[PATCH v2] perf evsel: Fix missing exclude_{host,guest} setting

[PATCH v2] perf evsel: Fix missing exclude_{host,guest} setting

[Namhyung Kim]

The current logic for the perf missing feature has a bug that it can
wrongly clear some modifiers like G or H.  Actually some PMUs don't
support any filtering or exclusion while others do.  But we check it
as a global feature.

For example, the cycles event can have 'G' modifier to enable it only
in the guest mode on x86.  When you don't run any VMs it'll return 0.

  # perf stat -a -e cycles:G sleep 1

    Performance counter stats for 'system wide':

                    0      cycles:G

          1.000721670 seconds time elapsed

But when it's used with other pmu events that don't support G modifier,
it'll be reset and return non-zero values.

  # perf stat -a -e cycles:G,msr/tsc/ sleep 1

    Performance counter stats for 'system wide':

          538,029,960      cycles:G
       16,924,010,738      msr/tsc/

          1.001815327 seconds time elapsed

This is because of the missing feature detection logic being global.
Add a hashmap to set pmu-specific exclude_host/guest features.

Reported-by: Stephane Eranian <eranian@google.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
v2 changes)
 * change to enum perf_missing_pmu_features
 * pass NULL to hashmap__find() to skip checking
 * add a blank line after declaration

 tools/perf/util/evsel.c | 47 +++++++++++++++++++++++++++++++++++------
 tools/perf/util/evsel.h |  7 ++++++
 2 files changed, 48 insertions(+), 6 deletions(-)

diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index dbfeceb2546c..f33801b4615d 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -1434,6 +1434,10 @@ void evsel__delete(struct evsel *evsel)
 {
 	evsel__exit(evsel);
 	free(evsel);
+
+	/* just free it for the first evsel */
+	hashmap__free(perf_missing_features.pmu);
+	perf_missing_features.pmu = NULL;
 }
 
 void evsel__compute_deltas(struct evsel *evsel, int cpu, int thread,
@@ -1791,6 +1795,23 @@ static int __evsel__prepare_open(struct evsel *evsel, struct perf_cpu_map *cpus,
 	return 0;
 }
 
+#define PMU_HASH_BITS  4
+
+static size_t pmu_hash(const void *key, void *ctx __maybe_unused)
+{
+	const struct evsel *evsel = key;
+
+	return hash_bits(evsel->core.attr.type, PMU_HASH_BITS);
+}
+
+static bool pmu_equal(const void *key1, const void *key2, void *ctx __maybe_unused)
+{
+	const struct evsel *a = key1;
+	const struct evsel *b = key2;
+
+	return a->core.attr.type == b->core.attr.type;
+}
+
 static void evsel__disable_missing_features(struct evsel *evsel)
 {
 	if (perf_missing_features.weight_struct) {
@@ -1807,8 +1828,13 @@ static void evsel__disable_missing_features(struct evsel *evsel)
 		evsel->open_flags &= ~(unsigned long)PERF_FLAG_FD_CLOEXEC;
 	if (perf_missing_features.mmap2)
 		evsel->core.attr.mmap2 = 0;
-	if (perf_missing_features.exclude_guest)
-		evsel->core.attr.exclude_guest = evsel->core.attr.exclude_host = 0;
+	if (perf_missing_features.exclude_guest) {
+		/* we only have EXCLUDE_GUEST bit, let's skip checking  */
+		if (hashmap__find(perf_missing_features.pmu, evsel, NULL)) {
+			evsel->core.attr.exclude_guest = 0;
+			evsel->core.attr.exclude_host = 0;
+		}
+	}
 	if (perf_missing_features.lbr_flags)
 		evsel->core.attr.branch_sample_type &= ~(PERF_SAMPLE_BRANCH_NO_FLAGS |
 				     PERF_SAMPLE_BRANCH_NO_CYCLES);
@@ -1840,6 +1866,9 @@ int evsel__prepare_open(struct evsel *evsel, struct perf_cpu_map *cpus,
 
