[lkml]   [2007]   [Sep]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
    SubjectRe: [PATCH 1/2][RESEND] improve generic_file_buffered_write()
    On Fri, Sep 07, 2007 at 08:52:38PM +0200, Bernd Schubert wrote:
    > No further response to our patches yet, so we are sending them again,
    > re-diffed against 2.6.23-rc5
    > Hi,
    > recently we discovered writing to a nfs-exported lustre filesystem is rather
    > slow (20-40 MB/s writing, but over 200 MB/s reading).
    > As I already explained on the nfs mailing list, this happens since there is an
    > offset on the very first page due to the nfs header.
    > While this especially effects lustre, Olaf Kirch also noticed it on another
    > filesystem before and wrote a nfs patch for it. This patch has two
    > disadvantages - it requires to move all data within the pages, IMHO rather
    > cpu time consuming, furthermore, it presently causes data corruption when
    > more than one nfs thread is running.
    > After thinking it over and over again we (Goswin and I) believe it would be
    > best to improve generic_file_buffered_write().
    > If there is sufficient data now, as it is usual for aio writes,
    > generic_file_buffered_write() will now fill each page as much as possible and
    > only then prepare/commit it. Before generic_file_buffered_write() commited
    > chunks of pages even though there were still more data.

    While the idea is sound in general the code your touching is almost entirely
    gone in -mm and hopefully in 2.6.24. Can you take a look at the Nick's changes
    in -mm that introduce begin_write and end_write methods replacing prepare_write
    and commit_write and see if they improve your situation already. If not they
    should at least provide a framework to deal with it in a slightly cleaner way.

    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to
    More majordomo info at
    Please read the FAQ at

     \ /
      Last update: 2007-09-07 21:41    [W:0.036 / U:18.724 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site