From: Andrew Morton <akpm@linux-foundation.org>
To: Jan Kara <jack@suse.cz>
Cc: linux-kernel@vger.kernel.org, linux-ext4@vger.kernel.org,
linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH 01/11] quota: Improve locking
Date: Fri, 23 Jan 2009 23:49:12 -0800 [thread overview]
Message-ID: <20090123234912.f78d75a0.akpm@linux-foundation.org> (raw)
In-Reply-To: <1232129299-22018-2-git-send-email-jack@suse.cz>
On Fri, 16 Jan 2009 19:08:09 +0100 Jan Kara <jack@suse.cz> wrote:
> static DEFINE_SPINLOCK(dq_list_lock);
> +static DEFINE_SPINLOCK(dq_state_lock);
> DEFINE_SPINLOCK(dq_data_lock);
The chances are very good that two or even three of these locks will
all get placed into the same cacheline in main memory. The effects
will be quite bad if different CPUs (or, worse, different nodes) are
taking these locks.
For single, kernel-wide locks like these I think we should almost
always pad out to a cacheline.
With __cacheline_aligned_in_smp, rather than __cacheline_aligned.
Because spinlocks do take space even in uniprocessor builds.
There are probably lots of existing locks which should be converted.
next prev parent reply other threads:[~2009-01-24 7:49 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <yes>
2009-01-16 18:08 ` Quota fixes and improvements Jan Kara
2009-01-16 18:08 ` [PATCH 01/11] quota: Improve locking Jan Kara
2009-01-16 18:08 ` [PATCH 02/11] ocfs2: Remove ocfs2_dquot_initialize() and ocfs2_dquot_drop() Jan Kara
2009-01-16 18:08 ` [PATCH 03/11] ocfs2: Push out dropping of dentry lock to ocfs2_wq Jan Kara
2009-01-16 18:08 ` [PATCH 04/11] ocfs2: Fix possible deadlock in ocfs2_write_dquot() Jan Kara
2009-01-16 18:08 ` [PATCH 05/11] quota: Add quota reservation support Jan Kara
2009-01-16 18:08 ` [PATCH 06/11] quota: Add quota reservation claim and released operations Jan Kara
2009-01-16 18:08 ` [PATCH 07/11] quota: Use inode->i_blkbits to get block bits Jan Kara
2009-01-16 18:08 ` [PATCH 08/11] quota: Move EXPORT_SYMBOL immediately next to the functions/varibles Jan Kara
2009-01-16 18:08 ` [PATCH 09/11] ext3: Remove unnecessary quota functions Jan Kara
2009-01-16 18:08 ` [PATCH 10/11] ext4: " Jan Kara
2009-01-16 18:08 ` [PATCH 11/11] reiserfs: " Jan Kara
2009-01-20 21:41 ` [PATCH 10/11] ext4: " Mingming Cao
2009-01-20 21:41 ` [PATCH 09/11] ext3: " Mingming Cao
2009-01-24 7:49 ` Andrew Morton [this message]
2009-01-26 10:04 ` [PATCH 01/11] quota: Improve locking Jan Kara
2010-06-22 15:20 ` [RFC][PATCH 00/10] cifs: local caching support using FS-Cache Suresh Jayaraman
2010-06-22 15:22 ` [RFC][PATCH 01/10] cifs: add kernel config option for CIFS Client caching support Suresh Jayaraman
2010-06-22 15:22 ` [RFC][PATCH 02/10] cifs: guard cifsglob.h against multiple inclusion Suresh Jayaraman
[not found] ` <1277220170-3442-1-git-send-email-sjayaraman-l3A5Bk7waGM@public.gmane.org>
2010-06-22 21:37 ` Jeff Layton
2010-06-22 15:23 ` [RFC][PATCH 03/10] cifs: register CIFS for caching Suresh Jayaraman
2010-06-22 15:23 ` [RFC][PATCH 04/10] cifs: define server-level cache index objects and register them with FS-Cache Suresh Jayaraman
[not found] ` <1277220198-3522-1-git-send-email-sjayaraman-l3A5Bk7waGM@public.gmane.org>
2010-06-22 21:52 ` Jeff Layton
[not found] ` <20100622175214.4c56234f-4QP7MXygkU+dMjc06nkz3ljfA9RmPOcC@public.gmane.org>
2010-06-23 5:34 ` Suresh Jayaraman
