linux-kernel - Re: [PATCH v5 00/20] Introduce threaded trace streaming for basic perf record operation

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Message-ID: <CAM9d7cgqgF=771ATS-_25B=kyOfhM-6g5m086gOXyLaNR+cf9g@mail.gmail.com>
Date:   Thu, 6 May 2021 21:52:24 -0700
From:   Namhyung Kim <namhyung@...nel.org>
To:     Andi Kleen <ak@...ux.intel.com>
Cc:     Alexey Bayduraev <alexey.v.bayduraev@...ux.intel.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Jiri Olsa <jolsa@...hat.com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Alexander Antonov <alexander.antonov@...ux.intel.com>,
        Alexei Budankov <abudankov@...wei.com>
Subject: Re: [PATCH v5 00/20] Introduce threaded trace streaming for basic
 perf record operation

Hi Andi,

On Thu, May 6, 2021 at 7:17 AM Andi Kleen <ak@...ux.intel.com> wrote:
>
>
> On 5/5/2021 11:20 PM, Namhyung Kim wrote:
> >
> > Do you have an idea how to improve it?
> >
> > I have to say again that I don't like merely adding more threads to
> > record.  Yeah, parallelizing the perf record is good, but we have to
> > think about the perf report (and others) too.
>
> perf report/script can be already parallelized with --time xx/x% and a
> simple shell script that runs multiple processes. While that's a bit
> awkward for interactive use it works fine for scripting. I use it all
> the time for PT batch processing for example. The real bottleneck we
> have is really record on systems with many CPUs (which are more and more
> common), and that can only be fixed with some variant of this patch kit.

Right, spreading partial analysis to multiple processes would work
for some use cases.  I also agree that parallelizing perf record is
more important, but if there's a way to improve perf report/script
we should try that too.

Thanks,
Namhyung