Re: [PATCH] perf/x86/intel: Drop kernel samples even though :u is specified

From	"Jin, Yao" <yao.jin@linux.intel.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH] perf/x86/intel: Drop kernel samples even though :u is specified
Date	2017-05-19 15:40 +0200
Message-ID	<tIQil-2MD-1@gated-at.bofh.it> (permalink)
References	(1 earlier) <tIMoq-8v4-11@gated-at.bofh.it> <tIOTf-1TM-9@gated-at.bofh.it> <tIP2V-22w-7@gated-at.bofh.it> <tIPcB-25W-11@gated-at.bofh.it> <tIPmi-2aO-11@gated-at.bofh.it>
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On 5/19/2017 8:36 PM, Peter Zijlstra wrote:
> On Fri, May 19, 2017 at 08:24:19PM +0800, Jin, Yao wrote:
>>> Ah, I was more thinking of something like PERF_PMU_CAP_NO_SKID or
>>> something that would skip the test and preserve current behaviour.
>> OK, I understand now. For example, for PEBS event, its capabilities should
>> be set with PERF_PMU_CAP_NO_SKID.
> Except you cannot in fact do that, since PEBS is the same struct pmu as
> the normal counters (they share counter space after all).
>
> Also, weren't there PEBS errata that would allow this to happen?
>
> But no, more for other architectures to opt out for some reason. But I'm
> thinking we want to start out by unconditionally doing this. It would be
> good to try and Cc most arch pmu maintainers on this though, so they can
> object.
>
I'm thinking v2 of patch will only do simple tasks:

1. Define PERF_PMU_CAP_NO_SKID but don't bind it to any event.

2. Move the skid checking from x86 specific code to generic code. Before 
performing skid checking, test the PERF_PMU_CAP_NO_SKID bit first.

For binding PERF_PMU_CAP_NO_SKID to event, that may be other arch 
related patches.

Thanks
Jin Yao

Thread

[PATCH] perf/x86/intel: Drop kernel samples even though :u is specified Jin Yao <yao.jin@linux.intel.com> - 2017-05-19 04:30 +0200
  Re: [PATCH] perf/x86/intel: Drop kernel samples even though :u is  specified Peter Zijlstra <peterz@infradead.org> - 2017-05-19 11:30 +0200
    Re: [PATCH] perf/x86/intel: Drop kernel samples even though :u is  specified Will Deacon <will.deacon@arm.com> - 2017-05-19 11:50 +0200
    Re: [PATCH] perf/x86/intel: Drop kernel samples even though :u is  specified "Jin, Yao" <yao.jin@linux.intel.com> - 2017-05-19 14:10 +0200
      Re: [PATCH] perf/x86/intel: Drop kernel samples even though :u is  specified Peter Zijlstra <peterz@infradead.org> - 2017-05-19 14:20 +0200
        Re: [PATCH] perf/x86/intel: Drop kernel samples even though :u is  specified "Jin, Yao" <yao.jin@linux.intel.com> - 2017-05-19 14:30 +0200
          Re: [PATCH] perf/x86/intel: Drop kernel samples even though :u is  specified Peter Zijlstra <peterz@infradead.org> - 2017-05-19 14:40 +0200
            Re: [PATCH] perf/x86/intel: Drop kernel samples even though :u is  specified "Jin, Yao" <yao.jin@linux.intel.com> - 2017-05-19 15:40 +0200
              Re: [PATCH] perf/x86/intel: Drop kernel samples even though :u is  specified "Jin, Yao" <yao.jin@linux.intel.com> - 2017-05-22 04:20 +0200
                Re: [PATCH] perf/x86/intel: Drop kernel samples even though :u is  specified Mark Rutland <mark.rutland@arm.com> - 2017-05-22 10:50 +0200
                Re: [PATCH] perf/x86/intel: Drop kernel samples even though :u is  specified Peter Zijlstra <peterz@infradead.org> - 2017-05-22 11:30 +0200
                Re: [PATCH] perf/x86/intel: Drop kernel samples even though :u is  specified "Jin, Yao" <yao.jin@linux.intel.com> - 2017-05-22 14:40 +0200

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