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From: Andi Kleen <ak@linux.intel.com>
To: linux-perf-users@vger.kernel.org
Cc: irogers@google.com, acme@kernel.org, namhyung@kernel.org
Subject: duration_time regression
Date: Tue, 1 Aug 2023 13:32:13 -0700	[thread overview]
Message-ID: <ZMlrzcVrVi1lTDmn@tassilo> (raw)


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

             reply	other threads:[~2023-08-01 20:32 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-08-01 20:32 Andi Kleen [this message]
2023-08-01 21:47 ` duration_time regression Ian Rogers

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