Re: [PATCH] sched: Reduce contention in update_cfs_rq_blocked_load

[Jason Low <jason.low2@hp.com>]

On Fri, 2014-08-08 at 02:02 +0800, Yuyang Du wrote:
> On Wed, Aug 06, 2014 at 11:21:35AM -0700, Jason Low wrote:
> > 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%
> > -----------------------------------------------------
> > 
> Thanks, Jason. Sorry for late response.
> 
> What about the variation of the tests? The machine you test on?

Hi Yuyang,

These tests were also done on an 8 socket machine (80 cores). In terms
of variation between the average throughputs, typically the noise range
is about 2% in many of the workloads.

Jason