linux-kernel - Re: [PATCH v1 0/2] perf: Drop leaked kernel samples

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Message-ID: <a8ba2079-b880-a145-a4e0-754d58ccdc8f@linux.intel.com>
Date:   Fri, 15 Jun 2018 16:24:49 +0800
From:   "Jin, Yao" <yao.jin@...ux.intel.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     acme@...nel.org, jolsa@...nel.org, mingo@...hat.com,
        alexander.shishkin@...ux.intel.com, me@...ehuey.com,
        Linux-kernel@...r.kernel.org, vincent.weaver@...ne.edu,
        will.deacon@....com, eranian@...gle.com, namhyung@...nel.org,
        ak@...ux.intel.com, kan.liang@...el.com, yao.jin@...el.com
Subject: Re: [PATCH v1 0/2] perf: Drop leaked kernel samples



On 6/15/2018 4:12 PM, Peter Zijlstra wrote:
> On Fri, Jun 15, 2018 at 04:01:45PM +0800, Jin, Yao wrote:
> 
>> Bring more overhead to kernel if we zero the bits considering the number of
>> leaked samples may be not too small?
> 
> Keeping the samples at least allows you to know how many samples
> happened and such things.
> 

Yeah, agree, but a little bit overhead ...

>> And the skid information may be interesting (see example of hitting on
>> page_fault in previous mail). If we zero it, we will not know.
> 
> If you throw them out the window you also don't know, do you?
> 

Yes, default I can't know that window. I have to use sysctl to enable.

Thanks
Jin Yao