linux-kernel - Re: [PATCH] perf/x86: fix uncore PCI fixed counter handling

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Message-ID: <20130910202245.GF11427@tassilo.jf.intel.com>
Date:	Tue, 10 Sep 2013 13:22:45 -0700
From:	Andi Kleen <ak@...ux.intel.com>
To:	Stephane Eranian <eranian@...gle.com>
Cc:	linux-kernel@...r.kernel.org, peterz@...radead.org, mingo@...e.hu,
	zheng.z.yan@...el.com
Subject: Re: [PATCH] perf/x86: fix uncore PCI fixed counter handling

On Mon, Sep 09, 2013 at 12:53:50PM -0700, Stephane Eranian wrote:
> 
> There was a bug in the handling of SNB-EP/IVB-EP uncore PCI
> fixed counters, e.g., IMC. It would cause erratic values to
> be returned for the IMC clockticks event. This was due to
> a bogus hwc->config value which was then written to PCI
> config space. The fixed counter has most fields marked as
> reserved with hw reset values of 0. Yet the kernel was
> defaulting to a hwc->config = ~0 and that was causing
> the issues. The patch sets the hwc->config values for fixed
> uncore event to 0. Now, the values of imc clockticks is
> correct.
>     
> $ perf stat -a -C 0 -e uncore_imc_0/clockticks/ -I 1000 sleep 10

Looks good to me.

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

-Andi
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