* [PATCH v4] perf evsel: Fix missing exclude_{host,guest} setting
@ 2021-11-05 20:58 Namhyung Kim
2021-11-06 19:09 ` Arnaldo Carvalho de Melo
0 siblings, 1 reply; 4+ messages in thread
From: Namhyung Kim @ 2021-11-05 20:58 UTC (permalink / raw)
To: Arnaldo Carvalho de Melo, Jiri Olsa
Cc: Ingo Molnar, Peter Zijlstra, LKML, Andi Kleen, Ian Rogers,
Stephane Eranian, Ravi Bangoria
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>
Cc: Ravi Bangoria <ravi.bangoria@amd.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
v4 changes)
* add pmu->missing_features.exclude_guest
* bail out if evsel->exclude_GH is set
v3 changes)
* check memory allocation failure
* add more NULL check
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 | 27 ++++++++++++++++++++++-----
tools/perf/util/evsel.h | 4 ++++
tools/perf/util/pmu.h | 4 ++++
3 files changed, 30 insertions(+), 5 deletions(-)
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index 2cfc2935d1d2..3cc1f8fcf15c 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -1824,7 +1824,7 @@ 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)
+ if (evsel->pmu && evsel->pmu->missing_features.exclude_guest)
evsel->core.attr.exclude_guest = evsel->core.attr.exclude_host = 0;
if (perf_missing_features.lbr_flags)
evsel->core.attr.branch_sample_type &= ~(PERF_SAMPLE_BRANCH_NO_FLAGS |
@@ -1917,10 +1917,27 @@ 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) &&
+ (evsel->pmu == NULL || evsel->pmu->missing_features.exclude_guest)) {
+ if (evsel->pmu == NULL) {
+ evsel->pmu = evsel__find_pmu(evsel);
+ if (evsel->pmu)
+ evsel->pmu->missing_features.exclude_guest = true;
+ else {
+ /* we cannot find PMU, disable attrs now */
+ evsel->core.attr.exclude_host = false;
+ evsel->core.attr.exclude_guest = false;
+ }
+ }
+
+ if (evsel->exclude_GH) {
+ pr_debug2_peo("PMU has no exclude_host/guest support, bailing out\n");
+ return false;
+ }
+ 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 846c827934de..dcc87c2881b8 100644
--- a/tools/perf/util/evsel.h
+++ b/tools/perf/util/evsel.h
@@ -22,6 +22,7 @@ struct target;
struct hashmap;
struct bperf_leader_bpf;
struct bperf_follower_bpf;
+struct perf_pmu;
typedef int (evsel__sb_cb_t)(union perf_event *event, void *data);
@@ -153,6 +154,9 @@ struct evsel {
};
unsigned long open_flags;
int precise_ip_original;
+
+ /* for missing_features */
+ struct perf_pmu *pmu;
};
struct perf_missing_features {
diff --git a/tools/perf/util/pmu.h b/tools/perf/util/pmu.h
index 15bbec3a9959..541889fa9f9c 100644
--- a/tools/perf/util/pmu.h
+++ b/tools/perf/util/pmu.h
@@ -49,6 +49,10 @@ struct perf_pmu {
struct list_head caps; /* HEAD struct perf_pmu_caps -> list */
struct list_head list; /* ELEM */
struct list_head hybrid_list;
+
+ struct {
+ bool exclude_guest;
+ } missing_features;
};
extern struct perf_pmu perf_pmu__fake;
--
2.34.0.rc0.344.g81b53c2807-goog
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH v4] perf evsel: Fix missing exclude_{host,guest} setting
2021-11-05 20:58 [PATCH v4] perf evsel: Fix missing exclude_{host,guest} setting Namhyung Kim
@ 2021-11-06 19:09 ` Arnaldo Carvalho de Melo
2021-11-06 19:19 ` Arnaldo Carvalho de Melo
2021-11-08 18:53 ` Namhyung Kim
0 siblings, 2 replies; 4+ messages in thread
From: Arnaldo Carvalho de Melo @ 2021-11-06 19:09 UTC (permalink / raw)
To: Namhyung Kim
Cc: Jiri Olsa, Ingo Molnar, Peter Zijlstra, LKML, Andi Kleen,
Ian Rogers, Stephane Eranian, Ravi Bangoria
Em Fri, Nov 05, 2021 at 01:58:47PM -0700, Namhyung Kim escreveu:
> 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.
⬢[acme@toolbox perf]$ perf test python
19: 'import perf' in python : FAILED!
