linux-kernel - Re: [patch v3] sched: fix select_idle

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Mon, 11 Jun 2012 19:22:11 +0200
From:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
To:	Mike Galbraith <efault@....de>
Cc:	lkml <linux-kernel@...r.kernel.org>,
	Suresh Siddha <suresh.b.siddha@...el.com>,
	Paul Turner <pjt@...gle.com>,
	Arjan Van De Ven <arjan@...ux.intel.com>
Subject: Re: [patch v3] sched: fix select_idle_sibling() induced bouncing

On Mon, 2012-06-11 at 18:57 +0200, Mike Galbraith wrote:

> Traversing an entire package is not only expensive, it also leads to tasks
> bouncing all over a partially idle and possible quite large package.  Fix
> that up by assigning a 'buddy' CPU to try to motivate.  Each buddy may try
> to motivate that one other CPU, if it's busy, tough, it may then try it's
> SMT sibling, but that's all this optimization is allowed to cost.
> 
> Sibling cache buddies are cross-wired to prevent bouncing.
> 
> Signed-off-by: Mike Galbraith <efault@....de>

The patch could do with a little comment on how you achieve the
cross-wiring because staring at the code I go cross-eyed again ;-)

Anyway, I think I'll grab it since nobody seems to have any objections
and the numbers seem good.

PJT any progress on your load-tracking stuff? Arjan is interested in the
avg runtime estimation it has to make the whole wake an idle thing
conditional on.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/