linux-kernel - Re: [RFC PATCH v3 0/3] sched: simplify the select_task_rq

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]

Message-ID: <1361525962.26780.47.camel@laptop>
Date:	Fri, 22 Feb 2013 10:39:22 +0100
From:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
To:	Michael Wang <wangyun@...ux.vnet.ibm.com>
Cc:	Mike Galbraith <efault@....de>, Ingo Molnar <mingo@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Paul Turner <pjt@...gle.com>,
	Andrew Morton <akpm@...ux-foundation.org>, alex.shi@...el.com,
	Ram Pai <linuxram@...ibm.com>,
	"Nikunj A. Dadhania" <nikunj@...ux.vnet.ibm.com>,
	Namhyung Kim <namhyung@...nel.org>
Subject: Re: [RFC PATCH v3 0/3] sched: simplify the select_task_rq_fair()

On Fri, 2013-02-22 at 17:10 +0800, Michael Wang wrote:
> On 02/22/2013 04:21 PM, Peter Zijlstra wrote:
> > On Fri, 2013-02-22 at 10:36 +0800, Michael Wang wrote:
> >> According to my understanding, in the old world, wake_affine() will
> >> only
> >> be used if curr_cpu and prev_cpu share cache, which means they are in
> >> one package, whatever search in llc sd of curr_cpu or prev_cpu, we
> >> won't
> >> have the chance to spread the task out of that package.
> > 
> > Nah, look at where SD_WAKE_AFFINE is set. Only 'remote/big' NUMA domains
> > don't have it set, but 'small' NUMA systems will have it set over the
> > entire domain tree.
> 
> Oh, I missed that point...
> 
> But I don't get the reason to make NUMA level affine, cpus in different
> nodes share cache? doesn't make sense...

Contrary, it makes more sense, the more expensive it is to run 'remote'
the better it is to pull 'related' tasks together.



--
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/