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    SubjectRe: stat benchmark
    Theodore Tso wrote:
    >> Aside from what has already been proposed there is also the
    >> readdirplus() route. Unfortunately the people behind this and related
    >> proposals vanished after the last discussions. I was hoping they
    >> come back with a revised proposal but perhaps not. Maybe it's time to
    >> pick up the ball myself.
    >> As a reminder, readdirplus() is an extended readdir() which also
    >> returns (a subset of) the stat information for the file at the same
    >> time. The subset part is needed to account for the different
    >> information contained in the inodes. For most applications the subset
    >> should be sufficient and therefore all that's needed is a single
    >> iteration over the directory.
    > I'm not sure this would help in the cold cache case, which is what
    > Soeren originally complained about.[1] The problem is whaever
    > information the user might need won't be store in the directory, so
    > the filesystem would end having to stat the file anyway, incurring a
    > disk seek, which was what the user was complaining about. A
    > readdirplus() would save a whole bunch of system calls if the inode
    > was already cached, yes, but I'm not sure that's it would be worth the
    > effort given how small Linux's system call overhead would be. But in
    > the cold cache case, you end up seeking all over the disk, and the
    > only thing you can do is to try to keep the inodes close to each
    > other, and to have either readdir() or the caller of readdir() sort
    > all of the returned directory entries by inode number to avoid seeking
    > all over the disk.

    A readdirplus() could sort the inodes according to the filesystem's
    layout, and additionally issue the stats in parallel, so if you have
    multiple spindles you get significant additional speedup.

    error compiling committee.c: too many arguments to function

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