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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAM9d7cjaUsDM13BsLBaQJyvXOGN-6B2VcKNpZJ+L8DD75jA3Wg@mail.gmail.com>
Date:   Mon, 1 Feb 2021 13:35:04 +0900
From:   Namhyung Kim <namhyung@...nel.org>
To:     Jiri Olsa <jolsa@...hat.com>
Cc:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Stephane Eranian <eranian@...gle.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Ian Rogers <irogers@...gle.com>
Subject: Re: [PATCH v2 0/3] perf tools: Minor improvements in event synthesis

Hi Jiri,

On Mon, Feb 1, 2021 at 7:35 AM Jiri Olsa <jolsa@...hat.com> 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