linux-kernel - Re: [PATCH] perf inject: Flush ordered events on FINISHED

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Date:   Mon, 12 Oct 2020 14:04:48 +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 <a.p.zijlstra@...llo.nl>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Stephane Eranian <eranian@...gle.com>,
        Ian Rogers <irogers@...gle.com>,
        Al Grant <al.grant@...s.arm.com>,
        Adrian Hunter <adrian.hunter@...el.com>
Subject: Re: [PATCH] perf inject: Flush ordered events on FINISHED_ROUND

Hi Jiri,

On Thu, Oct 8, 2020 at 6:07 PM Jiri Olsa <jolsa@...hat.com> wrote:
>
> On Tue, Oct 06, 2020 at 02:40:32PM +0900, namhyung@...nel.org wrote:
> > This is the perf stat result:
> >
> > * Before
> >
> >      7,167,414,019      L1-dcache-loads
> >        337,471,761      L1-dcache-read-misses     #    4.71% of all L1-dcache hits
> >
> >       11.011224671 seconds time elapsed
> >
> >
> > * After
> >
> >      7,075,556,792      L1-dcache-loads
> >        771,810,388      L1-dcache-read-misses     #   10.91% of all L1-dcache hits
> >
> >       17.015901863 seconds time elapsed
> >
> >
> > Hmm.. it's a memory & time trade-off then.  Maybe we need a switch to
> > select which one?
>
> I'd keep the faster one ;-) so the one before

Yeah, it's hard to argue when it slows things down much.
But I'd like to note that memory consumption also can be a
big issue in some environments.  I'll bring this back later..

Thanks
Namhyung