On Wed, Apr 26, 2017 at 09:32:19PM +0800, Xiao Ni wrote:
> In new barrier codes, raise_barrier waits if conf->nr_pending[idx] is not zero.
> After all the conditions are true, the resync request can go on be handled. But
> it adds conf->nr_pending[idx] again. The next resync request hit the same bucket
> idx need to wait the resync request which is submitted before. The performance
> of resync/recovery is degraded.
> So we should use a new variable to count sync requests which are in flight.
>
> Suggested-by: Shaohua Li <shli@xxxxxxxxxx>
> Suggested-by: Coly Li <colyli@xxxxxxx>
> Signed-off-by: Xiao Ni <xni@xxxxxxxxxx>
> ---
> drivers/md/raid1.c | 14 +++++++++++---
> drivers/md/raid1.h | 1 +
> 2 files changed, 12 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
> index a34f587..3c304ef 100644
> --- a/drivers/md/raid1.c
> +++ b/drivers/md/raid1.c
> @@ -869,7 +869,7 @@ static void raise_barrier(struct r1conf *conf, sector_t sector_nr)
> atomic_read(&conf->barrier[idx]) < RESYNC_DEPTH,
> conf->resync_lock);
>
> - atomic_inc(&conf->nr_pending[idx]);
> + atomic_inc(&conf->nr_sync_pending[idx]);
Any reason why nr_sync_pending is an array? Looks a single atomic is enough to me.
Thanks,
Shaohua
> spin_unlock_irq(&conf->resync_lock);
> }
>
> @@ -880,7 +880,7 @@ static void lower_barrier(struct r1conf *conf, sector_t sector_nr)
> BUG_ON(atomic_read(&conf->barrier[idx]) <= 0);
>
> atomic_dec(&conf->barrier[idx]);
> - atomic_dec(&conf->nr_pending[idx]);
> + atomic_dec(&conf->nr_sync_pending[idx]);
> wake_up(&conf->wait_barrier);
> }
>
> @@ -1018,7 +1018,8 @@ static int get_unqueued_pending(struct r1conf *conf)
> int idx, ret;
>
> for (ret = 0, idx = 0; idx < BARRIER_BUCKETS_NR; idx++)
> - ret += atomic_read(&conf->nr_pending[idx]) -
> + ret += atomic_read(&conf->nr_pending[idx]) +
> + atomic_read(&conf->nr_sync_pending[idx]) -
> atomic_read(&conf->nr_queued[idx]);
>
> return ret;
> @@ -3024,6 +3025,11 @@ static struct r1conf *setup_conf(struct mddev *mddev)
> if (!conf->nr_pending)
> goto abort;
>
> + conf->nr_sync_pending = kcalloc(BARRIER_BUCKETS_NR,
> + sizeof(atomic_t), GFP_KERNEL);
> + if (!conf->nr_sync_pending)
> + goto abort;
> +
> conf->nr_waiting = kcalloc(BARRIER_BUCKETS_NR,
> sizeof(atomic_t), GFP_KERNEL);
> if (!conf->nr_waiting)
> @@ -3136,6 +3142,7 @@ static struct r1conf *setup_conf(struct mddev *mddev)
> kfree(conf->mirrors);
> safe_put_page(conf->tmppage);
> kfree(conf->poolinfo);
> + kfree(conf->nr_sync_pending);
> kfree(conf->nr_pending);
> kfree(conf->nr_waiting);
> kfree(conf->nr_queued);
> @@ -3241,6 +3248,7 @@ static void raid1_free(struct mddev *mddev, void *priv)
> kfree(conf->mirrors);
> safe_put_page(conf->tmppage);
> kfree(conf->poolinfo);
> + kfree(conf->nr_sync_pending);
> kfree(conf->nr_pending);
> kfree(conf->nr_waiting);
> kfree(conf->nr_queued);
> diff --git a/drivers/md/raid1.h b/drivers/md/raid1.h
> index dd22a37..a3580ee 100644
> --- a/drivers/md/raid1.h
> +++ b/drivers/md/raid1.h
> @@ -85,6 +85,7 @@ struct r1conf {
> wait_queue_head_t wait_barrier;
> spinlock_t resync_lock;
> atomic_t *nr_pending;
> + atomic_t *nr_sync_pending;
> atomic_t *nr_waiting;
> atomic_t *nr_queued;
> atomic_t *barrier;
> --
> 2.7.4
>
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