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Subject: Re: [PATCH] perf/x86/intel: Drop kernel samples even though :u is
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To: Peter Zijlstra <peterz@infradead.org>
Cc: acme@kernel.org, jolsa@kernel.org, mingo@redhat.com,
        alexander.shishkin@linux.intel.com, Linux-kernel@vger.kernel.org,
        ak@linux.intel.com, kan.liang@intel.com, yao.jin@intel.com,
        Will Deacon <will.deacon@arm.com>, Mark Rutland <mark.rutland@arm.com>
References: <1495189152-5766-1-git-send-email-yao.jin@linux.intel.com>
 <20170519092905.yivnfjyhblm5wiap@hirez.programming.kicks-ass.net>
From: "Jin, Yao" <yao.jin@linux.intel.com>
Message-ID: <eba28230-5a96-fbfe-0fb3-191921839a72@linux.intel.com>
Date: Fri, 19 May 2017 20:06:09 +0800
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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;
     }
}

Is my understanding correct?

Thanks
Jin Yao