tools/perf/builtin-stat.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-)
If an event shows as "<not supported>" in perf stat output, in verbose
mode add the strerror output to help diagnose the issue.
Consider:
```
$ perf stat -e cycles,data_read,instructions true
Performance counter stats for 'true':
357,457 cycles:u
<not supported> MiB data_read:u
156,182 instructions:u # 0.44 insn per cycle
0.001250315 seconds time elapsed
0.001283000 seconds user
0.000000000 seconds sys
```
To understand why the data_read uncore event failed, with this change:
```
$ perf stat -v -e cycles,data_read,instructions true
Using CPUID GenuineIntel-6-8D-1
cycles -> cpu/cycles/
data_read -> uncore_imc_free_running_0/data_read/
data_read -> uncore_imc_free_running_1/data_read/
instructions -> cpu/instructions/
Control descriptor is not initialized
Warning:
kernel.perf_event_paranoid=2, trying to fall back to excluding kernel and hypervisor samples
Warning:
kernel.perf_event_paranoid=2, trying to fall back to excluding kernel and hypervisor samples
Warning:
kernel.perf_event_paranoid=2, trying to fall back to excluding kernel and hypervisor samples
Warning:
data_read:u event is not supported by the kernel.
Invalid event (data_read:u) in per-thread mode, enable system wide with '-a'.
Warning:
kernel.perf_event_paranoid=2, trying to fall back to excluding kernel and hypervisor samples
Warning:
data_read:u event is not supported by the kernel.
Invalid event (data_read:u) in per-thread mode, enable system wide with '-a'.
cycles:u: 351621 362833 362833
failed to read counter data_read:u
failed to read counter data_read:u
instructions:u: 156184 362833 362833
Performance counter stats for 'true':
351,621 cycles:u
<not supported> MiB data_read:u
156,184 instructions:u # 0.44 insn per cycle
0.001584472 seconds time elapsed
0.001811000 seconds user
0.000000000 seconds sys
```
where without this change only "data_read:u event is not supported by
the kernel." is shown.
Signed-off-by: Ian Rogers <irogers@google.com>
---
tools/perf/builtin-stat.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)
diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index 7006f848f87a..84e06ec09cc2 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -624,8 +624,9 @@ static enum counter_recovery stat_handle_error(struct evsel *counter, int err)
*/
if (err == EINVAL || err == ENOSYS || err == ENOENT || err == ENXIO) {
if (verbose > 0) {
- ui__warning("%s event is not supported by the kernel.\n",
- evsel__name(counter));
+ evsel__open_strerror(counter, &target, err, msg, sizeof(msg));
+ ui__warning("%s event is not supported by the kernel.\n%s\n",
+ evsel__name(counter), msg);
}
return COUNTER_SKIP;
}
@@ -649,10 +650,11 @@ static enum counter_recovery stat_handle_error(struct evsel *counter, int err)
}
}
if (verbose > 0) {
+ evsel__open_strerror(counter, &target, err, msg, sizeof(msg));
ui__warning(err == EOPNOTSUPP
- ? "%s event is not supported by the kernel.\n"
- : "skipping event %s that kernel failed to open.\n",
- evsel__name(counter));
+ ? "%s event is not supported by the kernel.\n%s\n"
+ : "skipping event %s that kernel failed to open.\n%s\n",
+ evsel__name(counter), msg);
}
return COUNTER_SKIP;
}
--
2.51.0.618.g983fd99d29-googOn Sun, Oct 05, 2025 at 11:14:21AM -0700, Ian Rogers wrote:
> If an event shows as "<not supported>" in perf stat output, in verbose
> mode add the strerror output to help diagnose the issue.
>
> Consider:
> ```
> $ perf stat -e cycles,data_read,instructions true
>
> Performance counter stats for 'true':
>
> 357,457 cycles:u
> <not supported> MiB data_read:u
> 156,182 instructions:u # 0.44 insn per cycle
>
> 0.001250315 seconds time elapsed
>
> 0.001283000 seconds user
> 0.000000000 seconds sys
> ```
>
> To understand why the data_read uncore event failed, with this change:
> ```
> $ perf stat -v -e cycles,data_read,instructions true
> Using CPUID GenuineIntel-6-8D-1
> cycles -> cpu/cycles/
> data_read -> uncore_imc_free_running_0/data_read/
> data_read -> uncore_imc_free_running_1/data_read/
> instructions -> cpu/instructions/
> Control descriptor is not initialized
> Warning:
> kernel.perf_event_paranoid=2, trying to fall back to excluding kernel and hypervisor samples
> Warning:
> kernel.perf_event_paranoid=2, trying to fall back to excluding kernel and hypervisor samples
> Warning:
> kernel.perf_event_paranoid=2, trying to fall back to excluding kernel and hypervisor samples
> Warning:
> data_read:u event is not supported by the kernel.