 bool evsel__detect_missing_features(struct evsel *evsel)
 {
+	if (perf_missing_features.pmu == NULL)
+		perf_missing_features.pmu = hashmap__new(pmu_hash, pmu_equal, NULL);
+
 	/*
 	 * Must probe features in the order they were added to the
 	 * perf_event_attr interface.
@@ -1900,10 +1929,16 @@ bool evsel__detect_missing_features(struct evsel *evsel)
 		perf_missing_features.mmap2 = true;
 		pr_debug2_peo("switching off mmap2\n");
 		return true;
-	} else if (!perf_missing_features.exclude_guest &&
-		   (evsel->core.attr.exclude_guest || evsel->core.attr.exclude_host)) {
-		perf_missing_features.exclude_guest = true;
-		pr_debug2_peo("switching off exclude_guest, exclude_host\n");
+	} else if ((evsel->core.attr.exclude_guest || evsel->core.attr.exclude_host) &&
+		   !hashmap__find(perf_missing_features.pmu, evsel, NULL)) {
+		uintptr_t pmu_features = PERF_MISSING_PMU_EXCLUDE_GUEST;
+
+		hashmap__add(perf_missing_features.pmu, evsel, (void *)pmu_features);
+
+		if (!perf_missing_features.exclude_guest) {
+			perf_missing_features.exclude_guest = true;
+			pr_debug2_peo("switching off exclude_guest, exclude_host\n");
+		}
 		return true;
 	} else if (!perf_missing_features.sample_id_all) {
 		perf_missing_features.sample_id_all = true;
diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h
index 1f7edfa8568a..11b5ece19f0e 100644
--- a/tools/perf/util/evsel.h
+++ b/tools/perf/util/evsel.h
@@ -172,6 +172,13 @@ struct perf_missing_features {
 	bool data_page_size;
 	bool code_page_size;
 	bool weight_struct;
+
+	/* contains enum perf_missing_pmu_features below */
+	struct hashmap *pmu;
+};
+
+enum perf_missing_pmu_features {
+	PERF_MISSING_PMU_EXCLUDE_GUEST		= 1UL << 0,
 };
 
 extern struct perf_missing_features perf_missing_features;
-- 
2.33.0.1079.g6e70778dc9-goog

Re: [PATCH v2] perf evsel: Fix missing exclude_{host,guest} setting

[Jiri Olsa]

On Mon, Oct 25, 2021 at 09:33:51PM -0700, Namhyung Kim wrote:
> The current logic for the perf missing feature has a bug that it can
> wrongly clear some modifiers like G or H.  Actually some PMUs don't
> support any filtering or exclusion while others do.  But we check it
> as a global feature.
> 
> For example, the cycles event can have 'G' modifier to enable it only
> in the guest mode on x86.  When you don't run any VMs it'll return 0.
> 
>   # perf stat -a -e cycles:G sleep 1
> 
>     Performance counter stats for 'system wide':
> 
>                     0      cycles:G
> 
>           1.000721670 seconds time elapsed
> 
> But when it's used with other pmu events that don't support G modifier,
> it'll be reset and return non-zero values.
> 
>   # perf stat -a -e cycles:G,msr/tsc/ sleep 1
> 
>     Performance counter stats for 'system wide':
> 
>           538,029,960      cycles:G
>        16,924,010,738      msr/tsc/
> 
>           1.001815327 seconds time elapsed
> 
> This is because of the missing feature detection logic being global.
> Add a hashmap to set pmu-specific exclude_host/guest features.
> 
> Reported-by: Stephane Eranian <eranian@google.com>
> Signed-off-by: Namhyung Kim <namhyung@kernel.org>
> ---
> v2 changes)
>  * change to enum perf_missing_pmu_features
>  * pass NULL to hashmap__find() to skip checking
>  * add a blank line after declaration
> 
>  tools/perf/util/evsel.c | 47 +++++++++++++++++++++++++++++++++++------
>  tools/perf/util/evsel.h |  7 ++++++
>  2 files changed, 48 insertions(+), 6 deletions(-)
> 
> diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
> index dbfeceb2546c..f33801b4615d 100644
> --- a/tools/perf/util/evsel.c
> +++ b/tools/perf/util/evsel.c
> @@ -1434,6 +1434,10 @@ void evsel__delete(struct evsel *evsel)
>  {
>  	evsel__exit(evsel);
>  	free(evsel);
> +
> +	/* just free it for the first evsel */
> +	hashmap__free(perf_missing_features.pmu);
> +	perf_missing_features.pmu = NULL;

should this just remove evsel from perf_missing_features.pmu?

I'm not sure when we should actually release this.. what's your rationale
for releasing it in here?

