Re: [RFC][PATCH 0/7] sched: select_idle_siblings rewrite

From: Chris Mason
Date: Wed May 11 2016 - 10:20:22 EST


On Mon, May 09, 2016 at 12:48:07PM +0200, Peter Zijlstra wrote:
> Hai,
>
> here be a semi coherent patch series for the recent select_idle_siblings()
> tinkering. Happy benchmarking..

I ran a few more rounds of the production benchmarks, and NO_AVG_CPU is
consistently faster by about 5% than AVG_CPU. I think what's happening
here is the production runs are ramping up load in a finer grained setup
than schbench, and production is able to see the AVG_CPU calculations
back off the scan too soon (for us anyway).

I'm going to play around with schbench to try and model this better, but
so far this is a clear win over unpatched v4.6.

-chris