> Invalid event (data_read:u) in per-thread mode, enable system wide with '-a'.
> Warning:
> kernel.perf_event_paranoid=2, trying to fall back to excluding kernel and hypervisor samples
> Warning:
> data_read:u event is not supported by the kernel.
> Invalid event (data_read:u) in per-thread mode, enable system wide with '-a'.
> cycles:u: 351621 362833 362833
> failed to read counter data_read:u
> failed to read counter data_read:u
> instructions:u: 156184 362833 362833
>
> Performance counter stats for 'true':
>
> 351,621 cycles:u
> <not supported> MiB data_read:u
> 156,184 instructions:u # 0.44 insn per cycle
>
> 0.001584472 seconds time elapsed
>
> 0.001811000 seconds user
> 0.000000000 seconds sys
> ```
> where without this change only "data_read:u event is not supported by
> the kernel." is shown.
I think what you say is:
Before:
data_read:u event is not supported by the kernel.
After:
data_read:u event is not supported by the kernel.
Invalid event (data_read:u) in per-thread mode, enable system wide with '-a'.
Off-topic, it'd be great if we reduce the number of the same warning
messages. I think the data_read is from two uncore PMUs so the message
was repeated. If we can connect the related evsels and show the
messages once, then the output is more readable. Maybe we also want to
show the fallback message just once (globally).
Thanks,
Namhyung
>
> Signed-off-by: Ian Rogers <irogers@google.com>
> ---
> tools/perf/builtin-stat.c | 12 +++++++-----
> 1 file changed, 7 insertions(+), 5 deletions(-)
>
> diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
> index 7006f848f87a..84e06ec09cc2 100644
> --- a/tools/perf/builtin-stat.c
> +++ b/tools/perf/builtin-stat.c
> @@ -624,8 +624,9 @@ static enum counter_recovery stat_handle_error(struct evsel *counter, int err)
> */
> if (err == EINVAL || err == ENOSYS || err == ENOENT || err == ENXIO) {
> if (verbose > 0) {
> - ui__warning("%s event is not supported by the kernel.\n",
> - evsel__name(counter));
> + evsel__open_strerror(counter, &target, err, msg, sizeof(msg));
> + ui__warning("%s event is not supported by the kernel.\n%s\n",
> + evsel__name(counter), msg);
> }
> return COUNTER_SKIP;
> }
> @@ -649,10 +650,11 @@ static enum counter_recovery stat_handle_error(struct evsel *counter, int err)
> }
> }
> if (verbose > 0) {
> + evsel__open_strerror(counter, &target, err, msg, sizeof(msg));
> ui__warning(err == EOPNOTSUPP
> - ? "%s event is not supported by the kernel.\n"
> - : "skipping event %s that kernel failed to open.\n",
> - evsel__name(counter));
> + ? "%s event is not supported by the kernel.\n%s\n"
> + : "skipping event %s that kernel failed to open.\n%s\n",
> + evsel__name(counter), msg);
> }
> return COUNTER_SKIP;
> }
> --
> 2.51.0.618.g983fd99d29-goog
>
On Wed, Oct 8, 2025 at 1:43 AM Namhyung Kim <namhyung@kernel.org> wrote:
>
> On Sun, Oct 05, 2025 at 11:14:21AM -0700, Ian Rogers wrote:
> > If an event shows as "<not supported>" in perf stat output, in verbose
> > mode add the strerror output to help diagnose the issue.
