parsing. duration_time needn't be inserted if
--metric-no-merge is passed.
Thanks,
Ian
> thanks,
> jirka
>
> >
> > Signed-off-by: Ian Rogers <irogers@google.com>
> > ---
> > tools/perf/util/metricgroup.c | 42 +++++++++++++++++++++++++++--------
> > 1 file changed, 33 insertions(+), 9 deletions(-)
> >
> > diff --git a/tools/perf/util/metricgroup.c b/tools/perf/util/metricgroup.c
> > index fffe02aae3ed..51c99cb08abf 100644
> > --- a/tools/perf/util/metricgroup.c
> > +++ b/tools/perf/util/metricgroup.c
> > @@ -1115,13 +1115,27 @@ static int metricgroup__add_metric_sys_event_iter(const struct pmu_event *pe,
> > return ret;
> > }
> >
> > +/**
> > + * metric_list_cmp - list_sort comparator that sorts metrics with more events to
> > + * the front. duration_time is excluded from the count.
> > + */
> > static int metric_list_cmp(void *priv __maybe_unused, const struct list_head *l,
> > const struct list_head *r)
> > {
> > const struct metric *left = container_of(l, struct metric, nd);
> > const struct metric *right = container_of(r, struct metric, nd);
> > + struct expr_id_data *data;
> > + int left_count, right_count;
> > +
> > + left_count = hashmap__size(left->pctx->ids);
> > + if (!expr__get_id(left->pctx, "duration_time", &data))
> > + left_count--;
> > +
> > + right_count = hashmap__size(right->pctx->ids);
> > + if (!expr__get_id(right->pctx, "duration_time", &data))
> > + right_count--;
> >
> > - return hashmap__size(right->pctx->ids) - hashmap__size(left->pctx->ids);
> > + return right_count - left_count;
> > }
> >
> > /**
> > @@ -1299,14 +1313,16 @@ static int build_combined_expr_ctx(const struct list_head *metric_list,
> > /**
> > * parse_ids - Build the event string for the ids and parse them creating an
> > * evlist. The encoded metric_ids are decoded.
> > + * @metric_no_merge: is metric sharing explicitly disabled.
> > * @fake_pmu: used when testing metrics not supported by the current CPU.
> > * @ids: the event identifiers parsed from a metric.
> > * @modifier: any modifiers added to the events.
> > * @has_constraint: false if events should be placed in a weak group.
> > * @out_evlist: the created list of events.
> > */
> > -static int parse_ids(struct perf_pmu *fake_pmu, struct expr_parse_ctx *ids,
> > - const char *modifier, bool has_constraint, struct evlist **out_evlist)
> > +static int parse_ids(bool metric_no_merge, struct perf_pmu *fake_pmu,
> > + struct expr_parse_ctx *ids, const char *modifier,
> > + bool has_constraint, struct evlist **out_evlist)
> > {
> > struct parse_events_error parse_error;
> > struct evlist *parsed_evlist;
> > @@ -1314,12 +1330,19 @@ static int parse_ids(struct perf_pmu *fake_pmu, struct expr_parse_ctx *ids,
> > int ret;
> >
> > *out_evlist = NULL;
> > - if (hashmap__size(ids->ids) == 0) {
> > + if (!metric_no_merge || hashmap__size(ids->ids) == 0) {
> > char *tmp;
> > /*
> > - * No ids/events in the expression parsing context. Events may
> > - * have been removed because of constant evaluation, e.g.:
> > - * event1 if #smt_on else 0
> > + * We may fail to share events between metrics because
> > + * duration_time isn't present in one metric. For example, a
> > + * ratio of cache misses doesn't need duration_time but the same
> > + * events may be used for a misses per second. Events without
> > + * sharing implies multiplexing, that is best avoided, so place
> > + * duration_time in every group.
> > + *
> > + * Also, there may be no ids/events in the expression parsing
> > + * context because of constant evaluation, e.g.:
> > + * event1 if #smt_on else 0
> > * Add a duration_time event to avoid a parse error on an empty
> > * string.
