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    SubjectRe: [PATCH] ext2: avoid needless discard of preallocated blocks
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    On Sun, 2006-08-20 at 12:48 +0100, Ron Yorston wrote:
    > Andrew Morton <akpm@osdl.org> wrote:
    > >Been there, done that. The problem was that hanging onto the preallocation
    > >will cause separate files to have up-to-seven-block gaps between them. So
    > >if you put a large number of small files in the same directory, the time to
    > >read them all back is quite significantly impacted: they cover a lot more
    > >disk.
    >
    > The preallocation is only held while the file is open, so there will only
    > be gaps between files that are open simultaneously. If they're created
    > sequentially there will be no gap.
    >
    > This issue exists even with the current code.
    >
    > The patch will have a small effect. With the current code an open file
    > will lose its preallocation when some other process touches the inode.
    > In that case a subsequently created file will follow without a gap. As
    > soon as the open file is written to, though, it gets a new preallocation.
    > -

    maybe porting the reservation code to ext2 (as Val has done) is a nicer
    long term solution..

    --
    if you want to mail me at work (you don't), use arjan (at) linux.intel.com

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