> >
> > Consider:
> > ```
> > $ perf stat -e cycles,data_read,instructions true
> >
> > Performance counter stats for 'true':
> >
> > 357,457 cycles:u
> > <not supported> MiB data_read:u
> > 156,182 instructions:u # 0.44 insn per cycle
> >
> > 0.001250315 seconds time elapsed
> >
> > 0.001283000 seconds user
> > 0.000000000 seconds sys
> > ```
> >
> > To understand why the data_read uncore event failed, with this change:
> > ```
> > $ perf stat -v -e cycles,data_read,instructions true
> > Using CPUID GenuineIntel-6-8D-1
> > cycles -> cpu/cycles/
> > data_read -> uncore_imc_free_running_0/data_read/
> > data_read -> uncore_imc_free_running_1/data_read/
> > instructions -> cpu/instructions/
> > Control descriptor is not initialized
> > Warning:
> > kernel.perf_event_paranoid=2, trying to fall back to excluding kernel and hypervisor samples
> > Warning:
> > kernel.perf_event_paranoid=2, trying to fall back to excluding kernel and hypervisor samples
> > Warning:
> > kernel.perf_event_paranoid=2, trying to fall back to excluding kernel and hypervisor samples
> > Warning:
> > data_read:u event is not supported by the kernel.
> > Invalid event (data_read:u) in per-thread mode, enable system wide with '-a'.
> > Warning:
> > kernel.perf_event_paranoid=2, trying to fall back to excluding kernel and hypervisor samples
> > Warning:
> > data_read:u event is not supported by the kernel.
> > Invalid event (data_read:u) in per-thread mode, enable system wide with '-a'.
> > cycles:u: 351621 362833 362833
> > failed to read counter data_read:u
> > failed to read counter data_read:u
> > instructions:u: 156184 362833 362833
> >
> > Performance counter stats for 'true':
> >
> > 351,621 cycles:u
> > <not supported> MiB data_read:u
> > 156,184 instructions:u # 0.44 insn per cycle
> >
> > 0.001584472 seconds time elapsed
> >
> > 0.001811000 seconds user
> > 0.000000000 seconds sys
> > ```
> > where without this change only "data_read:u event is not supported by
> > the kernel." is shown.
>
> I think what you say is:
>
> Before:
> data_read:u event is not supported by the kernel.
>
> After:
> data_read:u event is not supported by the kernel.
> Invalid event (data_read:u) in per-thread mode, enable system wide with '-a'.
I kept things verbose as unfortunately the
"kernel.perf_event_paranoid=2" is important as is the use of
per-thread mode. Different paranoia levels lead to different errors
and unfortunately a lot of the time the error gets reported as "
data_read:u event is not supported by the kernel." and I'm not sure
all users will get that the key part there is the :u modifier.
However, fixing evsel__open_strerror wasn't in scope for this change.
Thanks,
Ian
> Off-topic, it'd be great if we reduce the number of the same warning
> messages. I think the data_read is from two uncore PMUs so the message
> was repeated. If we can connect the related evsels and show the
> messages once, then the output is more readable. Maybe we also want to
> show the fallback message just once (globally).
>
> Thanks,
> Namhyung
>
> >
> > Signed-off-by: Ian Rogers <irogers@google.com>
> > ---
> > tools/perf/builtin-stat.c | 12 +++++++-----
> > 1 file changed, 7 insertions(+), 5 deletions(-)
> >
> > diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
> > index 7006f848f87a..84e06ec09cc2 100644
> > --- a/tools/perf/builtin-stat.c
> > +++ b/tools/perf/builtin-stat.c
> > @@ -624,8 +624,9 @@ static enum counter_recovery stat_handle_error(struct evsel *counter, int err)
> > */
> > if (err == EINVAL || err == ENOSYS || err == ENOENT || err == ENXIO) {
> > if (verbose > 0) {
> > - ui__warning("%s event is not supported by the kernel.\n",
> > - evsel__name(counter));
> > + evsel__open_strerror(counter, &target, err, msg, sizeof(msg));
> > + ui__warning("%s event is not supported by the kernel.\n%s\n",
> > + evsel__name(counter), msg);
> > }
> > return COUNTER_SKIP;
> > }
> > @@ -649,10 +650,11 @@ static enum counter_recovery stat_handle_error(struct evsel *counter, int err)
> > }
> > }
> > if (verbose > 0) {
> > + evsel__open_strerror(counter, &target, err, msg, sizeof(msg));
> > ui__warning(err == EOPNOTSUPP
> > - ? "%s event is not supported by the kernel.\n"
> > - : "skipping event %s that kernel failed to open.\n",
> > - evsel__name(counter));
> > + ? "%s event is not supported by the kernel.\n%s\n"
> > + : "skipping event %s that kernel failed to open.\n%s\n",
> > + evsel__name(counter), msg);
> > }
> > return COUNTER_SKIP;
> > }
> > --
> > 2.51.0.618.g983fd99d29-goog
> >
On Wed, Oct 08, 2025 at 09:31:53AM -0700, Ian Rogers wrote:
> On Wed, Oct 8, 2025 at 1:43 AM Namhyung Kim <namhyung@kernel.org> wrote:
> >
> > On Sun, Oct 05, 2025 at 11:14:21AM -0700, Ian Rogers wrote:
> > > If an event shows as "<not supported>" in perf stat output, in verbose
> > > mode add the strerror output to help diagnose the issue.
