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. > > http://sourceforge.net/mailarchive/forum.php?thread_name=200708312003.30446.bernd-schubert%40gmx.de&forum_name=nfs > > 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 [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
