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perf tools: Add support for exclusive groups/events
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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.

Committer testing:

  # perf test "parse event"
   6: Parse event definition strings                                  : Ok
  # perf test -v "parse event" |& grep :u*e
  running test 56 'instructions:uep'
  running test 57 '{cycles,cache-misses,branch-misses}:e'
  #
  #
  # grep "model name" -m1 /proc/cpuinfo
  model name	: AMD Ryzen 9 3900X 12-Core Processor
  #
  # perf stat -a -e '{cycles,cache-misses,branch-misses}:e' sleep 1

   Performance counter stats for 'system wide':

       <not counted>      cycles                                                        (0.00%)
       <not counted>      cache-misses                                                  (0.00%)
       <not counted>      branch-misses                                                 (0.00%)

         1.001269893 seconds time elapsed

  Some events weren't counted. Try disabling the NMI watchdog:
  	echo 0 > /proc/sys/kernel/nmi_watchdog
  	perf stat ...
  	echo 1 > /proc/sys/kernel/nmi_watchdog
  # echo 0 > /proc/sys/kernel/nmi_watchdog
  # perf stat -a -e '{cycles,cache-misses,branch-misses}:e' sleep 1

   Performance counter stats for 'system wide':

       1,298,663,141      cycles
          30,962,215      cache-misses
           5,325,150      branch-misses

         1.001474934 seconds time elapsed

  #
  # The output for asking for precise events on AMD needs to improve, it
  # supposedly works only for system wide or per CPU
  #
  # perf stat -a -e '{cycles,cache-misses,branch-misses}:uep' sleep 1
  Error:
  The sys_perf_event_open() syscall returned with 22 (Invalid argument) for event (cycles).
  /bin/dmesg | grep -i perf may provide additional information.

  # perf stat -a -e '{cycles,cache-misses,branch-misses}:ue' sleep 1

   Performance counter stats for 'system wide':

         746,363,126      cycles
          16,881,611      cache-misses
           2,871,259      branch-misses

         1.001636066 seconds time elapsed

  #

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20201014144255.22699-1-andi@firstfloor.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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Andi Kleen authored and Arnaldo Carvalho de Melo committed Oct 14, 2020
1 parent 78b2c50 commit 0997a26
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Showing 4 changed files with 68 additions and 4 deletions.
1 change: 1 addition & 0 deletions tools/perf/Documentation/perf-list.txt
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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:
Expand Down
58 changes: 57 additions & 1 deletion tools/perf/tests/parse-events.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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;
}
Expand All @@ -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);
Expand All @@ -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;
}
Expand Down Expand Up @@ -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);
Expand Down Expand Up @@ -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[] = {
Expand Down
11 changes: 9 additions & 2 deletions tools/perf/util/parse-events.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1775,6 +1775,7 @@ struct event_modifier {
int sample_read;
int pinned;
int weak;
int exclusive;
};

static int get_event_modifier(struct event_modifier *mod, char *str,
Expand All @@ -1790,6 +1791,7 @@ 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;
Expand Down Expand Up @@ -1833,6 +1835,8 @@ 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
Expand Down Expand Up @@ -1866,6 +1870,7 @@ 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;
}
Expand All @@ -1879,7 +1884,7 @@ static int check_modifier(char *str)
char *p = str;

/* The sizeof includes 0 byte as well. */
if (strlen(str) > (sizeof("ukhGHpppPSDIW") - 1))
if (strlen(str) > (sizeof("ukhGHpppPSDIWe") - 1))
return -1;

while (*p) {
Expand Down Expand Up @@ -1921,8 +1926,10 @@ 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;
Expand Down
2 changes: 1 addition & 1 deletion tools/perf/util/parse-events.l
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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() */
modifier_event [ukhpPGHSDIW]+
modifier_event [ukhpPGHSDIWe]+
modifier_bp [rwx]{1,3}

%%
Expand Down

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