> > >
> > > Consider:
> > > ```
> > > $ perf stat -e cycles,data_read,instructions true
> > >
> > > Performance counter stats for 'true':
> > >
> > > 357,457 cycles:u
> > > <not supported> MiB data_read:u
> > > 156,182 instructions:u # 0.44 insn per cycle
> > >
> > > 0.001250315 seconds time elapsed
> > >
> > > 0.001283000 seconds user
> > > 0.000000000 seconds sys
> > > ```
> > >
> > > To understand why the data_read uncore event failed, with this change:
> > > ```
> > > $ perf stat -v -e cycles,data_read,instructions true
> > > Using CPUID GenuineIntel-6-8D-1
> > > cycles -> cpu/cycles/
> > > data_read -> uncore_imc_free_running_0/data_read/
> > > data_read -> uncore_imc_free_running_1/data_read/
> > > instructions -> cpu/instructions/
> > > Control descriptor is not initialized
> > > Warning:
> > > kernel.perf_event_paranoid=2, trying to fall back to excluding kernel and hypervisor samples
> > > Warning:
> > > kernel.perf_event_paranoid=2, trying to fall back to excluding kernel and hypervisor samples
> > > Warning:
> > > kernel.perf_event_paranoid=2, trying to fall back to excluding kernel and hypervisor samples
> > > Warning:
> > > data_read:u event is not supported by the kernel.
> > > Invalid event (data_read:u) in per-thread mode, enable system wide with '-a'.
> > > Warning:
> > > kernel.perf_event_paranoid=2, trying to fall back to excluding kernel and hypervisor samples
> > > Warning:
> > > data_read:u event is not supported by the kernel.
> > > Invalid event (data_read:u) in per-thread mode, enable system wide with '-a'.
> > > cycles:u: 351621 362833 362833
> > > failed to read counter data_read:u
> > > failed to read counter data_read:u
> > > instructions:u: 156184 362833 362833
> > >
> > > Performance counter stats for 'true':
> > >
> > > 351,621 cycles:u
> > > <not supported> MiB data_read:u
> > > 156,184 instructions:u # 0.44 insn per cycle
> > >
> > > 0.001584472 seconds time elapsed
> > >
> > > 0.001811000 seconds user
> > > 0.000000000 seconds sys
> > > ```
> > > where without this change only "data_read:u event is not supported by
> > > the kernel." is shown.
> >
> > I think what you say is:
> >
> > Before:
> > data_read:u event is not supported by the kernel.
> >
> > After:
> > data_read:u event is not supported by the kernel.
> > Invalid event (data_read:u) in per-thread mode, enable system wide with '-a'.
>
> I kept things verbose as unfortunately the
> "kernel.perf_event_paranoid=2" is important as is the use of
> per-thread mode. Different paranoia levels lead to different errors
> and unfortunately a lot of the time the error gets reported as "
> data_read:u event is not supported by the kernel." and I'm not sure
> all users will get that the key part there is the :u modifier.
Yep, I'm ok with the change. But the changelog was a bit unclear what
is being added exactly. IIUC we already have the paranoid message with
the verbose level 1.
> However, fixing evsel__open_strerror wasn't in scope for this change.
Sure, we can handle that separately.
Thanks,
Namhyung
>
> > Off-topic, it'd be great if we reduce the number of the same warning
> > messages. I think the data_read is from two uncore PMUs so the message
> > was repeated. If we can connect the related evsels and show the
> > messages once, then the output is more readable. Maybe we also want to
> > show the fallback message just once (globally).
