From: Chris Mason <chris.mason@oracle.com>
To: Josef Bacik <josef@redhat.com>
Cc: linux-btrfs@vger.kernel.org
Subject: Re: Allocator changes
Date: Mon, 26 Oct 2009 18:28:01 +0900 [thread overview]
Message-ID: <20091026092801.GD5564@think> (raw)
In-Reply-To: <20091021214135.GA5935@localhost.localdomain>
On Wed, Oct 21, 2009 at 05:41:36PM -0400, Josef Bacik wrote:
> Hello,
>
> I've been thinking recently about how to fix the caching stuff so it isn't so
> damned slow and had started to work on writing out the free space cache into
> bitmaps for every dirty bitmap, but then Eric Sandeen pointed out that xfs just
> has a couple of btree's to track free space, so I started thinking about doing
> it that way, since we do have this nice btree code laying about.
>
> There are a couple of problems with adding another free space root however:
The free space root seems like it will have a pretty high overhead to
me. But, I do like your general idea of caching the free space map at
commit time as an on-disk cache. I think as we nail down the enospc
corners we can go back and give that a try.
To get around the cow problem, we can log the cache to the log tree.
-chris
prev parent reply other threads:[~2009-10-26 9:28 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-10-21 21:41 Allocator changes Josef Bacik
2009-10-22 17:37 ` Josef Bacik
2009-10-26 9:28 ` Chris Mason [this message]
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