linux-kernel - Re: [PATCH v8 0/3]: perf: reduce data loss when profiling highly parallel CPU bound workloads

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Message-ID: <20180910100841.GB15548@krava>
Date:   Mon, 10 Sep 2018 12:08:41 +0200
From:   Jiri Olsa <jolsa@...hat.com>
To:     Ingo Molnar <mingo@...nel.org>
Cc:     Alexey Budankov <alexey.budankov@...ux.intel.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Andi Kleen <ak@...ux.intel.com>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v8 0/3]: perf: reduce data loss when profiling highly
 parallel CPU bound workloads

On Mon, Sep 10, 2018 at 12:03:03PM +0200, Ingo Molnar wrote:
> 
> * Jiri Olsa <jolsa@...hat.com> wrote:
> 
> > > Per-CPU threading the record session would have so many other advantages as well (scalability, 
> > > etc.).
> > > 
> > > Jiri did per-CPU recording patches a couple of months ago, not sure how usable they are at the 
> > > moment?
> > 
> > it's still usable, I can rebase it and post a branch pointer,
> > the problem is I haven't been able to find a case with a real
> > performance benefit yet.. ;-)
> > 
> > perhaps because I haven't tried on server with really big cpu
> > numbers
> 
> Maybe Alexey could pick up from there? Your concept looked fairly mature to me
> and I tried it on a big-CPU box back then and there were real improvements.

too bad u did not share your results, it could have been already in ;-)

let me rebase/repost once more and let's see

I think we could benefit from both multiple threads event reading
and AIO writing for perf.data.. it could be merged together

jirka