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Date: Wed, 14 Oct 2020 15:49:47 +0200
From: Jiri Olsa <jolsa@...hat.com>
To: Andi Kleen <andi@...stfloor.org>
Cc: acme@...nel.org, linux-kernel@...r.kernel.org, jolsa@...nel.org,
peterz@...radead.org, Andi Kleen <ak@...ux.intel.com>
Subject: Re: [PATCH] perf: Add support for exclusive groups/events
On Tue, Oct 13, 2020 at 08:52:03PM -0700, Andi Kleen wrote:
> Peter suggested that using the exclusive mode in perf could
> avoid some problems with bad scheduling of groups. Exclusive
> is implemented in the kernel, but wasn't exposed by the perf tool,
> so hard to use without custom low level API users.
>
> Add support for marking groups or events with :e for exclusive
> in the perf tool. The implementation is basically the same as the
> existing pinned attribute.
>
> Cc: peterz@...radead.org
> Signed-off-by: Andi Kleen <ak@...ux.intel.com>
> ---
> tools/perf/Documentation/perf-list.txt | 1 +
> tools/perf/tests/parse-events.c | 58 +++++++++++++++++++++++++-
> tools/perf/util/parse-events.c | 9 +++-
> tools/perf/util/parse-events.l | 2 +-
> 4 files changed, 67 insertions(+), 3 deletions(-)
>
> diff --git a/tools/perf/Documentation/perf-list.txt b/tools/perf/Documentation/perf-list.txt
> index 10ed539a8859..4c7db1da8fcc 100644
> --- a/tools/perf/Documentation/perf-list.txt
> +++ b/tools/perf/Documentation/perf-list.txt
> @@ -58,6 +58,7 @@ counted. The following modifiers exist:
> S - read sample value (PERF_SAMPLE_READ)
> D - pin the event to the PMU
> W - group is weak and will fallback to non-group if not schedulable,
> + e - group or event are exclusive and do not share the PMU
>
> The 'p' modifier can be used for specifying how precise the instruction
> address should be. The 'p' modifier can be specified multiple times:
> diff --git a/tools/perf/tests/parse-events.c b/tools/perf/tests/parse-events.c
> index 7f9f87a470c3..7411dd4d76cf 100644
> --- a/tools/perf/tests/parse-events.c
> +++ b/tools/perf/tests/parse-events.c
> @@ -557,6 +557,7 @@ static int test__checkevent_pmu_events(struct evlist *evlist)
> TEST_ASSERT_VAL("wrong exclude_hv", evsel->core.attr.exclude_hv);
> TEST_ASSERT_VAL("wrong precise_ip", !evsel->core.attr.precise_ip);
> TEST_ASSERT_VAL("wrong pinned", !evsel->core.attr.pinned);
> + TEST_ASSERT_VAL("wrong exclusive", !evsel->core.attr.exclusive);
>
> return 0;
> }
> @@ -575,6 +576,7 @@ static int test__checkevent_pmu_events_mix(struct evlist *evlist)
> TEST_ASSERT_VAL("wrong exclude_hv", evsel->core.attr.exclude_hv);
> TEST_ASSERT_VAL("wrong precise_ip", !evsel->core.attr.precise_ip);
> TEST_ASSERT_VAL("wrong pinned", !evsel->core.attr.pinned);
> + TEST_ASSERT_VAL("wrong exclusive", !evsel->core.attr.exclusive);
>
> /* cpu/pmu-event/u*/
> evsel = evsel__next(evsel);
> @@ -587,6 +589,7 @@ static int test__checkevent_pmu_events_mix(struct evlist *evlist)
> TEST_ASSERT_VAL("wrong exclude_hv", evsel->core.attr.exclude_hv);
> TEST_ASSERT_VAL("wrong precise_ip", !evsel->core.attr.precise_ip);
> TEST_ASSERT_VAL("wrong pinned", !evsel->core.attr.pinned);
> + TEST_ASSERT_VAL("wrong exclusive", !evsel->core.attr.pinned);
>
> return 0;
> }
> @@ -1277,6 +1280,49 @@ static int test__pinned_group(struct evlist *evlist)
> return 0;
> }
>
> +static int test__checkevent_exclusive_modifier(struct evlist *evlist)
> +{
> + struct evsel *evsel = evlist__first(evlist);
> +
> + TEST_ASSERT_VAL("wrong exclude_user", !evsel->core.attr.exclude_user);
> + TEST_ASSERT_VAL("wrong exclude_kernel", evsel->core.attr.exclude_kernel);
> + TEST_ASSERT_VAL("wrong exclude_hv", evsel->core.attr.exclude_hv);
> + TEST_ASSERT_VAL("wrong precise_ip", evsel->core.attr.precise_ip);
> + TEST_ASSERT_VAL("wrong exclusive", evsel->core.attr.exclusive);
> +
> + return test__checkevent_symbolic_name(evlist);
> +}
> +
> +static int test__exclusive_group(struct evlist *evlist)
> +{
> + struct evsel *evsel, *leader;
> +
