lustre/kernel_patches/patches/raid5-large-io.patch

   1 This patch changes max request size to <chunk size> * <disks>
   2 in order to allow Lustre to submit large I/Os and avoid
   3 unnecessary reads.
   4
   5 Index: linux-2.6.9/drivers/md/raid5.c
   6 ===================================================================
   7 --- linux-2.6.9.orig/drivers/md/raid5.c 2006-05-22 00:01:30.000000000 +0400
   8 +++ linux-2.6.9/drivers/md/raid5.c      2006-05-22 00:09:56.000000000 +0400
   9 @@ -1609,6 +1609,11 @@ static int run (mddev_t *mddev)
  10         mddev->queue->unplug_fn = raid5_unplug_device;
  11         mddev->queue->issue_flush_fn = raid5_issue_flush;
  12
  13 +       /* in order to support large I/Os */
  14 +       blk_queue_max_sectors(mddev->queue, mddev->chunk_size * mddev->raid_disks >> 9);
  15 +       mddev->queue->max_phys_segments = mddev->chunk_size * mddev->raid_disks >> PAGE_SHIFT;
  16 +       mddev->queue->max_hw_segments = mddev->chunk_size * mddev->raid_disks >> PAGE_SHIFT;;
  17 +
  18         PRINTK("raid5: run(%s) called.\n", mdname(mddev));
  19
  20         ITERATE_RDEV(mddev,rdev,tmp) {