>  }
>  
>  void evsel__compute_deltas(struct evsel *evsel, int cpu, int thread,
> @@ -1791,6 +1795,23 @@ static int __evsel__prepare_open(struct evsel *evsel, struct perf_cpu_map *cpus,
>  	return 0;
>  }
>  
> +#define PMU_HASH_BITS  4
> +
> +static size_t pmu_hash(const void *key, void *ctx __maybe_unused)
> +{
> +	const struct evsel *evsel = key;
> +
> +	return hash_bits(evsel->core.attr.type, PMU_HASH_BITS);
> +}
> +
> +static bool pmu_equal(const void *key1, const void *key2, void *ctx __maybe_unused)
> +{
> +	const struct evsel *a = key1;
> +	const struct evsel *b = key2;
> +
> +	return a->core.attr.type == b->core.attr.type;
> +}
> +
>  static void evsel__disable_missing_features(struct evsel *evsel)
>  {
>  	if (perf_missing_features.weight_struct) {
> @@ -1807,8 +1828,13 @@ static void evsel__disable_missing_features(struct evsel *evsel)
>  		evsel->open_flags &= ~(unsigned long)PERF_FLAG_FD_CLOEXEC;
>  	if (perf_missing_features.mmap2)
>  		evsel->core.attr.mmap2 = 0;
> -	if (perf_missing_features.exclude_guest)
> -		evsel->core.attr.exclude_guest = evsel->core.attr.exclude_host = 0;
> +	if (perf_missing_features.exclude_guest) {
> +		/* we only have EXCLUDE_GUEST bit, let's skip checking  */
> +		if (hashmap__find(perf_missing_features.pmu, evsel, NULL)) {
> +			evsel->core.attr.exclude_guest = 0;
> +			evsel->core.attr.exclude_host = 0;
> +		}
> +	}
>  	if (perf_missing_features.lbr_flags)
>  		evsel->core.attr.branch_sample_type &= ~(PERF_SAMPLE_BRANCH_NO_FLAGS |
>  				     PERF_SAMPLE_BRANCH_NO_CYCLES);
> @@ -1840,6 +1866,9 @@ int evsel__prepare_open(struct evsel *evsel, struct perf_cpu_map *cpus,
>  
>  bool evsel__detect_missing_features(struct evsel *evsel)
>  {
> +	if (perf_missing_features.pmu == NULL)
> +		perf_missing_features.pmu = hashmap__new(pmu_hash, pmu_equal, NULL);

missing allocation fail check

thanks,
jirka

> +
>  	/*
>  	 * Must probe features in the order they were added to the
>  	 * perf_event_attr interface.
> @@ -1900,10 +1929,16 @@ bool evsel__detect_missing_features(struct evsel *evsel)
>  		perf_missing_features.mmap2 = true;
>  		pr_debug2_peo("switching off mmap2\n");
>  		return true;
> -	} else if (!perf_missing_features.exclude_guest &&
> -		   (evsel->core.attr.exclude_guest || evsel->core.attr.exclude_host)) {
> -		perf_missing_features.exclude_guest = true;
> -		pr_debug2_peo("switching off exclude_guest, exclude_host\n");
> +	} else if ((evsel->core.attr.exclude_guest || evsel->core.attr.exclude_host) &&
> +		   !hashmap__find(perf_missing_features.pmu, evsel, NULL)) {
> +		uintptr_t pmu_features = PERF_MISSING_PMU_EXCLUDE_GUEST;
> +
> +		hashmap__add(perf_missing_features.pmu, evsel, (void *)pmu_features);
> +
> +		if (!perf_missing_features.exclude_guest) {
> +			perf_missing_features.exclude_guest = true;
> +			pr_debug2_peo("switching off exclude_guest, exclude_host\n");
> +		}
>  		return true;
>  	} else if (!perf_missing_features.sample_id_all) {
>  		perf_missing_features.sample_id_all = true;
> diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h
> index 1f7edfa8568a..11b5ece19f0e 100644
> --- a/tools/perf/util/evsel.h
> +++ b/tools/perf/util/evsel.h
> @@ -172,6 +172,13 @@ struct perf_missing_features {
>  	bool data_page_size;
>  	bool code_page_size;
>  	bool weight_struct;
> +
> +	/* contains enum perf_missing_pmu_features below */
> +	struct hashmap *pmu;
> +};
> +
> +enum perf_missing_pmu_features {
> +	PERF_MISSING_PMU_EXCLUDE_GUEST		= 1UL << 0,
>  };
>  
>  extern struct perf_missing_features perf_missing_features;
> -- 
> 2.33.0.1079.g6e70778dc9-goog
> 

