linux-kernel - Re: [PATCH 0/7] slub: Fastpath optimization (especially for RT) V1

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Message-ID: <alpine.DEB.2.11.1412170935480.2047@gentwo.org>
Date:	Wed, 17 Dec 2014 09:36:13 -0600 (CST)
From:	Christoph Lameter <cl@...ux.com>
To:	Joonsoo Kim <js1304@...il.com>
cc:	Joonsoo Kim <iamjoonsoo.kim@....com>, akpm@...uxfoundation.org,
	Steven Rostedt <rostedt@...dmis.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Linux Memory Management List <linux-mm@...ck.org>,
	Pekka Enberg <penberg@...nel.org>,
	Jesper Dangaard Brouer <brouer@...hat.com>
Subject: Re: [PATCH 0/7] slub: Fastpath optimization (especially for RT) V1

On Wed, 17 Dec 2014, Joonsoo Kim wrote:

> Ping... and I found another way to remove preempt_disable/enable
> without complex changes.
>
> What we want to ensure is getting tid and kmem_cache_cpu
> on the same cpu. We can achieve that goal with below condition loop.
>
> I ran Jesper's benchmark and saw 3~5% win in a fast-path loop over
> kmem_cache_alloc+free in CONFIG_PREEMPT.
>
> 14.5 ns -> 13.8 ns
>
> See following patch.

Good idea. How does this affect the !CONFIG_PREEMPT case?
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