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SubjectRe: [lkp] [mm/vmstat] 6cdb18ad98: -8.5% will-it-scale.per_thread_ops
On Wed, Jan 06, 2016 at 11:20:55AM +0800, kernel test robot wrote:
> FYI, we noticed the below changes on
>
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> commit 6cdb18ad98a49f7e9b95d538a0614cde827404b8 ("mm/vmstat: fix overflow in mod_zone_page_state()")
>
>
> =========================================================================================
> compiler/cpufreq_governor/kconfig/rootfs/tbox_group/test/testcase:
> gcc-4.9/performance/x86_64-rhel/debian-x86_64-2015-02-07.cgz/ivb42/pread1/will-it-scale
>
> commit:
> cc28d6d80f6ab494b10f0e2ec949eacd610f66e3
> 6cdb18ad98a49f7e9b95d538a0614cde827404b8
>
> cc28d6d80f6ab494 6cdb18ad98a49f7e9b95d538a0
> ---------------- --------------------------
> %stddev %change %stddev
> \ | \
> 2733943 ± 0% -8.5% 2502129 ± 0% will-it-scale.per_thread_ops
> 3410 ± 0% -2.0% 3343 ± 0% will-it-scale.time.system_time
> 340.08 ± 0% +19.7% 406.99 ± 0% will-it-scale.time.user_time
> 69882822 ± 2% -24.3% 52926191 ± 5% cpuidle.C1-IVT.time
> 340.08 ± 0% +19.7% 406.99 ± 0% time.user_time
> 491.25 ± 6% -17.7% 404.25 ± 7% numa-vmstat.node0.nr_alloc_batch
> 2799 ± 20% -36.6% 1776 ± 0% numa-vmstat.node0.nr_mapped
> 630.00 ±140% +244.4% 2169 ± 1% numa-vmstat.node1.nr_inactive_anon

Hmm... this is odd. I did review all callers of mod_zone_page_state() and
couldn't find anything obvious that would go wrong after the int -> long
change.

I also tried the "pread1_threads" test case from
https://github.com/antonblanchard/will-it-scale.git

However the results seem to vary a lot after a reboot(!), at least on s390.

So I'm not sure if this is really a regression.



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