linux-kernel - Re: CFS scheduler unfairly prefers pinned tasks

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Message-Id: <201510110943.t9B9hOGs028472@como.maths.usyd.edu.au>
Date:	Sun, 11 Oct 2015 20:43:24 +1100
From:	paul.szabo@...ney.edu.au
To:	umgwanakikbuti@...il.com
Cc:	linux-kernel@...r.kernel.org, peterz@...radead.org,
	wanpeng.li@...mail.com
Subject: Re: CFS scheduler unfairly prefers pinned tasks

I wrote:

  The Linux CFS scheduler prefers pinned tasks and unfairly
  gives more CPU time to tasks that have set CPU affinity.

I believe I have now solved the problem, simply by setting:

  for n in /proc/sys/kernel/sched_domain/cpu*/domain0/min_interval; do echo 0 > $n; done
  for n in /proc/sys/kernel/sched_domain/cpu*/domain0/max_interval; do echo 1 > $n; done

I am not sure what the domain1 values would be for (that I see exist
on my 4*E5-4627v2 server). So far I do not see any negative effects of
using these (extreme?) settings. (Explanation of what these things are
meant for, or pointers to documentation, would be appreciated.)

---

Thanks for the insightful discussion.

(Scary, isn't it?)

Thanks, Paul

Paul Szabo   psz@...hs.usyd.edu.au   http://www.maths.usyd.edu.au/u/psz/
School of Mathematics and Statistics   University of Sydney    Australia
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