[PATCH] perf stat: Fix the hard-coded metrics calculation on the hybrid

[PATCH] perf stat: Fix the hard-coded metrics calculation on the hybrid

[kan.liang]

From: Kan Liang <kan.liang@linux.intel.com>

The hard-coded metrics is wrongly calculated on the hybrid machine.

$ perf stat -e cycles,instructions -a sleep 1

 Performance counter stats for 'system wide':

        18,205,487      cpu_atom/cycles/
         9,733,603      cpu_core/cycles/
         9,423,111      cpu_atom/instructions/     #  0.52  insn per cycle
         4,268,965      cpu_core/instructions/     #  0.23  insn per cycle

The insn per cycle for cpu_core should be 4,268,965 / 9,733,603 = 0.44.

When finding the metric events, the find_stat() doesn't take the PMU
type into account. The cpu_atom/cycles/ is wrongly used to calculate
the IPC of the cpu_core.

Fixes: 0a57b910807a ("perf stat: Use counts rather than saved_value")
Reported-by: "Khalil, Amiri" <amiri.khalil@intel.com>
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Cc: stable@vger.kernel.org
---
 tools/perf/util/stat-shadow.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/tools/perf/util/stat-shadow.c b/tools/perf/util/stat-shadow.c
index 3466aa952442..4d0edc061f1a 100644
--- a/tools/perf/util/stat-shadow.c
+++ b/tools/perf/util/stat-shadow.c
@@ -176,6 +176,10 @@ static double find_stat(const struct evsel *evsel, int aggr_idx, enum stat_type
 		if (type != evsel__stat_type(cur))
 			continue;
 
+		/* Ignore if not the PMU we're looking for. */
+		if (evsel->pmu != cur->pmu)
+			continue;
+
 		aggr = &cur->stats->aggr[aggr_idx];
 		if (type == STAT_NSECS)
 			return aggr->counts.val;
-- 
2.35.1

Re: [PATCH] perf stat: Fix the hard-coded metrics calculation on the hybrid

[Ian Rogers]

On Wed, Jun 5, 2024 at 9:10 AM <kan.liang@linux.intel.com> wrote:
>
> From: Kan Liang <kan.liang@linux.intel.com>
>
> The hard-coded metrics is wrongly calculated on the hybrid machine.
>
> $ perf stat -e cycles,instructions -a sleep 1
>
>  Performance counter stats for 'system wide':
>
>         18,205,487      cpu_atom/cycles/
>          9,733,603      cpu_core/cycles/
>          9,423,111      cpu_atom/instructions/     #  0.52  insn per cycle
>          4,268,965      cpu_core/instructions/     #  0.23  insn per cycle
>
> The insn per cycle for cpu_core should be 4,268,965 / 9,733,603 = 0.44.
>
> When finding the metric events, the find_stat() doesn't take the PMU
> type into account. The cpu_atom/cycles/ is wrongly used to calculate
> the IPC of the cpu_core.
>
> Fixes: 0a57b910807a ("perf stat: Use counts rather than saved_value")
> Reported-by: "Khalil, Amiri" <amiri.khalil@intel.com>
> Signed-off-by: Kan Liang <kan.liang@linux.intel.com>

Reviewed-by: Ian Rogers <irogers@google.com>

Thanks,
Ian

> Cc: stable@vger.kernel.org
> ---
>  tools/perf/util/stat-shadow.c | 4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/tools/perf/util/stat-shadow.c b/tools/perf/util/stat-shadow.c
> index 3466aa952442..4d0edc061f1a 100644
> --- a/tools/perf/util/stat-shadow.c
> +++ b/tools/perf/util/stat-shadow.c
> @@ -176,6 +176,10 @@ static double find_stat(const struct evsel *evsel, int aggr_idx, enum stat_type
>                 if (type != evsel__stat_type(cur))
>                         continue;
>
> +               /* Ignore if not the PMU we're looking for. */
> +               if (evsel->pmu != cur->pmu)
> +                       continue;
> +
>                 aggr = &cur->stats->aggr[aggr_idx];
>                 if (type == STAT_NSECS)
>                         return aggr->counts.val;
> --
> 2.35.1
>

Re: [PATCH] perf stat: Fix the hard-coded metrics calculation on the hybrid

[Namhyung Kim]

