From: Jiri Olsa <jolsa@redhat.com>
To: Ian Rogers <irogers@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Namhyung Kim <namhyung@kernel.org>,
Kan Liang <kan.liang@linux.intel.com>,
Adrian Hunter <adrian.hunter@intel.com>,
Alexey Budankov <alexey.budankov@linux.intel.com>,
yuzhoujian <yuzhoujian@didichuxing.com>,
Tony Jones <tonyj@suse.de>,
linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org,
Stephane Eranian <eranian@google.com>
Subject: Re: [PATCH v3] perf/record: add num-synthesize-threads option
Date: Thu, 23 Apr 2020 14:09:57 +0200 [thread overview]
Message-ID: <20200423120957.GL1136647@krava> (raw)
In-Reply-To: <20200422155038.9380-1-irogers@google.com>
On Wed, Apr 22, 2020 at 08:50:38AM -0700, Ian Rogers wrote:
> From: Stephane Eranian <eranian@google.com>
>
SNIP
> That is the processing is 1.49% of execution time and there is plenty to
> make parallel. This is shown in the benchmark in this patch:
> https://lore.kernel.org/lkml/20200415054050.31645-2-irogers@google.com/
> Computing performance of multi threaded perf event synthesis by
> synthesizing events on CPU 0:
> Number of synthesis threads: 1
> Average synthesis took: 127729.000 usec (+- 3372.880 usec)
> Average num. events: 21548.600 (+- 0.306)
> Average time per event 5.927 usec
> Number of synthesis threads: 2
> Average synthesis took: 88863.500 usec (+- 385.168 usec)
> Average num. events: 21552.800 (+- 0.327)
> Average time per event 4.123 usec
> Number of synthesis threads: 3
> Average synthesis took: 83257.400 usec (+- 348.617 usec)
> Average num. events: 21553.200 (+- 0.327)
> Average time per event 3.863 usec
> Number of synthesis threads: 4
> Average synthesis took: 75093.000 usec (+- 422.978 usec)
> Average num. events: 21554.200 (+- 0.200)
> Average time per event 3.484 usec
> Number of synthesis threads: 5
> Average synthesis took: 64896.600 usec (+- 353.348 usec)
> Average num. events: 21558.000 (+- 0.000)
> Average time per event 3.010 usec
> Number of synthesis threads: 6
> Average synthesis took: 59210.200 usec (+- 342.890 usec)
> Average num. events: 21560.000 (+- 0.000)
> Average time per event 2.746 usec
> Number of synthesis threads: 7
> Average synthesis took: 54093.900 usec (+- 306.247 usec)
> Average num. events: 21562.000 (+- 0.000)
> Average time per event 2.509 usec
> Number of synthesis threads: 8
> Average synthesis took: 48938.700 usec (+- 341.732 usec)
> Average num. events: 21564.000 (+- 0.000)
> Average time per event 2.269 usec
>
> Where average time per synthesized event goes from 5.927 usec with 1
> thread to 2.269 usec with 8. This isn't a linear speed up as not all of
> synthesize code has been made parallel. If the synthesis time was about
> 10 seconds then using 8 threads may bring this down to less than 4.
Acked-by: Jiri Olsa <jolsa@redhat.com>
thanks,
jirka
next prev parent reply other threads:[~2020-04-23 12:09 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-22 15:50 [PATCH v3] perf/record: add num-synthesize-threads option Ian Rogers
2020-04-23 12:09 ` Jiri Olsa [this message]
2020-04-23 14:11 ` Arnaldo Carvalho de Melo
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