2010-06-22 15:23 ` [RFC][PATCH 05/10] cifs: define superblock-level cache index objects and register them Suresh Jayaraman
2010-06-22 15:23 ` [RFC][PATCH 06/10] cifs: define inode-level cache object " Suresh Jayaraman
2010-06-22 15:23 ` [RFC][PATCH 07/10] cifs: FS-Cache page management Suresh Jayaraman
2010-06-22 15:24 ` [RFC][PATCH 08/10] cifs: store pages into local cache Suresh Jayaraman
2010-06-22 15:24 ` [RFC][PATCH 09/10] cifs: read pages from FS-Cache Suresh Jayaraman
2010-06-22 15:25 ` [RFC][PATCH 10/10] cifs: add mount option to enable local caching Suresh Jayaraman
2010-06-23 18:32 ` Scott Lovenberg
[not found] ` <4C225338.9010807-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2010-06-25 10:48 ` Suresh Jayaraman
[not found] ` <1277220189-3485-1-git-send-email-sjayaraman-l3A5Bk7waGM@public.gmane.org>
2010-06-23 16:51 ` [RFC][PATCH 03/10] cifs: register CIFS for caching David Howells
[not found] ` <9603.1277311877-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2010-06-25 10:56 ` Suresh Jayaraman
2010-06-23 16:54 ` [RFC][PATCH 04/10] cifs: define server-level cache index objects and register them with FS-Cache David Howells
[not found] ` <1277220206-3559-1-git-send-email-sjayaraman-l3A5Bk7waGM@public.gmane.org>
2010-06-23 16:58 ` [RFC][PATCH 05/10] cifs: define superblock-level cache index objects and register them David Howells
[not found] ` <9720.1277312290-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2010-06-25 12:44 ` Suresh Jayaraman
2010-06-25 12:58 ` David Howells
[not found] ` <22746.1277470713-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2010-06-25 13:26 ` David Howells
[not found] ` <23204.1277472412-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2010-06-28 12:53 ` Suresh Jayaraman
2010-06-28 13:24 ` David Howells
[not found] ` <1277220214-3597-1-git-send-email-sjayaraman-l3A5Bk7waGM@public.gmane.org>
2010-06-23 17:02 ` [RFC][PATCH 06/10] cifs: define inode-level cache object " David Howells
[not found] ` <9822.1277312573-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2010-06-25 12:50 ` Suresh Jayaraman
[not found] ` <4C24A606.5040001-l3A5Bk7waGM@public.gmane.org>
2010-06-25 12:55 ` David Howells
[not found] ` <22697.1277470549-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2010-06-25 16:53 ` Jeff Layton
2010-06-25 21:46 ` David Howells
2010-06-25 22:26 ` Jeff Layton
2010-06-25 23:05 ` Steve French
2010-06-26 0:52 ` Mingming Cao
2010-06-27 18:17 ` Aneesh Kumar K. V
[not found] ` <871vbscpce.fsf-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>
2010-06-27 18:22 ` Christoph Hellwig
[not found] ` <20100625182651.36800d06-9yPaYZwiELC+kQycOl6kW4xkIHaj4LzF@public.gmane.org>
2010-06-25 23:04 ` David Howells
2010-06-23 17:05 ` [RFC][PATCH 07/10] cifs: FS-Cache page management David Howells
[not found] ` <1277220240-3674-1-git-send-email-sjayaraman-l3A5Bk7waGM@public.gmane.org>
2010-06-23 17:06 ` [RFC][PATCH 08/10] cifs: store pages into local cache David Howells
[not found] ` <1277220261-3717-1-git-send-email-sjayaraman-l3A5Bk7waGM@public.gmane.org>
2010-06-23 17:07 ` [RFC][PATCH 09/10] cifs: read pages from FS-Cache David Howells
2010-06-23 17:08 ` [RFC][PATCH 10/10] cifs: add mount option to enable local caching David Howells
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