linux-kernel - Re: [PATCH 4/9] slab: defer slab_destroy in free

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Message-ID: <alpine.DEB.2.10.1402141239010.12887@nuc>
Date:	Fri, 14 Feb 2014 12:39:58 -0600 (CST)
From:	Christoph Lameter <cl@...ux.com>
To:	Joonsoo Kim <iamjoonsoo.kim@....com>
cc:	Pekka Enberg <penberg@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	David Rientjes <rientjes@...gle.com>,
	Wanpeng Li <liwanp@...ux.vnet.ibm.com>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, Joonsoo Kim <js1304@...il.com>
Subject: Re: [PATCH 4/9] slab: defer slab_destroy in free_block()

On Fri, 14 Feb 2014, Joonsoo Kim wrote:

> In free_block(), if freeing object makes new free slab and number of
> free_objects exceeds free_limit, we start to destroy this new free slab
> with holding the kmem_cache node lock. Holding the lock is useless and,
> generally, holding a lock as least as possible is good thing. I never
> measure performance effect of this, but we'd be better not to hold the lock
> as much as possible.

This is also good because kmem_cache_free is no longer called while
holding the node lock. So we avoid one case of recursion.

Acked-by: Christoph Lameter <cl@...ux.com>
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