Date: Mon, 22 Oct 2012 06:53:58 -0700
From: Andi Kleen <ak@linux.intel.com>
To: Stephane Eranian <eranian@google.com>
Cc: linux-kernel@vger.kernel.org, peterz@infradead.org, mingo@elte.hu,
        acme@redhat.com, jolsa@redhat.com
Subject: Re: [PATCH v2 1/2] perf tools: add event modifier to request
 exclusive PMU access
Message-ID: <20121022135358.GJ2095@tassilo.jf.intel.com>
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On Mon, Oct 22, 2012 at 03:20:51PM +0200, Stephane Eranian wrote:
> This patch adds the x modifier for events. It allows users to
> request exclusive PMU access (attr->exclusive):
> 
> perf stat -e cycles:x ......
> or
> perf stat -e cpu/cycles/x ....
> 
> Exclusive mode is a feature of perf_events which was not yet
> supported by the perf tool. Some events may require exclusive
> PMU access (like on Intel SandyBridge).

You probably should add it also to be readable from sysfs

(like I did with precise in my haswell patchkit)

Then the SNB version of instructions-p can just force this 
without the user having to do anything special.

-Andi
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