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Date: Fri, 29 Apr 2016 10:52:33 +0200
From: Peter Zijlstra <peterz@infradead.org>
To: David Carrillo-Cisneros <davidcc@google.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Ingo Molnar <mingo@redhat.com>,
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        Stephane Eranian <eranian@google.com>, Paul Turner <pjt@google.com>,
        x86@kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 25/32] sched: introduce the finish_arch_pre_lock_switch()
 scheduler hook
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On Thu, Apr 28, 2016 at 09:43:31PM -0700, David Carrillo-Cisneros wrote:
> This hook allows architecture specific code to be called at the end of
> the task switch and after perf_events' context switch but before the
> scheduler lock is released.
> 
> The specific use case in this series is to avoid multiple writes to a slow
> MSR until all functions which modify such register in task switch have
> finished.

Yeah, no. This really need way more justification. Why can't you use the
regular perf sched-in stuff for CQM?