> > */
> > @@ -1387,7 +1410,8 @@ static int parse_groups(struct evlist *perf_evlist, const char *str,
> > ret = build_combined_expr_ctx(&metric_list, &combined);
> >
> > if (!ret && combined && hashmap__size(combined->ids)) {
> > - ret = parse_ids(fake_pmu, combined, /*modifier=*/NULL,
> > + ret = parse_ids(metric_no_merge, fake_pmu, combined,
> > + /*modifier=*/NULL,
> > /*has_constraint=*/true,
> > &combined_evlist);
> > }
> > @@ -1435,7 +1459,7 @@ static int parse_groups(struct evlist *perf_evlist, const char *str,
> > }
> > }
> > if (!metric_evlist) {
> > - ret = parse_ids(fake_pmu, m->pctx, m->modifier,
> > + ret = parse_ids(metric_no_merge, fake_pmu, m->pctx, m->modifier,
> > m->has_constraint, &m->evlist);
> > if (ret)
> > goto out;
> > --
> > 2.34.0.rc2.393.gf8c9666880-goog
> >
>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH v2] perf metric: Reduce multiplexing with duration_time
2021-11-29 17:46 ` Ian Rogers
@ 2021-11-30 18:11 ` Jiri Olsa
2021-11-30 19:24 ` Arnaldo Carvalho de Melo
0 siblings, 1 reply; 5+ messages in thread
From: Jiri Olsa @ 2021-11-30 18:11 UTC (permalink / raw)
To: Ian Rogers
Cc: Andi Kleen, Namhyung Kim, John Garry, Kajol Jain, Paul A . Clarke,
Arnaldo Carvalho de Melo, Kan Liang, Peter Zijlstra, Ingo Molnar,
Mark Rutland, Alexander Shishkin, linux-perf-users, linux-kernel,
eranian
On Mon, Nov 29, 2021 at 09:46:31AM -0800, Ian Rogers wrote:
> On Sun, Nov 28, 2021 at 8:23 AM Jiri Olsa <jolsa@redhat.com> wrote:
> >
> > On Tue, Nov 23, 2021 at 05:52:26PM -0800, Ian Rogers wrote:
> > > It is common to use the same counters with and without
> > > duration_time. The ID sharing code treats duration_time as if it
> > > were a hardware event placed in the same group. This causes
> > > unnecessary multiplexing such as in the following example where
> > > l3_cache_access isn't shared:
> > >
> > > $ perf stat -M l3 -a sleep 1
> > >
> > > Performance counter stats for 'system wide':
> > >
> > > 3,117,007 l3_cache_miss # 199.5 MB/s l3_rd_bw
> > > # 43.6 % l3_hits
> > > # 56.4 % l3_miss (50.00%)
> > > 5,526,447 l3_cache_access (50.00%)
> > > 5,392,435 l3_cache_access # 5389191.2 access/s l3_access_rate (50.00%)
> > > 1,000,601,901 ns duration_time
> > >
> > > 1.000601901 seconds time elapsed
> > >
> > > Fix this by placing duration_time in all groups unless metric
> > > sharing has been disabled on the command line:
> > >
> > > $ perf stat -M l3 -a sleep 1
> > >
> > > Performance counter stats for 'system wide':
> > >
> > > 3,597,972 l3_cache_miss # 230.3 MB/s l3_rd_bw
> > > # 48.0 % l3_hits
> > > # 52.0 % l3_miss
> > > 6,914,459 l3_cache_access # 6909935.9 access/s l3_access_rate
> > > 1,000,654,579 ns duration_time
> > >
> > > 1.000654579 seconds time elapsed
> > >
> > > $ perf stat --metric-no-merge -M l3 -a sleep 1
> > >
> > > Performance counter stats for 'system wide':
> > >
> > > 3,501,834 l3_cache_miss # 53.5 % l3_miss (24.99%)
> > > 6,548,173 l3_cache_access (24.99%)
> > > 3,417,622 l3_cache_miss # 45.7 % l3_hits (25.04%)
> > > 6,294,062 l3_cache_access (25.04%)
> > > 5,923,238 l3_cache_access # 5919688.1 access/s l3_access_rate (24.99%)
> > > 1,000,599,683 ns duration_time
> > > 3,607,486 l3_cache_miss # 230.9 MB/s l3_rd_bw (49.97%)
> > >
> > > 1.000599683 seconds time elapsed
> > >
> > > v2. Doesn't count duration_time in the metric_list_cmp function that
> > > sorts larger metrics first. Without this a metric with duration_time
> > > and an event is sorted the same as a metric with two events,
> > > possibly not allowing the first metric to share with the second.
> >
> > hum, isn't the change about adding duration_time in every metric?
> > or you could still end up with metric without duration_time
>
> It is about adding duration_time to all metrics. Sorting of the
> metrics by number of IDs happens before we insert duration_time which
> happens just prior to parsing. duration_time needn't be inserted if
> --metric-no-merge is passed.
I see, so that sorting takes place before it's added, makes sense then
Acked-by: Jiri Olsa <jolsa@redhat.com>
thanks,
jirka
>
> Thanks,
> Ian
>
> > thanks,
> > jirka
> >
> > >
> > > Signed-off-by: Ian Rogers <irogers@google.com>
> > > ---
> > > tools/perf/util/metricgroup.c | 42 +++++++++++++++++++++++++++--------
> > > 1 file changed, 33 insertions(+), 9 deletions(-)
> > >
> > > diff --git a/tools/perf/util/metricgroup.c b/tools/perf/util/metricgroup.c
> > > index fffe02aae3ed..51c99cb08abf 100644
> > > --- a/tools/perf/util/metricgroup.c
> > > +++ b/tools/perf/util/metricgroup.c
> > > @@ -1115,13 +1115,27 @@ static int metricgroup__add_metric_sys_event_iter(const struct pmu_event *pe,
> > > return ret;
> > > }
> > >
> > > +/**
> > > + * metric_list_cmp - list_sort comparator that sorts metrics with more events to
> > > + * the front. duration_time is excluded from the count.
