Re: [PATCH v2 0/3] perf tools: Minor improvements in event synthesis

[Namhyung Kim]

Hi Jiri,

On Mon, Feb 1, 2021 at 7:35 AM Jiri Olsa <jolsa@xxxxxxxxxx> wrote:
>
> On Fri, Jan 29, 2021 at 02:48:58PM +0900, Namhyung Kim wrote:
> > Hello,
> >
> > This is to optimize the event synthesis during perf record.
> >
> > The first patch is to reduce memory usage when many threads are used.
> > The second is to avoid unncessary syscalls for kernel threads.  And
> > the last one is to reduce the number of threads to iterate when new
> > threads are being created at the same time.
> >
> > Unfortunately there's no dramatic improvement here but I can see ~5%
> > gain in the 'perf bench internals synthesize' on a big machine.
> > (The numbers are not stable though)
> >
> >
> > Before:
> >   # perf bench internals synthesize --mt -M1 -I 100
> >   # Running 'internals/synthesize' benchmark:
> >   Computing performance of multi threaded perf event synthesis by
> >   synthesizing events on CPU 0:
> >     Number of synthesis threads: 1
> >       Average synthesis took: 68831.480 usec (+- 101.450 usec)
> >       Average num. events: 9982.000 (+- 0.000)
> >       Average time per event 6.896 usec
> >
> >
> > After:
> >   # perf bench internals synthesize --mt -M1 -I 100
> >   # Running 'internals/synthesize' benchmark:
> >   Computing performance of multi threaded perf event synthesis by
> >   synthesizing events on CPU 0:
> >     Number of synthesis threads: 1
> >       Average synthesis took: 65036.370 usec (+- 158.121 usec)
> >       Average num. events: 9982.000 (+- 0.000)
> >       Average time per event 6.515 usec
> >
> >
> > Thanks,
> > Namhyung
> >
> >
> > Namhyung Kim (3):
> >   perf tools: Use /proc/<PID>/task/<TID>/status for synthesis
> >   perf tools: Skip MMAP record synthesis for kernel threads
> >   perf tools: Use scandir() to iterate threads
>
> heya,
> is there any change to previous version?

No, it's just a rebase version.

Thanks,
Namhyung