Re: [PATCH v2] perf evsel: Fix missing exclude_{host,guest} setting

[Namhyung Kim]

Hi Jiri,

On Tue, Oct 26, 2021 at 11:32 AM Jiri Olsa <jolsa@redhat.com> wrote:
>
> On Mon, Oct 25, 2021 at 09:33:51PM -0700, Namhyung Kim wrote:
> > The current logic for the perf missing feature has a bug that it can
> > wrongly clear some modifiers like G or H.  Actually some PMUs don't
> > support any filtering or exclusion while others do.  But we check it
> > as a global feature.
> >
> > For example, the cycles event can have 'G' modifier to enable it only
> > in the guest mode on x86.  When you don't run any VMs it'll return 0.
> >
> >   # perf stat -a -e cycles:G sleep 1
> >
> >     Performance counter stats for 'system wide':
> >
> >                     0      cycles:G
> >
> >           1.000721670 seconds time elapsed
> >
> > But when it's used with other pmu events that don't support G modifier,
> > it'll be reset and return non-zero values.
> >
> >   # perf stat -a -e cycles:G,msr/tsc/ sleep 1
> >
> >     Performance counter stats for 'system wide':
> >
> >           538,029,960      cycles:G
> >        16,924,010,738      msr/tsc/
> >
> >           1.001815327 seconds time elapsed
> >
> > This is because of the missing feature detection logic being global.
> > Add a hashmap to set pmu-specific exclude_host/guest features.
> >
> > Reported-by: Stephane Eranian <eranian@google.com>
> > Signed-off-by: Namhyung Kim <namhyung@kernel.org>
> > ---
> > v2 changes)
> >  * change to enum perf_missing_pmu_features
> >  * pass NULL to hashmap__find() to skip checking
> >  * add a blank line after declaration
> >
> >  tools/perf/util/evsel.c | 47 +++++++++++++++++++++++++++++++++++------
> >  tools/perf/util/evsel.h |  7 ++++++
> >  2 files changed, 48 insertions(+), 6 deletions(-)
> >
> > diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
> > index dbfeceb2546c..f33801b4615d 100644
> > --- a/tools/perf/util/evsel.c
> > +++ b/tools/perf/util/evsel.c
> > @@ -1434,6 +1434,10 @@ void evsel__delete(struct evsel *evsel)
> >  {
> >       evsel__exit(evsel);
> >       free(evsel);
> > +
> > +     /* just free it for the first evsel */
> > +     hashmap__free(perf_missing_features.pmu);
> > +     perf_missing_features.pmu = NULL;
>
> should this just remove evsel from perf_missing_features.pmu?

Nop, it'll release all the hash nodes (pmu).  Each evsel can come
from a same PMU.

>
> I'm not sure when we should actually release this.. what's your rationale
> for releasing it in here?

Yeah, that's a problem when we should release it.  Maybe we can
add a function and call it in the exit path but I didn't want to change
all the callsites just for this.

As evsel__delete() is called in the exit path, I thought it's a
place where we can free the hashmap.  But I'm not very happy
with that either.. Do you have a better idea?

If another evsel is open after this function, I think it should
be fine since it will create a new hash map and check the
missing feature again.


