* duration_time regression
@ 2023-08-01 20:32 Andi Kleen
2023-08-01 21:47 ` Ian Rogers
0 siblings, 1 reply; 2+ messages in thread
From: Andi Kleen @ 2023-08-01 20:32 UTC (permalink / raw)
To: linux-perf-users; +Cc: irogers, acme, namhyung
With recent perf duration_time output regressed:
e.g. with an older version I get duration_time only once:
% perf stat -e cycles,duration_time true
CPU0 190,925 cycles
... all the other CPUs printing cycles
CPU0 5,047,008 ns duration_time
0.005047008 seconds time elapsed
with the current perf it is printed on all CPUs, but not counted on most
of them:
% perf stat -e cycles,duration_time true
# started on Tue Aug 1 13:29:26 2023
Performance counter stats for 'system wide':
CPU0 61,301 cycles
... print cycles for all CPUS ...
CPU0 5,343,556 ns duration_time
CPU1 <not counted> ns duration_time
CPU2 <not counted> ns duration_time
CPU3 <not counted> ns duration_time
CPU4 <not counted> ns duration_time
... repeat the same for all CPUs ...
which is fairly useless.
-Andi
^ permalink raw reply [flat|nested] 2+ messages in thread* Re: duration_time regression
2023-08-01 20:32 duration_time regression Andi Kleen
@ 2023-08-01 21:47 ` Ian Rogers
0 siblings, 0 replies; 2+ messages in thread
From: Ian Rogers @ 2023-08-01 21:47 UTC (permalink / raw)
To: Andi Kleen; +Cc: linux-perf-users, acme, namhyung
On Tue, Aug 1, 2023 at 1:32 PM Andi Kleen <ak@linux.intel.com> wrote:
>
>
> With recent perf duration_time output regressed:
>
> e.g. with an older version I get duration_time only once:
>
> % perf stat -e cycles,duration_time true
>
> CPU0 190,925 cycles
> ... all the other CPUs printing cycles
> CPU0 5,047,008 ns duration_time
>
> 0.005047008 seconds time elapsed
>
>
> with the current perf it is printed on all CPUs, but not counted on most
> of them:
>
> % perf stat -e cycles,duration_time true
>
> # started on Tue Aug 1 13:29:26 2023
>
> Performance counter stats for 'system wide':
>
> CPU0 61,301 cycles
> ... print cycles for all CPUS ...
> CPU0 5,343,556 ns duration_time
> CPU1 <not counted> ns duration_time
> CPU2 <not counted> ns duration_time
> CPU3 <not counted> ns duration_time
> CPU4 <not counted> ns duration_time
> ... repeat the same for all CPUs ...
>
> which is fairly useless.
Agreed, I sent out:
https://lore.kernel.org/lkml/20230801205452.3380578-1-irogers@google.com/
Thanks,
Ian
> -Andi
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