Let raid5d handle stripe in batch way to reduce conf->device_lock locking.
Signed-off-by: Shaohua Li <shli@xxxxxxxxxxxx>
---
drivers/md/raid5.c | 45 ++++++++++++++++++++++++++++++++-------------
1 file changed, 32 insertions(+), 13 deletions(-)
Index: linux/drivers/md/raid5.c
===================================================================
--- linux.orig/drivers/md/raid5.c 2012-06-25 14:38:37.378835415 +0800
+++ linux/drivers/md/raid5.c 2012-06-25 14:38:40.150800523 +0800
@@ -4568,6 +4568,30 @@ static int retry_aligned_read(struct r5
return handled;
}
+#define MAX_STRIPE_BATCH 8
+static int handle_active_stripes(struct r5conf *conf)
+{
+ struct stripe_head *batch[MAX_STRIPE_BATCH], *sh;
+ int i, batch_size = 0;
+
+ while (batch_size < MAX_STRIPE_BATCH &&
+ (sh = __get_priority_stripe(conf)) != NULL)
+ batch[batch_size++] = sh;
+
+ if (batch_size == 0)
+ return batch_size;
+ spin_unlock_irq(&conf->device_lock);
+
+ for (i = 0; i < batch_size; i++)
+ handle_stripe(batch[i]);
+
+ cond_resched();
+
+ spin_lock_irq(&conf->device_lock);
+ for (i = 0; i < batch_size; i++)
+ __release_stripe(conf, batch[i]);
+ return batch_size;
+}
/*
* This is our raid5 kernel thread.
@@ -4578,7 +4602,6 @@ static int retry_aligned_read(struct r5
*/
static void raid5d(struct mddev *mddev)
{
- struct stripe_head *sh;
struct r5conf *conf = mddev->private;
int handled;
struct blk_plug plug;
@@ -4592,6 +4615,7 @@ static void raid5d(struct mddev *mddev)
spin_lock_irq(&conf->device_lock);
while (1) {
struct bio *bio;
+ int batch_size;
if (atomic_read(&mddev->plug_cnt) == 0 &&
!list_empty(&conf->bitmap_list)) {
@@ -4616,21 +4640,16 @@ static void raid5d(struct mddev *mddev)
handled++;
}
- sh = __get_priority_stripe(conf);
-
- if (!sh)
+ batch_size = handle_active_stripes(conf);
+ if (!batch_size)
break;
- spin_unlock_irq(&conf->device_lock);
-
- handled++;
- handle_stripe(sh);
- release_stripe(sh);
- cond_resched();
+ handled += batch_size;
- if (mddev->flags & ~(1<<MD_CHANGE_PENDING))
+ if (mddev->flags & ~(1<<MD_CHANGE_PENDING)) {
+ spin_unlock_irq(&conf->device_lock);
md_check_recovery(mddev);
-
- spin_lock_irq(&conf->device_lock);
+ spin_lock_irq(&conf->device_lock);
+ }
}
pr_debug("%d stripes handled\n", handled);
--
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