> + TEST_ASSERT_VAL("wrong number of entries", 3 == evlist->core.nr_entries);
> +
> + /* cycles - group leader */
> + evsel = leader = evlist__first(evlist);
> + TEST_ASSERT_VAL("wrong type", PERF_TYPE_HARDWARE == evsel->core.attr.type);
> + TEST_ASSERT_VAL("wrong config",
> + PERF_COUNT_HW_CPU_CYCLES == evsel->core.attr.config);
> + TEST_ASSERT_VAL("wrong group name", !evsel->group_name);
> + TEST_ASSERT_VAL("wrong leader", evsel->leader == leader);
> + TEST_ASSERT_VAL("wrong exclusive", evsel->core.attr.exclusive);
> +
> + /* cache-misses - can not be pinned, but will go on with the leader */
> + evsel = evsel__next(evsel);
> + TEST_ASSERT_VAL("wrong type", PERF_TYPE_HARDWARE == evsel->core.attr.type);
> + TEST_ASSERT_VAL("wrong config",
> + PERF_COUNT_HW_CACHE_MISSES == evsel->core.attr.config);
> + TEST_ASSERT_VAL("wrong exclusive", !evsel->core.attr.exclusive);
> +
> + /* branch-misses - ditto */
> + evsel = evsel__next(evsel);
> + TEST_ASSERT_VAL("wrong config",
> + PERF_COUNT_HW_BRANCH_MISSES == evsel->core.attr.config);
> + TEST_ASSERT_VAL("wrong exclusive", !evsel->core.attr.exclusive);
> +
> + return 0;
> +}
> static int test__checkevent_breakpoint_len(struct evlist *evlist)
> {
> struct evsel *evsel = evlist__first(evlist);
> @@ -1765,7 +1811,17 @@ static struct evlist_test test__events[] = {
> .name = "cycles:k",
> .check = test__sym_event_dc,
> .id = 55,
> - }
> + },
> + {
> + .name = "instructions:uep",
> + .check = test__checkevent_exclusive_modifier,
> + .id = 56,
> + },
> + {
> + .name = "{cycles,cache-misses,branch-misses}:e",
> + .check = test__exclusive_group,
> + .id = 57,
> + },
> };
>
> static struct evlist_test test__events_pmu[] = {
> diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
> index 9f7260e69113..760506f7a87a 100644
> --- a/tools/perf/util/parse-events.c
> +++ b/tools/perf/util/parse-events.c
> @@ -1768,6 +1768,7 @@ struct event_modifier {
> int sample_read;
> int pinned;
> int weak;
> + int exclusive;
> };
>
> static int get_event_modifier(struct event_modifier *mod, char *str,
> @@ -1783,6 +1784,7 @@ static int get_event_modifier(struct event_modifier *mod, char *str,
> int precise_max = 0;
> int sample_read = 0;
> int pinned = evsel ? evsel->core.attr.pinned : 0;
> + int exclusive = evsel ? evsel->core.attr.exclusive : 0;
>
> int exclude = eu | ek | eh;
> int exclude_GH = evsel ? evsel->exclude_GH : 0;
> @@ -1824,6 +1826,8 @@ static int get_event_modifier(struct event_modifier *mod, char *str,
> sample_read = 1;
> } else if (*str == 'D') {
> pinned = 1;
> + } else if (*str == 'e') {
> + exclusive = 1;
> } else if (*str == 'W') {
> weak = 1;
> } else
> @@ -1857,6 +1861,7 @@ static int get_event_modifier(struct event_modifier *mod, char *str,
> mod->sample_read = sample_read;
> mod->pinned = pinned;
> mod->weak = weak;
> + mod->exclusive = exclusive;
>
> return 0;
> }
> @@ -1912,8 +1917,10 @@ int parse_events__modifier_event(struct list_head *list, char *str, bool add)
> evsel->precise_max = mod.precise_max;
> evsel->weak_group = mod.weak;
>
> - if (evsel__is_group_leader(evsel))
> + if (evsel__is_group_leader(evsel)) {
> evsel->core.attr.pinned = mod.pinned;
> + evsel->core.attr.exclusive = mod.exclusive;
> + }
> }
>
> return 0;
> diff --git a/tools/perf/util/parse-events.l b/tools/perf/util/parse-events.l
> index 3ca5fd2829ca..9db5097317f4 100644
> --- a/tools/perf/util/parse-events.l
> +++ b/tools/perf/util/parse-events.l
> @@ -210,7 +210,7 @@ name_tag [\'][a-zA-Z_*?\[\]][a-zA-Z0-9_*?\-,\.\[\]:=]*[\']
> name_minus [a-zA-Z_*?][a-zA-Z0-9\-_*?.:]*
> drv_cfg_term [a-zA-Z0-9_\.]+(=[a-zA-Z0-9_*?\.:]+)?
> /* If you add a modifier you need to update check_modifier() */
please update also check_modifier function as the comment
suggests, other than that it looks good to me
thanks,
jrka
> -modifier_event [ukhpPGHSDIW]+
> +modifier_event [ukhpPGHSDIWe]+
> modifier_bp [rwx]{1,3}
>
> %%
> --
> 2.28.0
>
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