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From: Alex Elder <aelder@sgi.com>
To: Dave Chinner <david@fromorbit.com>
Cc: xfs@oss.sgi.com
Subject: Re: [PATCH 04/18] xfs: lockless per-ag lookups
Date: Tue, 14 Sep 2010 12:28:47 -0500	[thread overview]
Message-ID: <1284485327.2098.81.camel@doink> (raw)
In-Reply-To: <1284461777-1496-5-git-send-email-david@fromorbit.com>

On Tue, 2010-09-14 at 20:56 +1000, Dave Chinner wrote:
> From: Dave Chinner <dchinner@redhat.com>
> 
> When we start taking a reference to the per-ag for every cached
> buffer in the system, kernel lockstat profiling on an 8-way create
> workload shows the mp->m_perag_lock has higher acquisition rates
> than the inode lock and has significantly more contention. That is,
> it becomes the highest contended lock in the system.
> 
> The perag lookup is trivial to convert to lock-less RCU lookups
> because perag structures never go away. Hence the only thing we need
> to protect against is tree structure changes during a grow. THis can
> be done simply by replacing the locking in xfs_perag_get() with RCU
> read locking. This removes the mp->m_perag_lock completely from this
> path.

Nice.

Reviewed-by: Alex Elder <aelder@sgi.com>

> Signed-off-by: Dave Chinner <dchinner@redhat.com>
> ---
>  fs/xfs/xfs_ag.h    |    3 +++
>  fs/xfs/xfs_mount.c |   25 +++++++++++++++++--------
>  2 files changed, 20 insertions(+), 8 deletions(-)


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  parent reply	other threads:[~2010-09-14 17:28 UTC|newest]

Thread overview: 69+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-09-14 10:55 [PATCH 0/18] xfs: metadata and buffer cache scalability improvements Dave Chinner
2010-09-14 10:56 ` [PATCH 01/18] xfs: single thread inode cache shrinking Dave Chinner
2010-09-14 18:48   ` Alex Elder
2010-09-14 22:48     ` Dave Chinner
2010-09-14 10:56 ` [PATCH 02/18] xfs: reduce the number of CIL lock round trips during commit Dave Chinner
2010-09-14 14:48   ` Christoph Hellwig
2010-09-14 17:21   ` Alex Elder
2010-09-14 10:56 ` [PATCH 03/18] xfs: remove debug assert for per-ag reference counting Dave Chinner
2010-09-14 14:48   ` Christoph Hellwig
2010-09-14 17:22   ` Alex Elder
2010-09-14 10:56 ` [PATCH 04/18] xfs: lockless per-ag lookups Dave Chinner
2010-09-14 12:35   ` Dave Chinner
2010-09-14 14:50   ` Christoph Hellwig
2010-09-14 17:28   ` Alex Elder [this message]
2010-09-14 10:56 ` [PATCH 05/18] xfs: convert inode cache lookups to use RCU locking Dave Chinner
2010-09-14 16:27   ` Christoph Hellwig
2010-09-14 23:17     ` Dave Chinner
2010-09-14 21:23   ` Alex Elder
2010-09-14 23:42     ` Dave Chinner
2010-09-14 10:56 ` [PATCH 06/18] xfs: convert pag_ici_lock to a spin lock Dave Chinner
2010-09-14 21:26   ` Alex Elder
2010-09-14 10:56 ` [PATCH 07/18] xfs: don't use vfs writeback for pure metadata modifications Dave Chinner
2010-09-14 14:54   ` Christoph Hellwig
2010-09-15  0:14     ` Dave Chinner
2010-09-15  0:17       ` Christoph Hellwig
2010-09-14 22:12   ` Alex Elder
2010-09-15  0:28     ` Dave Chinner
2010-11-08 10:47   ` Christoph Hellwig
2010-09-14 10:56 ` [PATCH 08/18] xfs: rename xfs_buf_get_nodaddr to be more appropriate Dave Chinner
2010-09-14 14:56   ` Christoph Hellwig
2010-09-14 22:14   ` Alex Elder
2010-09-14 10:56 ` [PATCH 09/18] xfs: introduced uncached buffer read primitve Dave Chinner
2010-09-14 14:56   ` Christoph Hellwig
2010-09-14 22:16   ` Alex Elder
2010-09-14 10:56 ` [PATCH 10/18] xfs: store xfs_mount in the buftarg instead of in the xfs_buf Dave Chinner
2010-09-14 14:57   ` Christoph Hellwig
2010-09-14 22:21   ` Alex Elder
2010-09-14 10:56 ` [PATCH 11/18] xfs: kill XBF_FS_MANAGED buffers Dave Chinner
2010-09-14 14:59   ` Christoph Hellwig
2010-09-14 22:26   ` Alex Elder
2010-09-14 10:56 ` [PATCH 12/18] xfs: use unhashed buffers for size checks Dave Chinner
2010-09-14 15:00   ` Christoph Hellwig
2010-09-14 22:29   ` Alex Elder
2010-09-14 10:56 ` [PATCH 13/18] xfs: remove buftarg hash for external devices Dave Chinner
2010-09-14 22:29   ` Alex Elder
2010-09-14 10:56 ` [PATCH 14/18] xfs: convert buffer cache hash to rbtree Dave Chinner
2010-09-14 16:29   ` Christoph Hellwig
2010-09-15 17:46   ` Alex Elder
2010-09-14 10:56 ` [PATCH 15/18] xfs; pack xfs_buf structure more tightly Dave Chinner
2010-09-14 16:30   ` Christoph Hellwig
2010-09-15 18:01   ` Alex Elder
2010-09-14 10:56 ` [PATCH 16/18] xfs: convert xfsbud shrinker to a per-buftarg shrinker Dave Chinner
2010-09-14 16:32   ` Christoph Hellwig
2010-09-15 20:19   ` Alex Elder
2010-09-16  0:28     ` Dave Chinner
2010-09-14 10:56 ` [PATCH 17/18] xfs: add a lru to the XFS buffer cache Dave Chinner
2010-09-14 23:16   ` Christoph Hellwig
2010-09-15  0:05     ` Dave Chinner
2010-09-15 21:28   ` Alex Elder
2010-09-14 10:56 ` [PATCH 18/18] xfs: stop using the page cache to back the " Dave Chinner
2010-09-14 23:20   ` Christoph Hellwig
2010-09-15  0:06     ` Dave Chinner
2010-09-14 14:25 ` [PATCH 0/18] xfs: metadata and buffer cache scalability improvements Christoph Hellwig
2010-09-17 13:21 ` Alex Elder
2010-09-21  2:02   ` Dave Chinner
2010-09-21 16:23     ` Alex Elder
2010-09-21 22:34       ` Dave Chinner
  -- strict thread matches above, loose matches on Subject: below --
2010-09-24 12:30 [PATCH 0/18] xfs: metadata scalability V3 Dave Chinner
2010-09-24 12:31 ` [PATCH 04/18] xfs: lockless per-ag lookups Dave Chinner
2010-09-27  1:47 [PATCH 0/18] xfs: metadata scalability V4 Dave Chinner
2010-09-27  1:47 ` [PATCH 04/18] xfs: lockless per-ag lookups Dave Chinner

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