> > > + */
> > > static int metric_list_cmp(void *priv __maybe_unused, const struct list_head *l,
> > > const struct list_head *r)
> > > {
> > > const struct metric *left = container_of(l, struct metric, nd);
> > > const struct metric *right = container_of(r, struct metric, nd);
> > > + struct expr_id_data *data;
> > > + int left_count, right_count;
> > > +
> > > + left_count = hashmap__size(left->pctx->ids);
> > > + if (!expr__get_id(left->pctx, "duration_time", &data))
> > > + left_count--;
> > > +
> > > + right_count = hashmap__size(right->pctx->ids);
> > > + if (!expr__get_id(right->pctx, "duration_time", &data))
> > > + right_count--;
> > >
> > > - return hashmap__size(right->pctx->ids) - hashmap__size(left->pctx->ids);
> > > + return right_count - left_count;
> > > }
> > >
> > > /**
> > > @@ -1299,14 +1313,16 @@ static int build_combined_expr_ctx(const struct list_head *metric_list,
> > > /**
> > > * parse_ids - Build the event string for the ids and parse them creating an
> > > * evlist. The encoded metric_ids are decoded.
> > > + * @metric_no_merge: is metric sharing explicitly disabled.
> > > * @fake_pmu: used when testing metrics not supported by the current CPU.
> > > * @ids: the event identifiers parsed from a metric.
> > > * @modifier: any modifiers added to the events.
> > > * @has_constraint: false if events should be placed in a weak group.
> > > * @out_evlist: the created list of events.
> > > */
> > > -static int parse_ids(struct perf_pmu *fake_pmu, struct expr_parse_ctx *ids,
> > > - const char *modifier, bool has_constraint, struct evlist **out_evlist)
> > > +static int parse_ids(bool metric_no_merge, struct perf_pmu *fake_pmu,
> > > + struct expr_parse_ctx *ids, const char *modifier,
> > > + bool has_constraint, struct evlist **out_evlist)
> > > {
> > > struct parse_events_error parse_error;
> > > struct evlist *parsed_evlist;
> > > @@ -1314,12 +1330,19 @@ static int parse_ids(struct perf_pmu *fake_pmu, struct expr_parse_ctx *ids,
> > > int ret;
> > >
> > > *out_evlist = NULL;
> > > - if (hashmap__size(ids->ids) == 0) {
> > > + if (!metric_no_merge || hashmap__size(ids->ids) == 0) {
> > > char *tmp;
> > > /*
> > > - * No ids/events in the expression parsing context. Events may
> > > - * have been removed because of constant evaluation, e.g.:
> > > - * event1 if #smt_on else 0
> > > + * We may fail to share events between metrics because
> > > + * duration_time isn't present in one metric. For example, a
> > > + * ratio of cache misses doesn't need duration_time but the same
> > > + * events may be used for a misses per second. Events without
> > > + * sharing implies multiplexing, that is best avoided, so place
> > > + * duration_time in every group.
> > > + *
> > > + * Also, there may be no ids/events in the expression parsing
> > > + * context because of constant evaluation, e.g.:
> > > + * event1 if #smt_on else 0
> > > * Add a duration_time event to avoid a parse error on an empty
> > > * string.
