linux-kernel - Re: [PATCH 2/3] perf/x86/pebs: add workaround for broken OVFL status on HSW

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Date:	Thu, 10 Mar 2016 08:10:03 -0800
From:	Stephane Eranian <eranian@...gle.com>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	Andi Kleen <ak@...ux.intel.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	"mingo@...e.hu" <mingo@...e.hu>,
	"Liang, Kan" <kan.liang@...el.com>, Jiri Olsa <jolsa@...hat.com>,
	Namhyung Kim <namhyung@...nel.org>,
	Adrian Hunter <adrian.hunter@...el.com>
Subject: Re: [PATCH 2/3] perf/x86/pebs: add workaround for broken OVFL status
 on HSW

On Thu, Mar 10, 2016 at 5:53 AM, Peter Zijlstra <peterz@...radead.org> wrote:
> On Mon, Mar 07, 2016 at 01:18:40PM +0100, Peter Zijlstra wrote:
>> On Mon, Mar 07, 2016 at 11:24:13AM +0100, Peter Zijlstra wrote:
>>
>> > I suspect Andi is having something along:
>> >
>> >  lkml.kernel.org/r/1445458568-16956-1-git-send-email-andi@...stfloor.org
>> >
>> > applied to his tree.
>>
>> OK, I munged a bunch of patches together, please have a hard look at the
>> end result found in:
>>
>>   git://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git perf/core
>
> So while running tip/master I just triggered the "irq loop stuck" warn
> on my IVB, with status==1, and PMC0 didn't look weird at all.
>
> I've not seen that for a fair while. But it does show it still happens
> on not quite antique hardware.

Yes, as I said, tip.git is missing something, with Andi's missing 3
patches I do not get
that. But with them, I was getting the problem I described earlier, so
I just posted a
patch to handle that particular case where bit 62 is not set, yet PEBS
counters show
overflow. Test it.

Thanks.