From: Andreas Dilger <adilger@clusterfs.com>
To: Theodore Ts'o <tytso@mit.edu>
Cc: linux-ext4@vger.kernel.org, Alex Tomas <alex@clusterfs.com>
Subject: Re: Design alternatives for fragments/file tail support in ext4
Date: Fri, 13 Oct 2006 02:10:02 -0600 [thread overview]
Message-ID: <20061013081002.GR6221@schatzie.adilger.int> (raw)
In-Reply-To: <E1GXeYv-0006rP-RV@candygram.thunk.org>
On Oct 11, 2006 09:55 -0400, Theodore Ts'o wrote:
> Block allocation clusters
> =========================
> The basic idea is that we store in the superblock the size of a block
> allocation cluster, and that we change the allocation algorithm and the
> preallocation code to always try to allocate blocks so that whenever
> possible, an inode will use contiguous clusters of blocks, which are
> aligned in multiples of the cluster size.
As mentioned in the weekly conference call - Alex has already implemented
this as part of the mballoc code that CFS uses in conjunction with extents.
There is a /proc tunable for the cluster size, which currently defaults to
1MB clusters (the Lustre RPC size) to optimize performance for RAID systems.
The allocations are aligned with the LUN so that an integer number of RAID
stripes are modified for a write. Smaller allocation chunks are packed
together.
Alex is working to update the multi-block allocator for the 2.6.18 kernel,
in conjunction with delayed allocation for ext4, and will hopefully have
a patch soon.
Cheers, Andreas
--
Andreas Dilger
Principal Software Engineer
Cluster File Systems, Inc.
next prev parent reply other threads:[~2006-10-13 8:10 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-10-11 13:55 Design alternatives for fragments/file tail support in ext4 Theodore Ts'o
2006-10-13 6:19 ` Michael Burschik
2006-10-13 8:10 ` Andreas Dilger [this message]
2006-10-13 10:49 ` Theodore Tso
2006-10-13 10:56 ` Alex Tomas
2006-10-13 12:23 ` Theodore Tso
2006-10-13 17:47 ` Andreas Dilger
2006-10-13 12:48 ` Erik Mouw
2006-12-02 11:02 ` Alex Tomas
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