> >
> > Thanks,
> > Namhyung
> >
> > >
> > > Signed-off-by: Ian Rogers <irogers@google.com>
> > > ---
> > > tools/perf/builtin-stat.c | 12 +++++++-----
> > > 1 file changed, 7 insertions(+), 5 deletions(-)
> > >
> > > diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
> > > index 7006f848f87a..84e06ec09cc2 100644
> > > --- a/tools/perf/builtin-stat.c
> > > +++ b/tools/perf/builtin-stat.c
> > > @@ -624,8 +624,9 @@ static enum counter_recovery stat_handle_error(struct evsel *counter, int err)
> > > */
> > > if (err == EINVAL || err == ENOSYS || err == ENOENT || err == ENXIO) {
> > > if (verbose > 0) {
> > > - ui__warning("%s event is not supported by the kernel.\n",
> > > - evsel__name(counter));
> > > + evsel__open_strerror(counter, &target, err, msg, sizeof(msg));
> > > + ui__warning("%s event is not supported by the kernel.\n%s\n",
> > > + evsel__name(counter), msg);
> > > }
> > > return COUNTER_SKIP;
> > > }
> > > @@ -649,10 +650,11 @@ static enum counter_recovery stat_handle_error(struct evsel *counter, int err)
> > > }
> > > }
> > > if (verbose > 0) {
> > > + evsel__open_strerror(counter, &target, err, msg, sizeof(msg));
> > > ui__warning(err == EOPNOTSUPP
> > > - ? "%s event is not supported by the kernel.\n"
> > > - : "skipping event %s that kernel failed to open.\n",
> > > - evsel__name(counter));
> > > + ? "%s event is not supported by the kernel.\n%s\n"
> > > + : "skipping event %s that kernel failed to open.\n%s\n",
> > > + evsel__name(counter), msg);
> > > }
> > > return COUNTER_SKIP;
> > > }
> > > --
> > > 2.51.0.618.g983fd99d29-goog
> > >
On Wed, Oct 8, 2025 at 10:51 PM Namhyung Kim <namhyung@kernel.org> wrote:
>
> On Wed, Oct 08, 2025 at 09:31:53AM -0700, Ian Rogers wrote:
> > On Wed, Oct 8, 2025 at 1:43 AM Namhyung Kim <namhyung@kernel.org> wrote:
> > >
> > > On Sun, Oct 05, 2025 at 11:14:21AM -0700, Ian Rogers wrote:
> > > > If an event shows as "<not supported>" in perf stat output, in verbose
> > > > mode add the strerror output to help diagnose the issue.
> > > >
> > > > Consider:
> > > > ```
> > > > $ perf stat -e cycles,data_read,instructions true
> > > >
> > > > Performance counter stats for 'true':
> > > >
> > > > 357,457 cycles:u
> > > > <not supported> MiB data_read:u
> > > > 156,182 instructions:u # 0.44 insn per cycle
> > > >
> > > > 0.001250315 seconds time elapsed
> > > >
> > > > 0.001283000 seconds user
> > > > 0.000000000 seconds sys
> > > > ```
> > > >
> > > > To understand why the data_read uncore event failed, with this change:
> > > > ```
> > > > $ perf stat -v -e cycles,data_read,instructions true
> > > > Using CPUID GenuineIntel-6-8D-1
> > > > cycles -> cpu/cycles/
> > > > data_read -> uncore_imc_free_running_0/data_read/
> > > > data_read -> uncore_imc_free_running_1/data_read/
> > > > instructions -> cpu/instructions/
> > > > Control descriptor is not initialized
> > > > Warning:
> > > > kernel.perf_event_paranoid=2, trying to fall back to excluding kernel and hypervisor samples
> > > > Warning:
> > > > kernel.perf_event_paranoid=2, trying to fall back to excluding kernel and hypervisor samples
> > > > Warning:
> > > > kernel.perf_event_paranoid=2, trying to fall back to excluding kernel and hypervisor samples
> > > > Warning:
> > > > data_read:u event is not supported by the kernel.
> > > > Invalid event (data_read:u) in per-thread mode, enable system wide with '-a'.
> > > > Warning:
> > > > kernel.perf_event_paranoid=2, trying to fall back to excluding kernel and hypervisor samples
> > > > Warning:
> > > > data_read:u event is not supported by the kernel.
