Messages in this thread | | | From | Arnaldo Carvalho de Melo <> | Date | Thu, 23 Apr 2020 11:11:08 -0300 | Subject | Re: [PATCH v3] perf/record: add num-synthesize-threads option |
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Em Thu, Apr 23, 2020 at 02:09:57PM +0200, Jiri Olsa escreveu: > 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, applied.
- Arnaldo
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