linux-kernel - Re: [PATCH 1/5] x86, perf: Fix LBR call stack save/restore

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Message-ID: <20151021143530.GM3533@two.firstfloor.org>
Date:	Wed, 21 Oct 2015 16:35:31 +0200
From:	Andi Kleen <andi@...stfloor.org>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	Andi Kleen <andi@...stfloor.org>, acme@...nel.org,
	jolsa@...nel.org, linux-kernel@...r.kernel.org,
	Andi Kleen <ak@...ux.intel.com>, stable@...r.kernel.org,
	Ingo Molnar <mingo@...nel.org>
Subject: Re: [PATCH 1/5] x86, perf: Fix LBR call stack save/restore

> Any idea who much more expensive that wrmsr() is compared to the rdmsr()
> it replaces?

I don't know.
> 
> If its significant we could think about having this behaviour depend on
> callstacks.

This function is only used for callstacks, otherwise it uses the LBR reset
path.

-Andi


-- 
ak@...ux.intel.com -- Speaking for myself only.
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