> > > > Invalid event (data_read:u) in per-thread mode, enable system wide with '-a'.
> > > > cycles:u: 351621 362833 362833
> > > > failed to read counter data_read:u
> > > > failed to read counter data_read:u
> > > > instructions:u: 156184 362833 362833
> > > >
> > > > Performance counter stats for 'true':
> > > >
> > > > 351,621 cycles:u
> > > > <not supported> MiB data_read:u
> > > > 156,184 instructions:u # 0.44 insn per cycle
> > > >
> > > > 0.001584472 seconds time elapsed
> > > >
> > > > 0.001811000 seconds user
> > > > 0.000000000 seconds sys
> > > > ```
> > > > where without this change only "data_read:u event is not supported by
> > > > the kernel." is shown.
> > >
> > > I think what you say is:
> > >
> > > Before:
> > > data_read:u event is not supported by the kernel.
> > >
> > > After:
> > > data_read:u event is not supported by the kernel.
> > > Invalid event (data_read:u) in per-thread mode, enable system wide with '-a'.
> >
> > I kept things verbose as unfortunately the
> > "kernel.perf_event_paranoid=2" is important as is the use of
> > per-thread mode. Different paranoia levels lead to different errors
> > and unfortunately a lot of the time the error gets reported as "
> > data_read:u event is not supported by the kernel." and I'm not sure
> > all users will get that the key part there is the :u modifier.
>
> Yep, I'm ok with the change. But the changelog was a bit unclear what
> is being added exactly. IIUC we already have the paranoid message with
> the verbose level 1.
I thought the line:
"""
where without this change only "data_read:u event is not supported by
the kernel." is shown.
"""
covered this?
Thanks,
Ian
> > However, fixing evsel__open_strerror wasn't in scope for this change.
>
> Sure, we can handle that separately.
>
> Thanks,
> Namhyung
>
> >
> > > Off-topic, it'd be great if we reduce the number of the same warning
> > > messages. I think the data_read is from two uncore PMUs so the message
> > > was repeated. If we can connect the related evsels and show the
> > > messages once, then the output is more readable. Maybe we also want to
> > > show the fallback message just once (globally).
> > >
> > > Thanks,
> > > Namhyung
> > >
> > > >
> > > > Signed-off-by: Ian Rogers <irogers@google.com>
> > > > ---
> > > > tools/perf/builtin-stat.c | 12 +++++++-----
> > > > 1 file changed, 7 insertions(+), 5 deletions(-)
> > > >
> > > > diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
> > > > index 7006f848f87a..84e06ec09cc2 100644
> > > > --- a/tools/perf/builtin-stat.c
> > > > +++ b/tools/perf/builtin-stat.c
> > > > @@ -624,8 +624,9 @@ static enum counter_recovery stat_handle_error(struct evsel *counter, int err)
> > > > */
> > > > if (err == EINVAL || err == ENOSYS || err == ENOENT || err == ENXIO) {
> > > > if (verbose > 0) {
> > > > - ui__warning("%s event is not supported by the kernel.\n",
> > > > - evsel__name(counter));
> > > > + evsel__open_strerror(counter, &target, err, msg, sizeof(msg));
> > > > + ui__warning("%s event is not supported by the kernel.\n%s\n",
> > > > + evsel__name(counter), msg);
> > > > }
> > > > return COUNTER_SKIP;
> > > > }
> > > > @@ -649,10 +650,11 @@ static enum counter_recovery stat_handle_error(struct evsel *counter, int err)
> > > > }
> > > > }
> > > > if (verbose > 0) {
> > > > + evsel__open_strerror(counter, &target, err, msg, sizeof(msg));
> > > > ui__warning(err == EOPNOTSUPP
> > > > - ? "%s event is not supported by the kernel.\n"
> > > > - : "skipping event %s that kernel failed to open.\n",
> > > > - evsel__name(counter));
> > > > + ? "%s event is not supported by the kernel.\n%s\n"
> > > > + : "skipping event %s that kernel failed to open.\n%s\n",
> > > > + evsel__name(counter), msg);
> > > > }
> > > > return COUNTER_SKIP;
> > > > }
> > > > --
> > > > 2.51.0.618.g983fd99d29-goog
> > > >
