lustre/kernel_patches/patches/raid5-configurable-cachesize.patch

   1 Adds a module parameter to control raid5's internal cache size.
   2
   3 Index: linux-2.6.9/drivers/md/raid5.c
   4 ===================================================================
   5 --- linux-2.6.9.orig/drivers/md/raid5.c 2006-05-21 17:57:25.000000000 +0400
   6 +++ linux-2.6.9/drivers/md/raid5.c      2006-05-22 00:01:30.000000000 +0400
   7 @@ -28,7 +28,8 @@
   8   * Stripe cache
   9   */
  10
  11 -#define NR_STRIPES             256
  12 +static int raid5_nr_stripes = 256 * 8;
  13 +
  14  #define STRIPE_SIZE            PAGE_SIZE
  15  #define STRIPE_SHIFT           (PAGE_SHIFT - 9)
  16  #define STRIPE_SECTORS         (STRIPE_SIZE>>9)
  17 @@ -92,7 +93,7 @@ static inline void __release_stripe(raid
  18                         list_add_tail(&sh->lru, &conf->inactive_list);
  19                         atomic_dec(&conf->active_stripes);
  20                         if (!conf->inactive_blocked ||
  21 -                           atomic_read(&conf->active_stripes) < (NR_STRIPES*3/4))
  22 +                           atomic_read(&conf->active_stripes) < (conf->max_nr_stripes*3/4))
  23                                 wake_up(&conf->wait_for_stripe);
  24                 }
  25         }
  26 @@ -255,7 +256,7 @@ static struct stripe_head *get_active_st
  27                                 conf->inactive_blocked = 1;
  28                                 wait_event_lock_irq(conf->wait_for_stripe,
  29                                                     !list_empty(&conf->inactive_list) &&
  30 -                                                   (atomic_read(&conf->active_stripes) < (NR_STRIPES *3/4)
  31 +                                                   (atomic_read(&conf->active_stripes) < (conf->max_nr_stripes *3/4)
  32                                                      || !conf->inactive_blocked),
  33                                                     conf->device_lock,
  34                                                     unplug_slaves(conf->mddev);
  35 @@ -1637,7 +1638,7 @@ static int run (mddev_t *mddev)
  36         conf->chunk_size = mddev->chunk_size;
  37         conf->level = mddev->level;
  38         conf->algorithm = mddev->layout;
  39 -       conf->max_nr_stripes = NR_STRIPES;
  40 +       conf->max_nr_stripes = raid5_nr_stripes;
  41
  42         /* device size must be a multiple of chunk size */
  43         mddev->size &= ~(mddev->chunk_size/1024 -1);
  44 @@ -1957,5 +1958,6 @@ static void raid5_exit (void)
  45
  46  module_init(raid5_init);
  47  module_exit(raid5_exit);
  48 +module_param(raid5_nr_stripes, int, 0644);
  49  MODULE_LICENSE("GPL");
  50  MODULE_ALIAS("md-personality-4"); /* RAID5 */