On Wed, Jun 5, 2024 at 10:21 AM Ian Rogers <irogers@google.com> wrote:
>
> On Wed, Jun 5, 2024 at 9:10 AM <kan.liang@linux.intel.com> wrote:
> >
> > From: Kan Liang <kan.liang@linux.intel.com>
> >
> > The hard-coded metrics is wrongly calculated on the hybrid machine.
> >
> > $ perf stat -e cycles,instructions -a sleep 1
> >
> >  Performance counter stats for 'system wide':
> >
> >         18,205,487      cpu_atom/cycles/
> >          9,733,603      cpu_core/cycles/
> >          9,423,111      cpu_atom/instructions/     #  0.52  insn per cycle
> >          4,268,965      cpu_core/instructions/     #  0.23  insn per cycle
> >
> > The insn per cycle for cpu_core should be 4,268,965 / 9,733,603 = 0.44.
> >
> > When finding the metric events, the find_stat() doesn't take the PMU
> > type into account. The cpu_atom/cycles/ is wrongly used to calculate
> > the IPC of the cpu_core.
> >
> > Fixes: 0a57b910807a ("perf stat: Use counts rather than saved_value")
> > Reported-by: "Khalil, Amiri" <amiri.khalil@intel.com>
> > Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
>
> Reviewed-by: Ian Rogers <irogers@google.com>
>
> Thanks,
> Ian
>
> > Cc: stable@vger.kernel.org
> > ---
> >  tools/perf/util/stat-shadow.c | 4 ++++
> >  1 file changed, 4 insertions(+)
> >
> > diff --git a/tools/perf/util/stat-shadow.c b/tools/perf/util/stat-shadow.c
> > index 3466aa952442..4d0edc061f1a 100644
> > --- a/tools/perf/util/stat-shadow.c
> > +++ b/tools/perf/util/stat-shadow.c
> > @@ -176,6 +176,10 @@ static double find_stat(const struct evsel *evsel, int aggr_idx, enum stat_type
> >                 if (type != evsel__stat_type(cur))
> >                         continue;
> >
> > +               /* Ignore if not the PMU we're looking for. */
> > +               if (evsel->pmu != cur->pmu)
> > +                       continue;

Hmm.. Don't some metrics need events from different PMU?
Like cycles per sec or branch instructions per sec..

Thanks,
Namhyung


> > +
> >                 aggr = &cur->stats->aggr[aggr_idx];
> >                 if (type == STAT_NSECS)
> >                         return aggr->counts.val;
> > --
> > 2.35.1
> >

Re: [PATCH] perf stat: Fix the hard-coded metrics calculation on the hybrid

[Liang, Kan]

On 2024-06-06 3:34 a.m., Namhyung Kim wrote:
> On Wed, Jun 5, 2024 at 10:21 AM Ian Rogers <irogers@google.com> wrote:
>>
>> On Wed, Jun 5, 2024 at 9:10 AM <kan.liang@linux.intel.com> wrote:
>>>
>>> From: Kan Liang <kan.liang@linux.intel.com>
>>>
>>> The hard-coded metrics is wrongly calculated on the hybrid machine.
>>>
>>> $ perf stat -e cycles,instructions -a sleep 1
>>>
>>>  Performance counter stats for 'system wide':
>>>
>>>         18,205,487      cpu_atom/cycles/
>>>          9,733,603      cpu_core/cycles/
>>>          9,423,111      cpu_atom/instructions/     #  0.52  insn per cycle
>>>          4,268,965      cpu_core/instructions/     #  0.23  insn per cycle
>>>
>>> The insn per cycle for cpu_core should be 4,268,965 / 9,733,603 = 0.44.
>>>
>>> When finding the metric events, the find_stat() doesn't take the PMU
>>> type into account. The cpu_atom/cycles/ is wrongly used to calculate
>>> the IPC of the cpu_core.
>>>
>>> Fixes: 0a57b910807a ("perf stat: Use counts rather than saved_value")
>>> Reported-by: "Khalil, Amiri" <amiri.khalil@intel.com>
>>> Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
>>
>> Reviewed-by: Ian Rogers <irogers@google.com>
>>
>> Thanks,
>> Ian
>>
>>> Cc: stable@vger.kernel.org
>>> ---
>>>  tools/perf/util/stat-shadow.c | 4 ++++
>>>  1 file changed, 4 insertions(+)
>>>
>>> diff --git a/tools/perf/util/stat-shadow.c b/tools/perf/util/stat-shadow.c
>>> index 3466aa952442..4d0edc061f1a 100644
>>> --- a/tools/perf/util/stat-shadow.c
>>> +++ b/tools/perf/util/stat-shadow.c
>>> @@ -176,6 +176,10 @@ static double find_stat(const struct evsel *evsel, int aggr_idx, enum stat_type
>>>                 if (type != evsel__stat_type(cur))
>>>                         continue;
>>>
>>> +               /* Ignore if not the PMU we're looking for. */
>>> +               if (evsel->pmu != cur->pmu)
>>> +                       continue;
> 
> Hmm.. Don't some metrics need events from different PMU?
> Like cycles per sec or branch instructions per sec..
>

Right.

In the hard-coded metrics, the events from a different PMU are
SW_CPU_CLOCK and SW_TASK_CLOCK. They both have the stat type,
STAT_NSECS. Perf should ignore the PMU checking for the type as below.
I will send a V2 to fix it.

diff --git a/tools/perf/util/stat-shadow.c b/tools/perf/util/stat-shadow.c
index 3466aa952442..d01335f18808 100644
--- a/tools/perf/util/stat-shadow.c
+++ b/tools/perf/util/stat-shadow.c
@@ -176,6 +176,9 @@ static double find_stat(const struct evsel *evsel,
int aggr_idx, enum stat_type
		if (type != evsel__stat_type(cur))
			continue;

+		if ((type != STAT_NSECS) && (evsel->pmu != cur->pmu))
+			continue;
+
		aggr = &cur->stats->aggr[aggr_idx];
		if (type == STAT_NSECS)
			return aggr->counts.val;


Thanks,
Kan

> Thanks,
> Namhyung
> 
> 
>>> +
>>>                 aggr = &cur->stats->aggr[aggr_idx];
>>>                 if (type == STAT_NSECS)
>>>                         return aggr->counts.val;
>>> --
>>> 2.35.1
>>>
>