On Thu, Oct 09, 2025 at 06:31:51AM -0700, Ian Rogers wrote: > On Wed, Oct 8, 2025 at 10:51 PM Namhyung Kim <namhyung@kernel.org> wrote: > > > > On Wed, Oct 08, 2025 at 09:31:53AM -0700, Ian Rogers wrote: > > > On Wed, Oct 8, 2025 at 1:43 AM Namhyung Kim <namhyung@kernel.org> wrote: > > > > > > > > On Sun, Oct 05, 2025 at 11:14:21AM -0700, Ian Rogers wrote: > > > > > If an event shows as "<not supported>" in perf stat output, in verbose > > > > > mode add the strerror output to help diagnose the issue. > > > > > > > > > > Consider: > > > > > ``` > > > > > $ perf stat -e cycles,data_read,instructions true > > > > > > > > > > Performance counter stats for 'true': > > > > > > > > > > 357,457 cycles:u > > > > > <not supported> MiB data_read:u > > > > > 156,182 instructions:u # 0.44 insn per cycle > > > > > > > > > > 0.001250315 seconds time elapsed > > > > > > > > > > 0.001283000 seconds user > > > > > 0.000000000 seconds sys > > > > > ``` > > > > > > > > > > To understand why the data_read uncore event failed, with this change: > > > > > ``` > > > > > $ perf stat -v -e cycles,data_read,instructions true > > > > > Using CPUID GenuineIntel-6-8D-1 > > > > > cycles -> cpu/cycles/ > > > > > data_read -> uncore_imc_free_running_0/data_read/ > > > > > data_read -> uncore_imc_free_running_1/data_read/ > > > > > instructions -> cpu/instructions/ > > > > > Control descriptor is not initialized > > > > > Warning: > > > > > kernel.perf_event_paranoid=2, trying to fall back to excluding kernel and hypervisor samples > > > > > Warning: > > > > > kernel.perf_event_paranoid=2, trying to fall back to excluding kernel and hypervisor samples > > > > > Warning: > > > > > kernel.perf_event_paranoid=2, trying to fall back to excluding kernel and hypervisor samples > > > > > Warning: > > > > > data_read:u event is not supported by the kernel. > > > > > Invalid event (data_read:u) in per-thread mode, enable system wide with '-a'. > > > > > Warning: > > > > > kernel.perf_event_paranoid=2, trying to fall back to excluding kernel and hypervisor samples > > > > > Warning: > > > > > data_read:u event is not supported by the kernel. > > > > > Invalid event (data_read:u) in per-thread mode, enable system wide with '-a'. > > > > > cycles:u: 351621 362833 362833 > > > > > failed to read counter data_read:u > > > > > failed to read counter data_read:u > > > > > instructions:u: 156184 362833 362833 > > > > > > > > > > Performance counter stats for 'true': > > > > > > > > > > 351,621 cycles:u > > > > > <not supported> MiB data_read:u > > > > > 156,184 instructions:u # 0.44 insn per cycle > > > > > > > > > > 0.001584472 seconds time elapsed > > > > > > > > > > 0.001811000 seconds user > > > > > 0.000000000 seconds sys > > > > > ``` > > > > > where without this change only "data_read:u event is not supported by > > > > > the kernel." is shown. > > > > > > > > I think what you say is: > > > > > > > > Before: > > > > data_read:u event is not supported by the kernel. > > > > > > > > After: > > > > data_read:u event is not supported by the kernel. > > > > Invalid event (data_read:u) in per-thread mode, enable system wide with '-a'. > > > > > > I kept things verbose as unfortunately the > > > "kernel.perf_event_paranoid=2" is important as is the use of > > > per-thread mode. Different paranoia levels lead to different errors > > > and unfortunately a lot of the time the error gets reported as " > > > data_read:u event is not supported by the kernel." and I'm not sure > > > all users will get that the key part there is the :u modifier. > > > > Yep, I'm ok with the change. But the changelog was a bit unclear what > > is being added exactly. IIUC we already have the paranoid message with > > the verbose level 1. > > I thought the line: > """ > where without this change only "data_read:u event is not supported by > the kernel." is shown. > """ > covered this? Yep, I've updated the commit log a little bit and applied to perf-tools-next. Thanks, Namhyung
© 2016 - 2025 Red Hat, Inc.