Re: sched: tweak select_idle_sibling to look for idle threads

From	Mike Galbraith <mgalbraith@suse.de>
Newsgroups	linux.kernel
Subject	Re: sched: tweak select_idle_sibling to look for idle threads
Date	2016-04-12 20:20 +0200
Message-ID	<rnb4R-3n3-3@gated-at.bofh.it> (permalink)
References	(3 earlier) <rmtGy-1Fh-15@gated-at.bofh.it> <rmC78-6h-1@gated-at.bofh.it> <rmUx3-6uV-1@gated-at.bofh.it> <rmYr0-1aa-9@gated-at.bofh.it> <rn6ye-83Y-21@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Tue, 2016-04-12 at 09:27 -0400, Chris Mason wrote:
> I
> can always add the tunable to flip things on/off but I'd prefer that we
> find a good set of defaults, mostly so the FB production runtime is the
> common config instead of the special snowflake.

Yeah, generic has a much better chance to actually get merged, just
need a very solid chain on the lurking beast from hell.  Hm...

The last time we went through this, the problem child was the waker of
many in your load.  With tiny twiddle to wake_wide(), all was allegedly
well, or at least that's the impression I was left with.  That leads me
to a pseudo-random thought: iff that waker of many is still at the
root, you could try using wake_wide() as the full search trigger, which
should shrink the attack surface available to the horror-from-hell
quite a lot.  Just a thought.

	-Mike

Thread

[PATCH RFC] select_idle_sibling experiments Chris Mason <clm@fb.com> - 2016-04-05 20:20 +0200
  Re: [PATCH RFC] select_idle_sibling experiments Bastien Bastien Philbert <bastienphilbert@gmail.com> - 2016-04-05 20:50 +0200
    Re: [PATCH RFC] select_idle_sibling experiments Chris Mason <clm@fb.com> - 2016-04-05 21:30 +0200
  Re: [PATCH RFC] select_idle_sibling experiments Matt Fleming <matt@codeblueprint.co.uk> - 2016-04-05 22:10 +0200
    Re: [PATCH RFC] select_idle_sibling experiments Bastien Philbert <bastienphilbert@gmail.com> - 2016-04-05 23:10 +0200
    Re: [PATCH RFC] select_idle_sibling experiments Chris Mason <clm@fb.com> - 2016-04-06 02:50 +0200
  Re: [PATCH RFC] select_idle_sibling experiments Mike Galbraith <mgalbraith@suse.de> - 2016-04-06 09:30 +0200
    Re: [PATCH RFC] select_idle_sibling experiments Chris Mason <clm@fb.com> - 2016-04-06 15:40 +0200
    Re: [PATCH RFC] select_idle_sibling experiments Chris Mason <clm@fb.com> - 2016-04-09 19:40 +0200
      Re: [PATCH RFC] select_idle_sibling experiments Matt Fleming <matt@codeblueprint.co.uk> - 2016-04-12 23:50 +0200
        Re: [PATCH RFC] select_idle_sibling experiments Mike Galbraith <mgalbraith@suse.de> - 2016-04-13 05:50 +0200
          Re: [PATCH RFC] select_idle_sibling experiments Chris Mason <clm@fb.com> - 2016-04-13 18:00 +0200
  Re: [PATCH RFC] select_idle_sibling experiments Chris Mason <clm@fb.com> - 2016-04-07 17:20 +0200
  sched: tweak select_idle_sibling to look for idle threads Chris Mason <clm@fb.com> - 2016-04-09 21:10 +0200
    Re: sched: tweak select_idle_sibling to look for idle threads Mike Galbraith <mgalbraith@suse.de> - 2016-04-10 12:10 +0200
      Re: sched: tweak select_idle_sibling to look for idle threads Chris Mason <clm@fb.com> - 2016-04-10 14:40 +0200
        Re: sched: tweak select_idle_sibling to look for idle threads Mike Galbraith <mgalbraith@suse.de> - 2016-04-10 14:50 +0200
      Re: sched: tweak select_idle_sibling to look for idle threads Chris Mason <clm@fb.com> - 2016-04-10 22:00 +0200
        Re: sched: tweak select_idle_sibling to look for idle threads Mike Galbraith <mgalbraith@suse.de> - 2016-04-11 07:00 +0200
          Re: sched: tweak select_idle_sibling to look for idle threads Chris Mason <clm@fb.com> - 2016-04-12 02:40 +0200
            Re: sched: tweak select_idle_sibling to look for idle threads Mike Galbraith <mgalbraith@suse.de> - 2016-04-12 06:50 +0200
              Re: sched: tweak select_idle_sibling to look for idle threads Chris Mason <clm@fb.com> - 2016-04-12 15:30 +0200
                Re: sched: tweak select_idle_sibling to look for idle threads Mike Galbraith <mgalbraith@suse.de> - 2016-04-12 20:20 +0200
                Re: sched: tweak select_idle_sibling to look for idle threads Chris Mason <clm@fb.com> - 2016-04-12 22:10 +0200
                Re: sched: tweak select_idle_sibling to look for idle threads Mike Galbraith <mgalbraith@suse.de> - 2016-04-13 05:20 +0200
                Re: sched: tweak select_idle_sibling to look for idle threads Chris Mason <clm@fb.com> - 2016-04-13 15:50 +0200
                Re: sched: tweak select_idle_sibling to look for idle threads Mike Galbraith <mgalbraith@suse.de> - 2016-04-13 16:30 +0200
                Re: sched: tweak select_idle_sibling to look for idle threads Chris Mason <clm@fb.com> - 2016-04-13 16:40 +0200
                Re: sched: tweak select_idle_sibling to look for idle threads Mike Galbraith <mgalbraith@suse.de> - 2016-04-13 17:10 +0200
                Re: sched: tweak select_idle_sibling to look for idle threads Mike Galbraith <mgalbraith@suse.de> - 2016-04-13 17:40 +0200

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