Re: [Xen-devel] [PATCH] Fix xenoprof counter overflow check

To:	"Keir Fraser" <keir.fraser@xxxxxxxxxxxxx>
Subject:	Re: [Xen-devel] [PATCH] Fix xenoprof counter overflow check
From:	"Niraj Tolia" <ntolia@xxxxxxxxx>
Date:	Tue, 6 Jan 2009 10:37:04 -0800
Cc:	xen-devel@xxxxxxxxxxxxxxxxxxx
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On Tue, Jan 6, 2009 at 6:10 AM, Keir Fraser <keir.fraser@xxxxxxxxxxxxx> wrote:

On 06/01/2009 04:49, "Niraj Tolia" <ntolia@xxxxxxxxx> wrote:

> # HG changeset patch
> # User Niraj Tolia <ntolia@xxxxxxxxx>
> # Date 1231217146 28800
> # Node ID eb1ad7bbdaf3ae553a6bf319180b5880f5ac4307
> # Parent 8417ddc981b407753f966c568ef8c7b673d8d22a
> Xenoprof patch to fix the counter overflow check for CPUs with counter
> width > 32
>
> I had to port this patch from mainline Linux where it can be found at
> http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;
> h=7c64ade53a6f977d73f16243865c42ceae999aea
>
> Signed-off-by: Niraj Tolia <ntolia@xxxxxxxxx>

This patch can't possibly build, and is pointless anyway since the overflow

While the mainline patch won't build, the one attached definitely does. That said, I see your point about the overflow. Now I need to figure out why this broken patch actually enables xenoprof to work on my Intel Xeon. The only reason would be the switch from CTR_READ() (which uses rdmsr() internally) to rdmsrl() but let me dig into it.

Cheers,
Niraj

width check is still hardcoded to 32 bits in CTR_OVERFLOWED().

-- Keir

--
Niraj Tolia, Researcher, HP Labs
http://www.hpl.hp.com/personal/Niraj_Tolia/

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Re: [Xen-devel] [PATCH] Fix xenoprof counter overflow check