>
> >  }
> >
> >  void evsel__compute_deltas(struct evsel *evsel, int cpu, int thread,
> > @@ -1791,6 +1795,23 @@ static int __evsel__prepare_open(struct evsel *evsel, struct perf_cpu_map *cpus,
> >       return 0;
> >  }
> >
> > +#define PMU_HASH_BITS  4
> > +
> > +static size_t pmu_hash(const void *key, void *ctx __maybe_unused)
> > +{
> > +     const struct evsel *evsel = key;
> > +
> > +     return hash_bits(evsel->core.attr.type, PMU_HASH_BITS);
> > +}
> > +
> > +static bool pmu_equal(const void *key1, const void *key2, void *ctx __maybe_unused)
> > +{
> > +     const struct evsel *a = key1;
> > +     const struct evsel *b = key2;
> > +
> > +     return a->core.attr.type == b->core.attr.type;
> > +}
> > +
> >  static void evsel__disable_missing_features(struct evsel *evsel)
> >  {
> >       if (perf_missing_features.weight_struct) {
> > @@ -1807,8 +1828,13 @@ static void evsel__disable_missing_features(struct evsel *evsel)
> >               evsel->open_flags &= ~(unsigned long)PERF_FLAG_FD_CLOEXEC;
> >       if (perf_missing_features.mmap2)
> >               evsel->core.attr.mmap2 = 0;
> > -     if (perf_missing_features.exclude_guest)
> > -             evsel->core.attr.exclude_guest = evsel->core.attr.exclude_host = 0;
> > +     if (perf_missing_features.exclude_guest) {
> > +             /* we only have EXCLUDE_GUEST bit, let's skip checking  */
> > +             if (hashmap__find(perf_missing_features.pmu, evsel, NULL)) {
> > +                     evsel->core.attr.exclude_guest = 0;
> > +                     evsel->core.attr.exclude_host = 0;
> > +             }
> > +     }
> >       if (perf_missing_features.lbr_flags)
> >               evsel->core.attr.branch_sample_type &= ~(PERF_SAMPLE_BRANCH_NO_FLAGS |
> >                                    PERF_SAMPLE_BRANCH_NO_CYCLES);
> > @@ -1840,6 +1866,9 @@ int evsel__prepare_open(struct evsel *evsel, struct perf_cpu_map *cpus,
> >
> >  bool evsel__detect_missing_features(struct evsel *evsel)
> >  {
> > +     if (perf_missing_features.pmu == NULL)
> > +             perf_missing_features.pmu = hashmap__new(pmu_hash, pmu_equal, NULL);
>
> missing allocation fail check

Ok, will change.

Thanks for your review,
Namhyung


>
> > +
> >       /*
> >        * Must probe features in the order they were added to the
> >        * perf_event_attr interface.
> > @@ -1900,10 +1929,16 @@ bool evsel__detect_missing_features(struct evsel *evsel)
> >               perf_missing_features.mmap2 = true;
> >               pr_debug2_peo("switching off mmap2\n");
> >               return true;
> > -     } else if (!perf_missing_features.exclude_guest &&
> > -                (evsel->core.attr.exclude_guest || evsel->core.attr.exclude_host)) {
> > -             perf_missing_features.exclude_guest = true;
> > -             pr_debug2_peo("switching off exclude_guest, exclude_host\n");
> > +     } else if ((evsel->core.attr.exclude_guest || evsel->core.attr.exclude_host) &&
> > +                !hashmap__find(perf_missing_features.pmu, evsel, NULL)) {
> > +             uintptr_t pmu_features = PERF_MISSING_PMU_EXCLUDE_GUEST;
> > +
> > +             hashmap__add(perf_missing_features.pmu, evsel, (void *)pmu_features);
> > +
> > +             if (!perf_missing_features.exclude_guest) {
> > +                     perf_missing_features.exclude_guest = true;
> > +                     pr_debug2_peo("switching off exclude_guest, exclude_host\n");
> > +             }
> >               return true;
> >       } else if (!perf_missing_features.sample_id_all) {
> >               perf_missing_features.sample_id_all = true;
> > diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h
> > index 1f7edfa8568a..11b5ece19f0e 100644
> > --- a/tools/perf/util/evsel.h
> > +++ b/tools/perf/util/evsel.h
> > @@ -172,6 +172,13 @@ struct perf_missing_features {
> >       bool data_page_size;
> >       bool code_page_size;
> >       bool weight_struct;
> > +
> > +     /* contains enum perf_missing_pmu_features below */
> > +     struct hashmap *pmu;
> > +};
> > +
> > +enum perf_missing_pmu_features {
> > +     PERF_MISSING_PMU_EXCLUDE_GUEST          = 1UL << 0,
> >  };
> >
> >  extern struct perf_missing_features perf_missing_features;
> > --
> > 2.33.0.1079.g6e70778dc9-goog
> >
>

Re: [PATCH v2] perf evsel: Fix missing exclude_{host,guest} setting

[Jiri Olsa]

