From: Rik van Riel <riel@redhat.com>
To: Richard Kennedy <richard@rsk.demon.co.uk>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>,
Andrew Morton <akpm@linux-foundation.org>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
lkml <linux-kernel@vger.kernel.org>,
Jens Axboe <jens.axboe@oracle.com>, Nick Piggin <npiggin@suse.de>,
"Theodore Ts'o" <tytso@mit.edu>
Subject: Re: [PATCH] fs: buffer_head, remove kmem_cache constructor to reduce memory usage under slub
Date: Tue, 09 Feb 2010 11:48:20 -0500 [thread overview]
Message-ID: <4B7191D4.4000101@redhat.com> (raw)
In-Reply-To: <1265722191.4033.36.camel@localhost>
On 02/09/2010 08:29 AM, Richard Kennedy wrote:
> fs: Remove the buffer_head kmem_cache constructor to reduce memory usage
> under slub.
>
> When using slub, having a kmem_cache constructor forces slub to add a
> free pointer to the size of the cached object, which can have a
> significant impact to the number of small objects that can fit into a
> slab.
>
> As buffer_head is relatively small and we can have large numbers of
> them, removing the constructor is a definite win.
>
> On x86_64 removing the constructor gives me 39 objects/slab, 3 more than
> without the patch. And on x86_32 73 objects/slab, which is 9 more.
>
> As alloc_buffer_head() already initializes each new object there is very
> little difference in actual code run.
>
> Signed-off-by: Richard Kennedy<richard@rsk.demon.co.uk>
Reviewed-by: Rik van Riel <riel@redhat.com>
--
All rights reversed.
prev parent reply other threads:[~2010-02-09 16:49 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-02-09 13:29 [PATCH] fs: buffer_head, remove kmem_cache constructor to reduce memory usage under slub Richard Kennedy
2010-02-09 14:31 ` Nick Piggin
2010-02-09 16:48 ` Rik van Riel [this message]
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