Date: Mon, 14 Dec 2015 09:43:04 +0100
From: Jiri Olsa <jolsa@redhat.com>
To: Namhyung Kim <namhyung@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>, Ingo Molnar <mingo@kernel.org>,
        Peter Zijlstra <a.p.zijlstra@chello.nl>,
        LKML <linux-kernel@vger.kernel.org>, David Ahern <dsahern@gmail.com>,
        Frederic Weisbecker <fweisbec@gmail.com>,
        Andi Kleen <andi@firstfloor.org>,
        Stephane Eranian <eranian@google.com>,
        Adrian Hunter <adrian.hunter@intel.com>
Subject: Re: [PATCH/RFC 12/16] perf tools: Reduce lock contention when
 processing events
Message-ID: <20151214084303.GA17701@krava.brq.redhat.com>
References: <1449734015-9148-1-git-send-email-namhyung@kernel.org>
 <1449734015-9148-13-git-send-email-namhyung@kernel.org>
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On Thu, Dec 10, 2015 at 04:53:31PM +0900, Namhyung Kim wrote:
> When multi-thread is enabled, the machine->threads_lock is contented
> as all worker threads try to grab the writer lock using the
> machine__findnew_thread().  Usually, the thread they're looking for is
> in the tree so they only need the reader lock though.
> 
> Thus try machine__find_thread() first, and then fallback to the
> 'findnew' API.  This will improve the performance.

found one other place, but I guess you chose those
based on profiling the contention?

parent lookup in machine__process_fork_event

jirka
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