On Tue, Oct 26, 2021 at 12:30:42PM -0700, Namhyung Kim wrote:
> Hi Jiri,
> 
> On Tue, Oct 26, 2021 at 11:32 AM Jiri Olsa <jolsa@redhat.com> wrote:
> >
> > On Mon, Oct 25, 2021 at 09:33:51PM -0700, Namhyung Kim wrote:
> > > The current logic for the perf missing feature has a bug that it can
> > > wrongly clear some modifiers like G or H.  Actually some PMUs don't
> > > support any filtering or exclusion while others do.  But we check it
> > > as a global feature.
> > >
> > > For example, the cycles event can have 'G' modifier to enable it only
> > > in the guest mode on x86.  When you don't run any VMs it'll return 0.
> > >
> > >   # perf stat -a -e cycles:G sleep 1
> > >
> > >     Performance counter stats for 'system wide':
> > >
> > >                     0      cycles:G
> > >
> > >           1.000721670 seconds time elapsed
> > >
> > > But when it's used with other pmu events that don't support G modifier,
> > > it'll be reset and return non-zero values.
> > >
> > >   # perf stat -a -e cycles:G,msr/tsc/ sleep 1
> > >
> > >     Performance counter stats for 'system wide':
> > >
> > >           538,029,960      cycles:G
> > >        16,924,010,738      msr/tsc/
> > >
> > >           1.001815327 seconds time elapsed
> > >
> > > This is because of the missing feature detection logic being global.
> > > Add a hashmap to set pmu-specific exclude_host/guest features.
> > >
> > > Reported-by: Stephane Eranian <eranian@google.com>
> > > Signed-off-by: Namhyung Kim <namhyung@kernel.org>
> > > ---
> > > v2 changes)
> > >  * change to enum perf_missing_pmu_features
> > >  * pass NULL to hashmap__find() to skip checking
> > >  * add a blank line after declaration
> > >
> > >  tools/perf/util/evsel.c | 47 +++++++++++++++++++++++++++++++++++------
> > >  tools/perf/util/evsel.h |  7 ++++++
> > >  2 files changed, 48 insertions(+), 6 deletions(-)
> > >
> > > diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
> > > index dbfeceb2546c..f33801b4615d 100644
> > > --- a/tools/perf/util/evsel.c
> > > +++ b/tools/perf/util/evsel.c
> > > @@ -1434,6 +1434,10 @@ void evsel__delete(struct evsel *evsel)
> > >  {
> > >       evsel__exit(evsel);
> > >       free(evsel);
> > > +
> > > +     /* just free it for the first evsel */
> > > +     hashmap__free(perf_missing_features.pmu);
> > > +     perf_missing_features.pmu = NULL;
> >
> > should this just remove evsel from perf_missing_features.pmu?
> 
> Nop, it'll release all the hash nodes (pmu).  Each evsel can come
> from a same PMU.
> 
> >
> > I'm not sure when we should actually release this.. what's your rationale
> > for releasing it in here?
> 
> Yeah, that's a problem when we should release it.  Maybe we can
> add a function and call it in the exit path but I didn't want to change
> all the callsites just for this.

yea, I think we probably need it in other places as well,
but that should be separate patchset I think

> 
> As evsel__delete() is called in the exit path, I thought it's a
> place where we can free the hashmap.  But I'm not very happy
> with that either.. Do you have a better idea?

nope ;-)

> 
> If another evsel is open after this function, I think it should
> be fine since it will create a new hash map and check the
> missing feature again.

