linux-kernel - Re: [PATCH 2/2] oprofile: Remove 'WQ on CPUx, prefer CPUy' warning

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Message-ID: <20120827160854.GC16230@one.firstfloor.org>
Date:	Mon, 27 Aug 2012 18:08:54 +0200
From:	Andi Kleen <andi@...stfloor.org>
To:	Robert Richter <robert.richter@....com>
Cc:	Ingo Molnar <mingo@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	oprofile-list <oprofile-list@...ts.sourceforge.net>,
	Andi Kleen <andi@...stfloor.org>
Subject: Re: [PATCH 2/2] oprofile: Remove 'WQ on CPUx, prefer CPUy' warning

On Fri, Aug 24, 2012 at 08:53:31PM +0200, Robert Richter wrote:
> Under certain workloads we see the following warnings:
> 
>  WQ on CPU0, prefer CPU1
>  WQ on CPU0, prefer CPU2
>  WQ on CPU0, prefer CPU3
> 
> It warns the user that the wq to access a per-cpu buffers runs not on
> the same cpu. This happens if the wq is rescheduled on a different cpu
> than where the buffer is located. This was probably implemented to
> detect performance issues. Not sure if there actually is one as the
> buffers are copied to a single buffer anyway which should be the
> actual bottleneck.
> 
> We wont change WQ implementation. Since a user can do nothing the
> warning is pointless. Removing it.

Looks good to me.

Acked-by: Andi Kleen <ak@...ux.intel.com>

-Andi
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