From: Christoph Hellwig <hch@infradead.org>
To: Michael Monnerie <michael.monnerie@is.it-management.at>
Cc: Christoph Hellwig <hch@infradead.org>,
Lukas Czerner <lczerner@redhat.com>,
xfs@oss.sgi.com
Subject: Re: xfs: add FITRIM support
Date: Thu, 6 Jan 2011 13:06:03 -0500 [thread overview]
Message-ID: <20110106180603.GB32670@infradead.org> (raw)
In-Reply-To: <201101052307.38379@zmi.at>
On Wed, Jan 05, 2011 at 11:07:35PM +0100, Michael Monnerie wrote:
> On Mittwoch, 5. Januar 2011 Lukas Czerner wrote:
> > If we
> > notice that we are running out of space in advance (how much in
> > advance?), we can start trimming smaller chunks, until we reach
> > reasonable a reasonable pool of reclaimed space, or until we trim
> > the whole device.
>
> Would it be possible that all blocks that have been in use since the
> last FITRIM run can be logged?
It's a lot of overhead for the big hammer approach the FITRIM is. If
you're interested look for some of my earlier discard support patches
as they implemented it using an rbtree. But getting this fully right
just was a lot of overhead. My strategy is to instead have the simple
big hammer FITRIM for e.g. people that want to reclaim storage from a
VM or thing provisioned array once in a while, while implementing an
optimized discard on commit for SSDs. I'm planning to have the latter
ready for 2.6.39. The biggest part to get it is to avoid allocating
extents from busy ranges, and I've finally got an older patch from Dave
to fully work for that. The next step is to have proper asynchronous
discard requests to avoid the waiting overhead the other filesystems
have right now.
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prev parent reply other threads:[~2011-01-06 18:03 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-11-25 11:23 xfs: add FITRIM support Christoph Hellwig
2010-12-22 21:41 ` Alex Elder
2010-12-28 16:09 ` Christoph Hellwig
2011-01-03 10:49 ` Lukas Czerner
2010-12-23 1:44 ` Dave Chinner
2010-12-30 11:41 ` Christoph Hellwig
2011-01-03 10:57 ` Lukas Czerner
2011-01-03 23:25 ` Dave Chinner
2011-01-05 10:21 ` Lukas Czerner
2011-01-05 22:07 ` Michael Monnerie
2011-01-05 22:50 ` Dave Chinner
2011-01-06 8:10 ` Michael Monnerie
2011-01-06 8:33 ` Lukas Czerner
2011-01-06 8:40 ` Lukas Czerner
2011-01-06 9:17 ` Dave Chinner
2011-01-06 16:50 ` Michael Monnerie
2011-01-06 18:10 ` Christoph Hellwig
2011-01-06 18:08 ` Christoph Hellwig
2011-01-06 18:06 ` Christoph Hellwig [this message]
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