linux-kernel - Re: [PATCH 1/3] perf, x86: Blacklist all MEM_*

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Message-ID: <CABPqkBSTMJebZLjvLhdQ1hiemoqvO2t=vi+CG=yLjkFabOr8XQ@mail.gmail.com>
Date:	Wed, 15 May 2013 16:20:46 +0200
From:	Stephane Eranian <eranian@...gle.com>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	Andi Kleen <ak@...ux.intel.com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Ingo Molnar <mingo@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/3] perf, x86: Blacklist all MEM_*_RETIRED events for IVB

Hi,

Based on our testing, it appears the corruption occurs only
when the MEM_* events are used and only on the sibling
counter. In other words, if HT0 has MEM_* in cntr0, then
HT1 cntr0 cannot be used, otherwise whatever is there may
get corrupted. So I think we could enhance Andi's initial patch
to handle this case instead of blacklist those events. They are
very important events.


On Fri, May 3, 2013 at 7:00 PM, Peter Zijlstra <peterz@...radead.org> wrote:
> On Fri, May 03, 2013 at 07:35:07AM -0700, Andi Kleen wrote:
>> On Fri, May 03, 2013 at 02:11:23PM +0200, Peter Zijlstra wrote:
>> > Errata BV98 states that all MEM_*_RETIRED events corrupt the counter
>> > value of the SMT sibling's counters. Blacklist these events
>>
>> I disagree with this patch. This is just overkill and not needed
>> at all.
>
> Then give me a patch that both completely describes the problem and ensures
> isolation so that no counters get corrupted (and isn't too invasive).
>
> So far you've failed on both counts.
>
>
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