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

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Message-ID: <20210312150933.GN203350@tassilo.jf.intel.com>
Date:   Fri, 12 Mar 2021 07:09:33 -0800
From:   Andi Kleen <ak@...ux.intel.com>
To:     Namhyung Kim <namhyung@...nel.org>
Cc:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Jiri Olsa <jolsa@...hat.com>, 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>,
        Ian Rogers <irogers@...gle.com>
Subject: Re: [PATCH 0/3] perf tools: Minor improvements in event synthesis

On Mon, Dec 21, 2020 at 04:00:26PM +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)

Looks all good to me. The VmPeak assumption might be slightly
fragile, but I guess there's nothing better currently.

Reviewed-by: Andi Kleen <ak@...ux.intel.com>

-Andi