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    SubjectRe: patch: improve generic_file_buffered_write() (2nd try 1/2)
    Nick Piggin <> writes:

    > Anyway, there are fixes for this deadlock in Andrew's -mm tree, but
    > also a workaround for the NFSD problem in git commit 29dbb3fc. Did
    > you try a later kernel to see if it is fixed there?

    I had a chance to look up that commit (git clone took a while so sorry
    for writing 2 mails). It is present in 2.6.23-rc5 so I already noticed
    it when merging our patch in 2.6.23-rc5.

    Upon closer reading of the patch though I see that it will indeed
    prevent writes by the nfsd to be split smaller than PAGE_SIZE and it
    will cause filemap_copy_from_user[_iovec] to be called with a source
    spanning multiple pages.

    So the commit 29dbb3fc should have a simmilar, slightly better even,
    gain for the nfsd and other kernel space segments. But it will not
    improve writes from user space, where ~14% of the commits were saved
    during a days work for me.

    Now I have a question about fault_in_pages_readable(). Can I call that
    for multiple pages and then call __grab_cache_page() without risking
    one of the pages from getting lost again and causing a deadlock?

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      Last update: 2007-09-07 23:03    [W:0.020 / U:45.920 seconds]
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