⬢[acme@toolbox perf]$ perf test -v python
Couldn't bump rlimit(MEMLOCK), failures may take place when creating BPF maps, etc
19: 'import perf' in python :
--- start ---
test child forked, pid 11602
python usage test: "echo "import sys ; sys.path.append('/tmp/build/perf/python'); import perf" | '/usr/bin/python3' "
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ImportError: /tmp/build/perf/python/perf.cpython-39-x86_64-linux-gnu.so: undefined symbol: evsel__find_pmu
test child finished with -1
---- end ----
'import perf' in python: FAILED!
⬢[acme@toolbox perf]$
Trying to fix this now. please do a 'perf test' before submitting
patches.
- Arnaldo
> Reported-by: Stephane Eranian <eranian@google.com>
> Cc: Ravi Bangoria <ravi.bangoria@amd.com>
> Signed-off-by: Namhyung Kim <namhyung@kernel.org>
> ---
> v4 changes)
> * add pmu->missing_features.exclude_guest
> * bail out if evsel->exclude_GH is set
>
> v3 changes)
> * check memory allocation failure
> * add more NULL check
>
> 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 | 27 ++++++++++++++++++++++-----
> tools/perf/util/evsel.h | 4 ++++
> tools/perf/util/pmu.h | 4 ++++
> 3 files changed, 30 insertions(+), 5 deletions(-)
>
> diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
> index 2cfc2935d1d2..3cc1f8fcf15c 100644
> --- a/tools/perf/util/evsel.c
> +++ b/tools/perf/util/evsel.c
> @@ -1824,7 +1824,7 @@ 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)
> + if (evsel->pmu && evsel->pmu->missing_features.exclude_guest)
> evsel->core.attr.exclude_guest = evsel->core.attr.exclude_host = 0;
> if (perf_missing_features.lbr_flags)
> evsel->core.attr.branch_sample_type &= ~(PERF_SAMPLE_BRANCH_NO_FLAGS |
> @@ -1917,10 +1917,27 @@ 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) &&
> + (evsel->pmu == NULL || evsel->pmu->missing_features.exclude_guest)) {
> + if (evsel->pmu == NULL) {
> + evsel->pmu = evsel__find_pmu(evsel);
> + if (evsel->pmu)
> + evsel->pmu->missing_features.exclude_guest = true;
> + else {
> + /* we cannot find PMU, disable attrs now */
> + evsel->core.attr.exclude_host = false;
> + evsel->core.attr.exclude_guest = false;
> + }
> + }
> +
> + if (evsel->exclude_GH) {
> + pr_debug2_peo("PMU has no exclude_host/guest support, bailing out\n");
> + return false;
> + }
> + 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 846c827934de..dcc87c2881b8 100644
> --- a/tools/perf/util/evsel.h
> +++ b/tools/perf/util/evsel.h
> @@ -22,6 +22,7 @@ struct target;
> struct hashmap;
> struct bperf_leader_bpf;
> struct bperf_follower_bpf;
> +struct perf_pmu;
>
> typedef int (evsel__sb_cb_t)(union perf_event *event, void *data);
>
> @@ -153,6 +154,9 @@ struct evsel {
> };
> unsigned long open_flags;
> int precise_ip_original;
> +
> + /* for missing_features */
> + struct perf_pmu *pmu;
> };
>
> struct perf_missing_features {
> diff --git a/tools/perf/util/pmu.h b/tools/perf/util/pmu.h
> index 15bbec3a9959..541889fa9f9c 100644
> --- a/tools/perf/util/pmu.h
> +++ b/tools/perf/util/pmu.h
> @@ -49,6 +49,10 @@ struct perf_pmu {
> struct list_head caps; /* HEAD struct perf_pmu_caps -> list */
> struct list_head list; /* ELEM */
> struct list_head hybrid_list;
> +
> + struct {
> + bool exclude_guest;
> + } missing_features;
> };
>
> extern struct perf_pmu perf_pmu__fake;
> --
> 2.34.0.rc0.344.g81b53c2807-goog
--
- Arnaldo
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH v4] perf evsel: Fix missing exclude_{host,guest} setting
2021-11-06 19:09 ` Arnaldo Carvalho de Melo
@ 2021-11-06 19:19 ` Arnaldo Carvalho de Melo
2021-11-08 18:53 ` Namhyung Kim
1 sibling, 0 replies; 4+ messages in thread
From: Arnaldo Carvalho de Melo @ 2021-11-06 19:19 UTC (permalink / raw)
To: Namhyung Kim
Cc: Jiri Olsa, Ingo Molnar, Peter Zijlstra, LKML, Andi Kleen,
Ian Rogers, Stephane Eranian, Ravi Bangoria
Em Sat, Nov 06, 2021 at 04:09:49PM -0300, Arnaldo Carvalho de Melo escreveu:
> Em Fri, Nov 05, 2021 at 01:58:47PM -0700, Namhyung Kim escreveu:
> > 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.
