Re: [PATCH] sched: Reduce contention in update_cfs_rq_blocked_load

From: Jason Low
Date: Wed Aug 06 2014 - 14:21:43 EST


On Tue, 2014-08-05 at 03:15 +0800, Yuyang Du wrote:
> Hi Jason,
>
> I am not sure whether you noticed my latest work: rewriting per entity load average
>
> http://article.gmane.org/gmane.linux.kernel/1760754
> http://article.gmane.org/gmane.linux.kernel/1760755
> http://article.gmane.org/gmane.linux.kernel/1760757
> http://article.gmane.org/gmane.linux.kernel/1760756
>
> which simply does not track blocked load average at all. Are you interested in
> testing the patchset with the workload you have?

Hi Yuyang,

I ran these tests with most of the AIM7 workloads to compare its
performance between a 3.16 kernel and the kernel with these patches
applied.

The table below contains the percent difference between the baseline
kernel and the kernel with the patches at various user counts. A
positive percent means the kernel with the patches performed better,
while a negative percent means the baseline performed better.

Based on these numbers, for many of the workloads, the change was
beneficial in those highly contended, while it had - impact in many
of the lightly/moderately contended case (10 to 90 users).

-----------------------------------------------------
| 10-90 | 100-1000 | 1100-2000
| users | users | users
-----------------------------------------------------
alltests | -3.37% | -10.64% | -2.25%
-----------------------------------------------------
all_utime | +0.33% | +3.73% | +3.33%
-----------------------------------------------------
compute | -5.97% | +2.34% | +3.22%
-----------------------------------------------------
custom | -31.61% | -10.29% | +15.23%
-----------------------------------------------------
disk | +24.64% | +28.96% | +21.28%
-----------------------------------------------------
fserver | -1.35% | +4.82% | +9.35%
-----------------------------------------------------
high_systime | -6.73% | -6.28% | +12.36%
-----------------------------------------------------
shared | -28.31% | -19.99% | -7.10%
-----------------------------------------------------
short | -44.63% | -37.48% | -33.62%
-----------------------------------------------------


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