lkml.org 
[lkml]   [2010]   [Nov]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Date
    From
    Subject[PATCH 3/5] writeback: stop background/kupdate works from livelocking other works
    From: Jan Kara <jack@suse.cz>

    Background writeback are easily livelockable (from a definition of their
    target). This is inconvenient because it can make sync(1) stall forever waiting
    on its queued work to be finished. Generally, when a flusher thread has
    some work queued, someone submitted the work to achieve a goal more specific
    than what background writeback does. So it makes sense to give it a priority
    over a generic page cleaning.

    Thus we interrupt background writeback if there is some other work to do. We
    return to the background writeback after completing all the queued work.

    Signed-off-by: Jan Kara <jack@suse.cz>
    Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
    ---
    fs/fs-writeback.c | 9 +++++++++
    1 file changed, 9 insertions(+)

    --- linux-next.orig/fs/fs-writeback.c 2010-11-07 21:56:42.000000000 +0800
    +++ linux-next/fs/fs-writeback.c 2010-11-07 22:00:51.000000000 +0800
    @@ -651,6 +651,15 @@ static long wb_writeback(struct bdi_writ
    break;

    /*
    + * Background writeout and kupdate-style writeback are
    + * easily livelockable. Stop them if there is other work
    + * to do so that e.g. sync can proceed.
    + */
    + if ((work->for_background || work->for_kupdate) &&
    + !list_empty(&wb->bdi->work_list))
    + break;
    +
    + /*
    * For background writeout, stop when we are below the
    * background dirty threshold
    */



    \
     
     \ /
      Last update: 2010-11-09 00:27    [W:0.022 / U:0.752 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site