linux-kernel - Re: [lkp-robot] [mm] 7674270022: will-it-scale.per_process

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Date:   Tue, 8 Aug 2017 11:28:30 +0900
From:   Minchan Kim <minchan@...nel.org>
To:     kernel test robot <xiaolong.ye@...el.com>
Cc:     Nadav Amit <namit@...are.com>, linux-mm@...ck.org,
        nadav.amit@...il.com, linux-kernel@...r.kernel.org,
        akpm@...ux-foundation.org, Ingo Molnar <mingo@...hat.com>,
        Russell King <linux@...linux.org.uk>,
        Tony Luck <tony.luck@...el.com>,
        Martin Schwidefsky <schwidefsky@...ibm.com>,
        "David S. Miller" <davem@...emloft.net>,
        Heiko Carstens <heiko.carstens@...ibm.com>,
        Yoshinori Sato <ysato@...rs.sourceforge.jp>,
        Jeff Dike <jdike@...toit.com>, linux-arch@...r.kernel.org,
        lkp@...org
Subject: Re: [lkp-robot] [mm]  7674270022:  will-it-scale.per_process_ops
 -19.3% regression

Hi,

On Tue, Aug 08, 2017 at 09:19:23AM +0800, kernel test robot wrote:
> 
> Greeting,
> 
> FYI, we noticed a -19.3% regression of will-it-scale.per_process_ops due to commit:
> 
> 
> commit: 76742700225cad9df49f05399381ac3f1ec3dc60 ("mm: fix MADV_[FREE|DONTNEED] TLB flush miss problem")
> url: https://github.com/0day-ci/linux/commits/Nadav-Amit/mm-migrate-prevent-racy-access-to-tlb_flush_pending/20170802-205715
> 
> 
> in testcase: will-it-scale
> on test machine: 88 threads Intel(R) Xeon(R) CPU E5-2699 v4 @ 2.20GHz with 64G memory
> with following parameters:
> 
> 	nr_task: 16
> 	mode: process
> 	test: brk1
> 	cpufreq_governor: performance
> 
> test-description: Will It Scale takes a testcase and runs it from 1 through to n parallel copies to see if the testcase will scale. It builds both a process and threads based test in order to see any differences between the two.
> test-url: https://github.com/antonblanchard/will-it-scale

Thanks for the report.
Could you explain what kinds of workload you are testing?

Does it calls frequently madvise(MADV_DONTNEED) in parallel on multiple
threads?