On Mon, 25 Jun 2012 15:24:56 +0800 Shaohua Li <shli@xxxxxxxxxx> wrote:
> 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);
>
>
I've applied this patch, thanks.
NeilBrown
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