I think let's keep it as it is for now and we'll see

thanks,
jirka

> 
> 
> >
> > >  }
> > >
> > >  void evsel__compute_deltas(struct evsel *evsel, int cpu, int thread,
> > > @@ -1791,6 +1795,23 @@ static int __evsel__prepare_open(struct evsel *evsel, struct perf_cpu_map *cpus,
> > >       return 0;
> > >  }
> > >
> > > +#define PMU_HASH_BITS  4
> > > +
> > > +static size_t pmu_hash(const void *key, void *ctx __maybe_unused)
> > > +{
> > > +     const struct evsel *evsel = key;
> > > +
> > > +     return hash_bits(evsel->core.attr.type, PMU_HASH_BITS);
> > > +}
> > > +
> > > +static bool pmu_equal(const void *key1, const void *key2, void *ctx __maybe_unused)
> > > +{
> > > +     const struct evsel *a = key1;
> > > +     const struct evsel *b = key2;
> > > +
> > > +     return a->core.attr.type == b->core.attr.type;
> > > +}
> > > +
> > >  static void evsel__disable_missing_features(struct evsel *evsel)
> > >  {
> > >       if (perf_missing_features.weight_struct) {
> > > @@ -1807,8 +1828,13 @@ static void evsel__disable_missing_features(struct evsel *evsel)
> > >               evsel->open_flags &= ~(unsigned long)PERF_FLAG_FD_CLOEXEC;
> > >       if (perf_missing_features.mmap2)
> > >               evsel->core.attr.mmap2 = 0;
> > > -     if (perf_missing_features.exclude_guest)
> > > -             evsel->core.attr.exclude_guest = evsel->core.attr.exclude_host = 0;
> > > +     if (perf_missing_features.exclude_guest) {
> > > +             /* we only have EXCLUDE_GUEST bit, let's skip checking  */
> > > +             if (hashmap__find(perf_missing_features.pmu, evsel, NULL)) {
> > > +                     evsel->core.attr.exclude_guest = 0;
> > > +                     evsel->core.attr.exclude_host = 0;
> > > +             }
> > > +     }
> > >       if (perf_missing_features.lbr_flags)
> > >               evsel->core.attr.branch_sample_type &= ~(PERF_SAMPLE_BRANCH_NO_FLAGS |
> > >                                    PERF_SAMPLE_BRANCH_NO_CYCLES);
> > > @@ -1840,6 +1866,9 @@ int evsel__prepare_open(struct evsel *evsel, struct perf_cpu_map *cpus,
> > >
> > >  bool evsel__detect_missing_features(struct evsel *evsel)
> > >  {
> > > +     if (perf_missing_features.pmu == NULL)
> > > +             perf_missing_features.pmu = hashmap__new(pmu_hash, pmu_equal, NULL);
> >
> > missing allocation fail check
> 
> Ok, will change.
> 
> Thanks for your review,
> Namhyung
> 
> 
> >
> > > +
> > >       /*
> > >        * Must probe features in the order they were added to the
> > >        * perf_event_attr interface.
> > > @@ -1900,10 +1929,16 @@ bool evsel__detect_missing_features(struct evsel *evsel)
> > >               perf_missing_features.mmap2 = true;
> > >               pr_debug2_peo("switching off mmap2\n");
> > >               return true;
> > > -     } else if (!perf_missing_features.exclude_guest &&
> > > -                (evsel->core.attr.exclude_guest || evsel->core.attr.exclude_host)) {
> > > -             perf_missing_features.exclude_guest = true;
> > > -             pr_debug2_peo("switching off exclude_guest, exclude_host\n");
> > > +     } else if ((evsel->core.attr.exclude_guest || evsel->core.attr.exclude_host) &&
> > > +                !hashmap__find(perf_missing_features.pmu, evsel, NULL)) {
> > > +             uintptr_t pmu_features = PERF_MISSING_PMU_EXCLUDE_GUEST;
> > > +
> > > +             hashmap__add(perf_missing_features.pmu, evsel, (void *)pmu_features);
> > > +
> > > +             if (!perf_missing_features.exclude_guest) {
> > > +                     perf_missing_features.exclude_guest = true;
> > > +                     pr_debug2_peo("switching off exclude_guest, exclude_host\n");
> > > +             }
> > >               return true;
> > >       } else if (!perf_missing_features.sample_id_all) {
> > >               perf_missing_features.sample_id_all = true;
> > > diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h
> > > index 1f7edfa8568a..11b5ece19f0e 100644
> > > --- a/tools/perf/util/evsel.h
> > > +++ b/tools/perf/util/evsel.h
> > > @@ -172,6 +172,13 @@ struct perf_missing_features {
> > >       bool data_page_size;
> > >       bool code_page_size;
> > >       bool weight_struct;
> > > +
> > > +     /* contains enum perf_missing_pmu_features below */
> > > +     struct hashmap *pmu;
> > > +};
> > > +
> > > +enum perf_missing_pmu_features {
> > > +     PERF_MISSING_PMU_EXCLUDE_GUEST          = 1UL << 0,
> > >  };
> > >
> > >  extern struct perf_missing_features perf_missing_features;
> > > --
> > > 2.33.0.1079.g6e70778dc9-goog
> > >
> >
>