From: Dave Chinner <david@fromorbit.com>
To: Al Viro <viro@ZenIV.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, xfs@oss.sgi.com
Subject: Re: [PATCH 06/12] inode: Make unused inode LRU per superblock
Date: Sat, 4 Jun 2011 11:40:13 +1000 [thread overview]
Message-ID: <20110604014013.GC561@dastard> (raw)
In-Reply-To: <20110604002552.GU11521@ZenIV.linux.org.uk>
On Sat, Jun 04, 2011 at 01:25:52AM +0100, Al Viro wrote:
> On Thu, Jun 02, 2011 at 05:01:01PM +1000, Dave Chinner wrote:
> > From: Dave Chinner <dchinner@redhat.com>
> >
> > The inode unused list is currently a global LRU. This does not match
> > the other global filesystem cache - the dentry cache - which uses
> > per-superblock LRU lists. Hence we have related filesystem object
> > types using different LRU reclaimation schemes.
> >
> > To enable a per-superblock filesystem cache shrinker, both of these
> > caches need to have per-sb unused object LRU lists. Hence this patch
> > converts the global inode LRU to per-sb LRUs.
> >
> > The patch only does rudimentary per-sb propotioning in the shrinker
> > infrastructure, as this gets removed when the per-sb shrinker
> > callouts are introduced later on.
>
> What protects s_nr_inodes_unused?
For this patch, the modifications are protected by the
inode_lru_lock, but the reads are unprotected. That's the same
protection as the inode_stat.nr_unused field, and the same as the
existing dentry cache per-sb LRU accounting. In the next patch
modifcations are moved under the sb->s_inode_lru_lock, but reads
still remain unprotected.
I can see how the multiple reads in shrink_icache_sb() could each
return a different value during the proportioning, but I don't think
that is a big problem. That proportioning code goes away in the next
patch and is replaced by different code in prune_super(), so if you
want the reads protected by locks or a single snapshot used for the
proportioning calculations I'll do it in the new code in
prune_super().
Cheers,
Dave.
--
Dave Chinner
david@fromorbit.com
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next prev parent reply other threads:[~2011-06-04 1:40 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-06-02 7:00 [PATCH 0/12] Per superblock cache reclaim Dave Chinner
2011-06-02 7:00 ` [PATCH 01/12] vmscan: add shrink_slab tracepoints Dave Chinner
2011-06-20 0:44 ` KOSAKI Motohiro
2011-06-20 0:53 ` Dave Chinner
2011-06-02 7:00 ` [PATCH 02/12] vmscan: shrinker->nr updates race and go wrong Dave Chinner
2011-06-20 0:46 ` KOSAKI Motohiro
2011-06-20 1:25 ` Dave Chinner
2011-06-20 4:30 ` KOSAKI Motohiro
2011-06-02 7:00 ` [PATCH 03/12] vmscan: reduce wind up shrinker->nr when shrinker can't do work Dave Chinner
2011-06-20 0:51 ` KOSAKI Motohiro
2011-06-21 5:09 ` Dave Chinner
2011-06-21 5:27 ` KOSAKI Motohiro
2011-06-02 7:00 ` [PATCH 04/12] vmscan: add customisable shrinker batch size Dave Chinner
2011-06-02 7:01 ` [PATCH 05/12] inode: convert inode_stat.nr_unused to per-cpu counters Dave Chinner
2011-06-02 7:01 ` [PATCH 06/12] inode: Make unused inode LRU per superblock Dave Chinner
2011-06-04 0:25 ` Al Viro
2011-06-04 1:40 ` Dave Chinner [this message]
2011-06-02 7:01 ` [PATCH 07/12] inode: move to per-sb LRU locks Dave Chinner
2011-06-02 7:01 ` [PATCH 08/12] superblock: introduce per-sb cache shrinker infrastructure Dave Chinner
2011-06-04 0:42 ` Al Viro
2011-06-04 1:52 ` Dave Chinner
2011-06-04 14:08 ` Christoph Hellwig
2011-06-04 14:19 ` Al Viro
2011-06-04 14:24 ` Al Viro
2011-06-02 7:01 ` [PATCH 09/12] inode: remove iprune_sem Dave Chinner
2011-06-02 7:01 ` [PATCH 10/12] superblock: add filesystem shrinker operations Dave Chinner
2011-06-02 7:01 ` [PATCH 11/12] vfs: increase shrinker batch size Dave Chinner
2011-06-02 9:30 ` Nicolas Kaiser
2011-06-02 7:01 ` [PATCH 12/12] xfs: make use of new shrinker callout for the inode cache Dave Chinner
2011-06-16 11:33 ` [PATCH 0/12] Per superblock cache reclaim Christoph Hellwig
2011-06-17 3:35 ` KOSAKI Motohiro
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