linux-kernel - Re: [PATCH 2/2][RESEND] slab: avoid unnecessary touching of a partial slab

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Message-ID: <alpine.LFD.2.02.1201231521340.11844@tux.localdomain>
Date:	Mon, 23 Jan 2012 15:22:33 +0200 (EET)
From:	Pekka Enberg <penberg@...nel.org>
To:	Zhao Jin <cronozhj@...il.com>
cc:	cl@...ux-foundation.org, mpm@...enic.com, rientjes@...gle.com,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2][RESEND] slab: avoid unnecessary touching of a partial
 slab

[ Replying to an old patch that I seem to have missed. ]

On Sat, 27 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.
>
> Signed-off-by: Zhao Jin <cronozhj@...il.com>

Looks good to me, Christoph, David?

> ---
> mm/slab.c |    7 +++----
> 1 files changed, 3 insertions(+), 4 deletions(-)
>
> diff --git a/mm/slab.c b/mm/slab.c
> index 82e0a0e..2d7a0f4 100644
> --- a/mm/slab.c
> +++ b/mm/slab.c
> @@ -3121,11 +3121,10 @@ retry:
> 		check_slabp(cachep, slabp);
>
> 		/* move slabp to correct slabp list: */
> -		list_del(&slabp->list);
> 		if (slabp->free == BUFCTL_END)
> -			list_add(&slabp->list, &l3->slabs_full);
> -		else
> -			list_add(&slabp->list, &l3->slabs_partial);
> +			list_move(entry, &l3->slabs_full);
> +		else if (entry != l3->slabs_partial.next)
> +			list_move(entry, &l3->slabs_partial);
> 	}
>
> must_grow:
> -- 
> 1.7.4.1
>
>