diff options
author | Ravi Bangoria <ravi.bangoria@amd.com> | 2021-11-02 11:01:12 +0530 |
---|---|---|
committer | Arnaldo Carvalho de Melo <acme@redhat.com> | 2021-11-07 12:26:24 -0300 |
commit | eb39bf325631f9ae185abd16281079b7b9858737 (patch) | |
tree | 0c75e0918e5d0c34602bfe39741fa212cfe7ecae /tools/perf/util/evsel.c | |
parent | 3500eeebeda842e8499617b8983a4c55fd6bdfe3 (diff) |
perf evsel: Don't set exclude_guest by default
Perf tool sets exclude_guest by default while calling perf_event_open().
Because IBS does not have filtering capability, it always gets rejected
by IBS PMU driver and thus perf falls back to non-precise sampling. Fix
it by not setting exclude_guest by default on AMD.
Before:
$ sudo ./perf record -C 0 -vvv true |& grep precise
precise_ip 3
decreasing precise_ip by one (2)
precise_ip 2
decreasing precise_ip by one (1)
precise_ip 1
decreasing precise_ip by one (0)
After:
$ sudo ./perf record -C 0 -vvv true |& grep precise
precise_ip 3
decreasing precise_ip by one (2)
precise_ip 2
Committer notes:
Fixup init to zero for perf_env in older compilers:
arch/x86/util/evsel.c:15:26: error: missing field 'os_release' initializer [-Werror,-Wmissing-field-initializers]
struct perf_env env = {0};
^
Committer notes:
Namhyung remarked:
It'd be nice if it can cover explicit "-e cycles:pp" as well.
Ravi clarified:
For explicit :pp modifier, evsel->precise_max does not get set and thus perf
does not try with different attr->precise_ip values while exclude_guest set.
So no issue with explicit :pp:
$ sudo ./perf record -C 0 -e cycles:pp -vvv |& grep "precise_ip\|exclude_guest"
precise_ip 2
exclude_guest 1
precise_ip 2
exclude_guest 1
switching off exclude_guest, exclude_host
precise_ip 2
^C
Also, with :P modifier, evsel->precise_max gets set but exclude_guest does
not and thus :P also works fine:
$ sudo ./perf record -C 0 -e cycles:P -vvv |& grep "precise_ip\|exclude_guest"
precise_ip 3
decreasing precise_ip by one (2)
precise_ip 2
^C
Reported-by: Kim Phillips <kim.phillips@amd.com>
Signed-off-by: Ravi Bangoria <ravi.bangoria@amd.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lore.kernel.org/lkml/20211103072112.32312-1-ravi.bangoria@amd.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools/perf/util/evsel.c')
-rw-r--r-- | tools/perf/util/evsel.c | 12 |
1 files changed, 7 insertions, 5 deletions
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c index 3cc1f8fcf15c..ec967fb8d7d9 100644 --- a/tools/perf/util/evsel.c +++ b/tools/perf/util/evsel.c @@ -294,7 +294,7 @@ static bool perf_event_can_profile_kernel(void) return perf_event_paranoid_check(1); } -struct evsel *evsel__new_cycles(bool precise, __u32 type, __u64 config) +struct evsel *evsel__new_cycles(bool precise __maybe_unused, __u32 type, __u64 config) { struct perf_event_attr attr = { .type = type, @@ -305,18 +305,16 @@ struct evsel *evsel__new_cycles(bool precise, __u32 type, __u64 config) event_attr_init(&attr); - if (!precise) - goto new_event; - /* * Now let the usual logic to set up the perf_event_attr defaults * to kick in when we return and before perf_evsel__open() is called. */ -new_event: evsel = evsel__new(&attr); if (evsel == NULL) goto out; + arch_evsel__fixup_new_cycles(&evsel->core.attr); + evsel->precise_max = true; /* use asprintf() because free(evsel) assumes name is allocated */ @@ -1063,6 +1061,10 @@ void __weak arch_evsel__set_sample_weight(struct evsel *evsel) evsel__set_sample_bit(evsel, WEIGHT); } +void __weak arch_evsel__fixup_new_cycles(struct perf_event_attr *attr __maybe_unused) +{ +} + /* * The enable_on_exec/disabled value strategy: * |