From: Joe Thornber Date: Fri, 12 Sep 2014 10:34:01 +0000 (+0100) Subject: dm thin: performance improvement to discard processing X-Git-Url: http://git.cdn.openwrt.org/?a=commitdiff_plain;h=7a7e97ca580b944d2c89b59bc74a7b9ddd044705;p=openwrt%2Fstaging%2Fblogic.git dm thin: performance improvement to discard processing When processing a discard bio, if the block is already quiesced do the discard immediately rather than adding the mapping to a list for the next iteration of the worker thread. Discarding a fully provisioned 100G thin volume with 64k block size goes from 860s to 95s with this change. Clearly there's something wrong with the worker architecture, more investigation needed. Signed-off-by: Joe Thornber Signed-off-by: Mike Snitzer --- diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c index 068607828691..8c3d048dd319 100644 --- a/drivers/md/dm-thin.c +++ b/drivers/md/dm-thin.c @@ -1194,7 +1194,6 @@ static void retry_bios_on_resume(struct pool *pool, struct dm_bio_prison_cell *c static void process_discard(struct thin_c *tc, struct bio *bio) { int r; - unsigned long flags; struct pool *pool = tc->pool; struct dm_bio_prison_cell *cell, *cell2; struct dm_cell_key key, key2; @@ -1235,12 +1234,9 @@ static void process_discard(struct thin_c *tc, struct bio *bio) m->cell2 = cell2; m->bio = bio; - if (!dm_deferred_set_add_work(pool->all_io_ds, &m->list)) { - spin_lock_irqsave(&pool->lock, flags); - list_add_tail(&m->list, &pool->prepared_discards); - spin_unlock_irqrestore(&pool->lock, flags); - wake_worker(pool); - } + if (!dm_deferred_set_add_work(pool->all_io_ds, &m->list)) + pool->process_prepared_discard(m); + } else { inc_all_io_entry(pool, bio); cell_defer_no_holder(tc, cell);