linux-kernel - Re: [RT LATENCY] 249 microsecond latency caused by slub's unfreeze

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Date:	Wed, 5 Jun 2013 14:06:47 +0000
From:	Christoph Lameter <cl@...ux.com>
To:	JoonSoo Kim <js1304@...il.com>
cc:	Steven Rostedt <rostedt@...dmis.org>,
	Joonsoo Kim <iamjoonsoo.kim@....com>,
	LKML <linux-kernel@...r.kernel.org>,
	RT <linux-rt-users@...r.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Clark Williams <clark@...hat.com>,
	Pekka Enberg <penberg@...nel.org>
Subject: Re: [RT LATENCY] 249 microsecond latency caused by slub's
 unfreeze_partials() code.

On Wed, 5 Jun 2013, JoonSoo Kim wrote:

> I knew that we need the other nodes pages if we consistently allocate
> from there.
> In allocation path, it is reasonable.
> But, in free path, it is not reasonable that we put other nodes' page
> to cpu partial list.

It is reasonable. An "other nodes page" on the cpu partial list will
decrease the synchronization necessary to free other objects to that
page. And multiple objects from a remote node are typically freed in on go.

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