>
> ⬢[acme@toolbox perf]$ perf test python
> 19: 'import perf' in python : FAILED!
> ⬢[acme@toolbox perf]$ perf test -v python
> Couldn't bump rlimit(MEMLOCK), failures may take place when creating BPF maps, etc
> 19: 'import perf' in python :
> --- start ---
> test child forked, pid 11602
> python usage test: "echo "import sys ; sys.path.append('/tmp/build/perf/python'); import perf" | '/usr/bin/python3' "
> Traceback (most recent call last):
> File "<stdin>", line 1, in <module>
> ImportError: /tmp/build/perf/python/perf.cpython-39-x86_64-linux-gnu.so: undefined symbol: evsel__find_pmu
> test child finished with -1
> ---- end ----
> 'import perf' in python: FAILED!
> ⬢[acme@toolbox perf]$
>
> Trying to fix this now. please do a 'perf test' before submitting
> patches.
Added this bandaid, should be good for the time being.
- Arnaldo
diff --git a/tools/perf/util/python.c b/tools/perf/util/python.c
index 8feef3a05af7b31d..563a9ba8954f31b3 100644
--- a/tools/perf/util/python.c
+++ b/tools/perf/util/python.c
@@ -69,6 +69,18 @@ void perf_stat__collect_metric_expr(struct evlist *evsel_list)
{
}
+/*
+ * This one is needed not to drag the PMU bandwagon, jevents generated
+ * pmu_sys_event_tables, etc and evsel__find_pmu() is used so far just for
+ * doing per PMU perf_event_attr.exclude_guest handling, not really needed, so
+ * far, for the perf python binding known usecases, revisit if this become
+ * necessary.
+ */
+struct perf_pmu *evsel__find_pmu(struct evsel *evsel __maybe_unused)
+{
+ return NULL;
+}
+
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH v4] perf evsel: Fix missing exclude_{host,guest} setting
2021-11-06 19:09 ` Arnaldo Carvalho de Melo
2021-11-06 19:19 ` Arnaldo Carvalho de Melo
@ 2021-11-08 18:53 ` Namhyung Kim
1 sibling, 0 replies; 4+ messages in thread
From: Namhyung Kim @ 2021-11-08 18:53 UTC (permalink / raw)
To: Arnaldo Carvalho de Melo
Cc: Jiri Olsa, Ingo Molnar, Peter Zijlstra, LKML, Andi Kleen,
Ian Rogers, Stephane Eranian, Ravi Bangoria
Hi Arnaldo,
On Sat, Nov 6, 2021 at 12:09 PM Arnaldo Carvalho de Melo
<acme@kernel.org> wrote:
>
> Em Fri, Nov 05, 2021 at 01:58:47PM -0700, Namhyung Kim escreveu:
> > 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.
>
> ⬢[acme@toolbox perf]$ perf test python
> 19: 'import perf' in python : FAILED!
> ⬢[acme@toolbox perf]$ perf test -v python
> Couldn't bump rlimit(MEMLOCK), failures may take place when creating BPF maps, etc
> 19: 'import perf' in python :
> --- start ---
> test child forked, pid 11602
> python usage test: "echo "import sys ; sys.path.append('/tmp/build/perf/python'); import perf" | '/usr/bin/python3' "
> Traceback (most recent call last):
> File "<stdin>", line 1, in <module>
> ImportError: /tmp/build/perf/python/perf.cpython-39-x86_64-linux-gnu.so: undefined symbol: evsel__find_pmu
> test child finished with -1
> ---- end ----
> 'import perf' in python: FAILED!
> ⬢[acme@toolbox perf]$
>
> Trying to fix this now. please do a 'perf test' before submitting
> patches.
Oops, sorry about that. Forgot to run it after the change.
I'll check it next time and thanks for the fix.
Thanks,
Namhyung
^ permalink raw reply [flat|nested] 4+ messages in thread
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2021-11-05 20:58 [PATCH v4] perf evsel: Fix missing exclude_{host,guest} setting Namhyung Kim
2021-11-06 19:09 ` Arnaldo Carvalho de Melo
2021-11-06 19:19 ` Arnaldo Carvalho de Melo
2021-11-08 18:53 ` Namhyung Kim
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