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    SubjectRe: [RFC] Heads up on sys_fallocate()
    On Tue 06-03-07 06:36:09, Ulrich Drepper wrote:
    > Christoph Hellwig wrote:
    > > fallocate with the whence argument and flags is already quite complicated,
    > > I'd rather have another call for placement decisions, that would
    > > be called on an fd to do placement decissions for any further allocations
    > > (prealloc, write, etc)
    >
    > Yes, posix_fallocate shouldn't be made more complicated. But I don't
    > understand why requesting linear layout of the blocks should be an
    > option. It's always an advantage if the blocks requested this way are
    > linear on disk. So, the kernel should always do its best to make this
    > happen, without needing an additional option.
    Actually, it's not that simple. You want linear layout of blocks you are
    going to read. That is not necessary a linear layout of blocks in a single
    file - trace sometime a start of some complicated app like KDE. You find
    it's seeking like a hell because it needs a few blocks from a ton of
    distinct files (shared libs, config files, etc). As these files are mostly
    read only, it's advantageous to interleave them on disk or at least keep
    them close.

    Honza
    --
    Jan Kara <jack@suse.cz>
    SuSE CR Labs
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