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Date: Fri, 26 Aug 2011 22:46:56 +0800 From: Zhao Jin <cronozhj@...il.com> To: Christoph Lameter <cl@...ux.com> Cc: penberg@...nel.org, mpm@...enic.com, trivial@...nel.org, linux-kernel@...r.kernel.org Subject: Re: [PATCH] slab: avoid unnecessary touching of a partial slab On Fri, 2011-08-26 at 09:08 -0500, Christoph Lameter wrote: > On Fri, 26 Aug 2011, Zhao Jin wrote: > > > In cache_alloc_refill(), after refilling from a partial slab, if the > > slab remains partial, it would be deleted from and then added again to > > the partial list. As the slab is the first element in the list before > > deletion, such behavior has no effect. This patch avoids touching the > > slab in this case. > > The list_del/list_add action is a list_move. But in cache_alloc_refill(), it is the first slab (that is: its list field is pointed by the l3->slabs_partial.next) that is picked from the partial list for refilling. Assume it remains partial after that. Since list_add inserts a new element after the head (l3->slabs_partial), the position of the slab in the partial list won't change after list_del/list_add: it will be still the first element. Therefore, list_del/list_add has done nothing actually in this case. Regards, zhj -- 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/
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