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Date: Thu, 7 Jun 2018 08:45:22 -0700
From: Andi Kleen <andi@firstfloor.org>
To: Jiri Olsa <jolsa@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>,
        Peter Zijlstra <a.p.zijlstra@chello.nl>,
        lkml <linux-kernel@vger.kernel.org>,
        Ingo Molnar <mingo@kernel.org>,
        Namhyung Kim <namhyung@kernel.org>,
        David Ahern <dsahern@gmail.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Stephane Eranian <eranian@google.com>,
        Milian Wolff <milian.wolff@kdab.com>,
        Andi Kleen <andi@firstfloor.org>,
        Frederic Weisbecker <frederic@kernel.org>
Subject: Re: [PATCH 09/10] perf/cputime: Don't stop idle tick if there's live
 cputime event
Message-ID: <20180607154522.hyjmxn3q6zgcvsnx@two.firstfloor.org>
References: <20180606221513.11302-1-jolsa@kernel.org>
 <20180606221513.11302-10-jolsa@kernel.org>
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On Thu, Jun 07, 2018 at 12:15:12AM +0200, Jiri Olsa wrote:
> Disable stopping of the idle tick when having live cputime
> event. When the tick is disabled, the idle counts are out
> of date until next tick/update and perf cputime PMU provides
> misleading counts.

I really don't like this. This can totally change performance
(e.g. less Turbo due to less idle) and performance tools shouldn't
change the performance profile drastically.

-Andi