linux-kernel - Re: [patch 4/6] x86, perf, cqm: Avoid pointless msr write

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Message-ID: <20150519091755.GC17401@codeblueprint.co.uk>
Date:	Tue, 19 May 2015 10:17:55 +0100
From:	Matt Fleming <matt@...eblueprint.co.uk>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Vikas Shivappa <vikas.shivappa@...ux.intel.com>,
	x86@...nel.org, Matt Fleming <matt.fleming@...el.com>,
	Will Auld <will.auld@...el.com>,
	Kanaka Juvva <kanaka.d.juvva@...el.com>
Subject: Re: [patch 4/6] x86, perf, cqm: Avoid pointless msr write

On Tue, 19 May, at 12:00:55AM, Thomas Gleixner wrote:
> If the usage counter is non-zero there is no point to update the rmid
> in the PQR MSR.
> 
> Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
> ---
>  arch/x86/kernel/cpu/perf_event_intel_cqm.c |    8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)

Good catch.

Acked-by: Matt Fleming <matt.fleming@...el.com>

-- 
Matt Fleming, Intel Open Source Technology Center
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