From: Christoph Hellwig <hch@infradead.org>
To: Dave Chinner <david@fromorbit.com>
Cc: Christoph Hellwig <hch@infradead.org>, xfs@oss.sgi.com
Subject: Re: [PATCH 00/10] remove xfsbufd
Date: Thu, 29 Mar 2012 15:38:43 -0400 [thread overview]
Message-ID: <20120329193843.GA32368@infradead.org> (raw)
In-Reply-To: <20120329005224.GJ5091@dastard>
On Thu, Mar 29, 2012 at 11:52:24AM +1100, Dave Chinner wrote:
> I suspect that this can be done without much API churn, and it would
> remove the central per-AG buffer cache lookups for most operations.
> Smaller caches means less lookup overhead for most operations - with
> 10-11% of CPU time being spent in lookups on an 8p machine, that's
> almost an entire CPU worth of time being used. Hence reducing the
> rbtree lookup and modification overhead should be a significant win.
>
> Crazy idea, yes, but I'm going to think about it some more,
> especially as the shrinker operates of the LRU and is entirely
> independent of the rbtree indexing.....
Sounds like a good idea to me. I think the biggest win will be to index
the directory blocks logically, e.g. have a tree hanging off the inode
to find them. The other worthwhile optimizations besides avoiding AGI buffer
lookups during inode scanning would be to do something more about inode
buffers - probably a tree that maps directly from inode number to the
backing buffer.
I'd probably add the secondary tree linkage directly to the buffer to
keep things simpler. In fact I'm not even sure we need a secondary
linkage - at least from a quick look I can't see why we'd need to keep
buffers on the physically indexed per-ag rbtree if we can find them by
other means.
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prev parent reply other threads:[~2012-03-29 19:38 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-03-27 16:44 [PATCH 00/10] remove xfsbufd Christoph Hellwig
2012-03-27 16:44 ` [PATCH 01/10] xfs: remove log item from AIL in xfs_qm_dqflush after a shutdown Christoph Hellwig
2012-03-27 18:17 ` Mark Tinguely
2012-04-13 9:36 ` Dave Chinner
2012-03-27 16:44 ` [PATCH 02/10] xfs: remove log item from AIL in xfs_iflush " Christoph Hellwig
2012-04-13 9:37 ` Dave Chinner
2012-03-27 16:44 ` [PATCH 03/10] xfs: allow assigning the tail lsn with the AIL lock held Christoph Hellwig
2012-03-27 18:18 ` Mark Tinguely
2012-04-13 9:42 ` Dave Chinner
2012-03-27 16:44 ` [PATCH 04/10] xfs: implement freezing by emptying the AIL Christoph Hellwig
2012-04-13 10:04 ` Dave Chinner
2012-04-16 13:33 ` Mark Tinguely
2012-04-16 13:47 ` Mark Tinguely
2012-04-16 23:54 ` Dave Chinner
2012-04-17 4:20 ` Dave Chinner
2012-04-17 8:26 ` Dave Chinner
2012-04-18 13:13 ` Mark Tinguely
2012-04-18 18:14 ` Ben Myers
2012-04-18 17:53 ` Mark Tinguely
2012-03-27 16:44 ` [PATCH 05/10] xfs: do flush inodes from background inode reclaim Christoph Hellwig
2012-04-13 10:14 ` Dave Chinner
2012-04-16 19:25 ` Mark Tinguely
2012-03-27 16:44 ` [PATCH 06/10] xfs: do not write the buffer from xfs_iflush Christoph Hellwig
2012-04-13 10:31 ` Dave Chinner
2012-04-18 13:33 ` Mark Tinguely
2012-03-27 16:44 ` [PATCH 07/10] xfs: do not write the buffer from xfs_qm_dqflush Christoph Hellwig
2012-04-13 10:33 ` Dave Chinner
2012-04-18 21:11 ` Mark Tinguely
2012-03-27 16:44 ` [PATCH 08/10] xfs: do not add buffers to the delwri queue until pushed Christoph Hellwig
2012-04-13 10:35 ` Dave Chinner
2012-04-18 21:11 ` Mark Tinguely
2012-03-27 16:44 ` [PATCH 09/10] xfs: on-stack delayed write buffer lists Christoph Hellwig
2012-04-13 11:37 ` Dave Chinner
2012-04-20 18:19 ` Mark Tinguely
2012-04-21 0:42 ` Dave Chinner
2012-04-23 1:57 ` Dave Chinner
2012-03-27 16:44 ` [PATCH 10/10] xfs: remove some obsolete comments in xfs_trans_ail.c Christoph Hellwig
2012-04-13 11:37 ` Dave Chinner
2012-03-28 0:53 ` [PATCH 00/10] remove xfsbufd Dave Chinner
2012-03-28 15:10 ` Christoph Hellwig
2012-03-29 0:52 ` Dave Chinner
2012-03-29 19:38 ` Christoph Hellwig [this message]
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