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 14:30 +0200
Message-ID	<tIPcB-25W-11@gated-at.bofh.it> (permalink)
References	<tIFPY-3RD-9@gated-at.bofh.it> <tIMoq-8v4-11@gated-at.bofh.it> <tIOTf-1TM-9@gated-at.bofh.it> <tIP2V-22w-7@gated-at.bofh.it>
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On 5/19/2017 8:10 PM, Peter Zijlstra wrote:
> On Fri, May 19, 2017 at 08:06:09PM +0800, Jin, Yao wrote:
>> SNIP
>>
>>> I would much rather see this in generic code, somewhere around
>>> __perf_event_overflow() I suppose. That would retain proper accounting
>>> for the interrupt rate etc..
>>>
>>> Also it would work for all architectures. Because I'm thinking more than
>>> just x86 will suffer from skid.
>> Yes, moving to generic code is better.  Thanks for the suggestion! I will do
>> that.
>>
>>> If you're really worried, I suppose you can put it behind a PERF_PMU_CAP
>>> flag or something.
>> I guess what you are suggesting is to add checking like:
>>
>> if (is_sampling_event(event)) {
>>      if (event->pmu->capabilities & PERF_PMU_CAP_NO_INTERRUPT) {
>>          return;
>>      }
>> }
> 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.

If the event's capabilities is set with PERF_PMU_CAP_NO_SKID, it should 
skip the checking and keep current behavior.

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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