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From: Peter Zijlstra <peterz@infradead.org>
To: Stephane Eranian <eranian@google.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
	"mingo@elte.hu" <mingo@elte.hu>,
	"ak@linux.intel.com" <ak@linux.intel.com>,
	Arnaldo Carvalho de Melo <acme@redhat.com>,
	Jiri Olsa <jolsa@redhat.com>
Subject: Re: [PATCH 2/2] perf: SNB exclusive PMU access for INST_RETIRED:PREC_DIST
Date: Fri, 19 Oct 2012 18:45:52 +0200	[thread overview]
Message-ID: <1350665152.2768.41.camel@twins> (raw)
In-Reply-To: <CABPqkBQ5kCyGByFS-D62RYg2VUf_W-rJKDH=AzyrcaBPVY-eFQ@mail.gmail.com>

On Fri, 2012-10-19 at 18:31 +0200, Stephane Eranian wrote:
> On Fri, Oct 19, 2012 at 6:27 PM, Peter Zijlstra <peterz@infradead.org> wrote:
> > On Fri, 2012-10-19 at 16:52 +0200, Stephane Eranian wrote:
> >> +static int intel_pebs_aliases_snb(struct perf_event *event)
> >> +{
> >> +       u64 cfg = event->hw.config;
> >> +       /*
> >> +        * for INST_RETIRED.PREC_DIST to work correctly with PEBS, it must
> >> +        * be measured alone on SNB (exclusive PMU access) as per Intel SDM.
> >> +        */
> >> +       if ((cfg & INTEL_ARCH_EVENT_MASK) == 0x01c0 && !event->attr.exclusive) {
> >> +               pr_info("perf: INST_RETIRED.PREC_DIST only works in exclusive mode\n");
> >> +               return -EINVAL;
> >
> > This isn't limited to admin, right? So the above turns into a DoS on the
> > console.
> >
> Ok, so how about a WARN_ON_ONCE() instead?

That should be fine I guess ;-)

  reply	other threads:[~2012-10-19 16:46 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-10-19 14:52 [PATCH 0/2] perf: enforce exclusive PMU access for SNB INST_RETIRED:PREC_DIST Stephane Eranian
2012-10-19 14:52 ` [PATCH 1/2] perf tools: add event modifier to request exclusive PMU access Stephane Eranian
2012-10-19 15:13   ` Peter Zijlstra
2012-10-19 15:17     ` Stephane Eranian
2012-10-19 15:23       ` Jiri Olsa
2012-10-19 15:47         ` Stephane Eranian
2012-10-19 15:53           ` Jiri Olsa
2012-10-19 15:58             ` Stephane Eranian
2012-10-19 15:46       ` Andi Kleen
2012-10-19 16:07         ` Jiri Olsa
2012-10-19 14:52 ` [PATCH 2/2] perf: SNB exclusive PMU access for INST_RETIRED:PREC_DIST Stephane Eranian
2012-10-19 15:49   ` Andi Kleen
2012-10-19 15:58     ` Stephane Eranian
2012-10-19 16:27   ` Peter Zijlstra
2012-10-19 16:31     ` Stephane Eranian
2012-10-19 16:45       ` Peter Zijlstra [this message]
2012-10-19 17:20         ` Andi Kleen
2012-10-21 16:55           ` Ingo Molnar
2012-10-21 17:54             ` Stephane Eranian
2012-10-21 18:03               ` Ingo Molnar
2012-10-22 11:31                 ` Stephane Eranian
2012-10-24  8:15                   ` Ingo Molnar

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