linux-kernel - Re: [PATCH 17/18] sched: Retry migration of tasks to CPU on a preferred node

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: <20130801154604.GF2296@suse.de>
Date:	Thu, 1 Aug 2013 16:46:04 +0100
From:	Mel Gorman <mgorman@...e.de>
To:	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
Cc:	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Ingo Molnar <mingo@...nel.org>,
	Andrea Arcangeli <aarcange@...hat.com>,
	Johannes Weiner <hannes@...xchg.org>,
	Linux-MM <linux-mm@...ck.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 17/18] sched: Retry migration of tasks to CPU on a
 preferred node

On Thu, Aug 01, 2013 at 10:43:27AM +0530, Srikar Dronamraju wrote:
> * Mel Gorman <mgorman@...e.de> [2013-07-15 16:20:19]:
> 
> > When a preferred node is selected for a tasks there is an attempt to migrate
> > the task to a CPU there. This may fail in which case the task will only
> > migrate if the active load balancer takes action. This may never happen if
> 
> Apart from load imbalance or heavily loaded cpus on the preferred node,
> what could be the other reasons for migration failure with
> migrate_task_to()?

These were the reasons I expected that migration might fail.

> I see it almost similar to active load balance except
> for pushing instead of pulling tasks.
> 
> If load imbalance is the only reason, do we need to retry? If the task
> is really so attached to memory on that node, shouldn't we getting
> task_numa_placement hit before the next 5 seconds? 
> 

Depends on the PTE scanning rate.

-- 
Mel Gorman
SUSE Labs
--
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/