linux-kernel - Re: [perf/x86/amd] 471af006a7: will-it-scale.per_process

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Date:   Fri, 14 Feb 2020 20:02:01 +0800
From:   "Chen, Rong A" <rong.a.chen@...el.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Kim Phillips <kim.phillips@....com>,
        LKML <linux-kernel@...r.kernel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        lkp@...ts.01.org
Subject: Re: [perf/x86/amd] 471af006a7: will-it-scale.per_process_ops -7.6%
 regression



On 2/12/2020 8:18 PM, Peter Zijlstra wrote:
> On Wed, Feb 12, 2020 at 07:35:14PM +0800, kernel test robot wrote:
>> Greeting,
>>
>> FYI, we noticed a -7.6% regression of will-it-scale.per_process_ops due to commit:
>>
>>
>> commit: 471af006a747f1c535c8a8c6c0973c320fe01b22 ("perf/x86/amd: Constrain Large Increment per Cycle events")
>> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master
>>
>> in testcase: will-it-scale
>> on test machine: 88 threads Intel(R) Xeon(R) CPU E5-2699 v4 @ 2.20GHz with 128G memory
> That commit only changes code relevant to AMD machines; give you have
> this result on an Intel machine makes me think the bisect is flawed.

Hi,

Sorry for the inconvenience, the regression is stable on our platform, 
we're investigating it.

Best Regards,
Rong Chen