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    SubjectRe: Directories > 2GB
    Hi Dave,

    My recollection is that it used to default to on, it was disabled
    because it needs to map the buffer into a single contiguous chunk
    of kernel memory. This was placing a lot of pressure on the memory
    remapping code, so we made it not default to on as reworking the
    code to deal with non contig memory was looking like a major
    effort.

    Steve


    David Chinner wrote:
    > On Mon, Oct 09, 2006 at 04:53:02PM -0500, Steve Lord wrote:
    >> You might want to think about keeping the directory a little
    >> more contiguous than individual disk blocks. XFS does have
    >> code in it to allocate the directory in chunks larger than
    >> a single file system block. It does not get used on linux
    >> because the code was written under the assumption you can
    >> see the whole chunk as a single piece of memory which does not
    >> work to well in the linux kernel.
    >
    > This code is enabled and seems to work in Linux. I don't know if it
    > passes xfsqa so I don't know how reliable this feature is. TO check
    > it all I did was run a quick test on a x86_64 kernel (4k page
    > size) using 16k directory blocks (4 pages):



    >
    > # mkfs.xfs -f -n size=16384 /dev/ubd/1
    > .....
    > # xfs_db -r -c "sb 0" -c "p dirblklog" /dev/ubd/1
    > dirblklog = 2
    > # mount /dev/ubd/1 /mnt/xfs
    > # for i in `seq 0 1 100000`; do touch fred.$i; done
    > # umount /mnt/xfs
    > # mount /mnt/xfs
    > # ls /mnt/xfs |wc -l
    > 100000
    > # rm -rf /mnt/xfs/*
    > # ls /mnt/xfs |wc -l
    > 0
    > # umount /mnt/xfs
    > #
    >
    > Cheers,
    >
    > Dave.

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