> > > */
> > > @@ -1387,7 +1410,8 @@ static int parse_groups(struct evlist *perf_evlist, const char *str,
> > > ret = build_combined_expr_ctx(&metric_list, &combined);
> > >
> > > if (!ret && combined && hashmap__size(combined->ids)) {
> > > - ret = parse_ids(fake_pmu, combined, /*modifier=*/NULL,
> > > + ret = parse_ids(metric_no_merge, fake_pmu, combined,
> > > + /*modifier=*/NULL,
> > > /*has_constraint=*/true,
> > > &combined_evlist);
> > > }
> > > @@ -1435,7 +1459,7 @@ static int parse_groups(struct evlist *perf_evlist, const char *str,
> > > }
> > > }
> > > if (!metric_evlist) {
> > > - ret = parse_ids(fake_pmu, m->pctx, m->modifier,
> > > + ret = parse_ids(metric_no_merge, fake_pmu, m->pctx, m->modifier,
> > > m->has_constraint, &m->evlist);
> > > if (ret)
> > > goto out;
> > > --
> > > 2.34.0.rc2.393.gf8c9666880-goog
> > >
> >
>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH v2] perf metric: Reduce multiplexing with duration_time
2021-11-30 18:11 ` Jiri Olsa
@ 2021-11-30 19:24 ` Arnaldo Carvalho de Melo
0 siblings, 0 replies; 5+ messages in thread
From: Arnaldo Carvalho de Melo @ 2021-11-30 19:24 UTC (permalink / raw)
To: Jiri Olsa
Cc: Ian Rogers, Andi Kleen, Namhyung Kim, John Garry, Kajol Jain,
Paul A . Clarke, Kan Liang, Peter Zijlstra, Ingo Molnar,
Mark Rutland, Alexander Shishkin, linux-perf-users, linux-kernel,
eranian
Em Tue, Nov 30, 2021 at 07:11:36PM +0100, Jiri Olsa escreveu:
> On Mon, Nov 29, 2021 at 09:46:31AM -0800, Ian Rogers wrote:
> > On Sun, Nov 28, 2021 at 8:23 AM Jiri Olsa <jolsa@redhat.com> wrote:
> > >
> > > On Tue, Nov 23, 2021 at 05:52:26PM -0800, Ian Rogers wrote:
> > > > It is common to use the same counters with and without
> > > > duration_time. The ID sharing code treats duration_time as if it
> > > > were a hardware event placed in the same group. This causes
> > > > unnecessary multiplexing such as in the following example where
> > > > l3_cache_access isn't shared:
> > > >
> > > > $ perf stat -M l3 -a sleep 1
> > > >
> > > > Performance counter stats for 'system wide':
> > > >
> > > > 3,117,007 l3_cache_miss # 199.5 MB/s l3_rd_bw
> > > > # 43.6 % l3_hits
> > > > # 56.4 % l3_miss (50.00%)
> > > > 5,526,447 l3_cache_access (50.00%)
> > > > 5,392,435 l3_cache_access # 5389191.2 access/s l3_access_rate (50.00%)
> > > > 1,000,601,901 ns duration_time
> > > >
> > > > 1.000601901 seconds time elapsed
> > > >
> > > > Fix this by placing duration_time in all groups unless metric
> > > > sharing has been disabled on the command line:
> > > >
> > > > $ perf stat -M l3 -a sleep 1
> > > >
> > > > Performance counter stats for 'system wide':
> > > >
> > > > 3,597,972 l3_cache_miss # 230.3 MB/s l3_rd_bw
> > > > # 48.0 % l3_hits
> > > > # 52.0 % l3_miss
> > > > 6,914,459 l3_cache_access # 6909935.9 access/s l3_access_rate
> > > > 1,000,654,579 ns duration_time
> > > >
> > > > 1.000654579 seconds time elapsed
> > > >
> > > > $ perf stat --metric-no-merge -M l3 -a sleep 1
> > > >
> > > > Performance counter stats for 'system wide':
> > > >
> > > > 3,501,834 l3_cache_miss # 53.5 % l3_miss (24.99%)
> > > > 6,548,173 l3_cache_access (24.99%)
> > > > 3,417,622 l3_cache_miss # 45.7 % l3_hits (25.04%)
> > > > 6,294,062 l3_cache_access (25.04%)
> > > > 5,923,238 l3_cache_access # 5919688.1 access/s l3_access_rate (24.99%)
> > > > 1,000,599,683 ns duration_time
> > > > 3,607,486 l3_cache_miss # 230.9 MB/s l3_rd_bw (49.97%)
> > > >
> > > > 1.000599683 seconds time elapsed
> > > >
> > > > v2. Doesn't count duration_time in the metric_list_cmp function that
> > > > sorts larger metrics first. Without this a metric with duration_time
> > > > and an event is sorted the same as a metric with two events,
> > > > possibly not allowing the first metric to share with the second.
> > >
> > > hum, isn't the change about adding duration_time in every metric?
> > > or you could still end up with metric without duration_time
> >
> > It is about adding duration_time to all metrics. Sorting of the
> > metrics by number of IDs happens before we insert duration_time which
> > happens just prior to parsing. duration_time needn't be inserted if
> > --metric-no-merge is passed.
>
> I see, so that sorting takes place before it's added, makes sense then
>
> Acked-by: Jiri Olsa <jolsa@redhat.com>
Thanks, applied.
- Arnaldo
^ permalink raw reply [flat|nested] 5+ messages in thread
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2021-11-24 1:52 [PATCH v2] perf metric: Reduce multiplexing with duration_time Ian Rogers
2021-11-28 16:23 ` Jiri Olsa
2021-11-29 17:46 ` Ian Rogers
2021-11-30 18:11 ` Jiri Olsa
2021-11-30 19:24 ` Arnaldo Carvalho de Melo
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