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authorMike Snitzer <snitzer@redhat.com>2015-03-08 08:51:47 +0300
committerMike Snitzer <snitzer@redhat.com>2015-04-15 19:10:16 +0300
commitbfebd1cdb497a57757c83f5fbf1a29931591e2a4 (patch)
treec4ca9675ad22a45eb6e36b130db0d65d574dd2b3 /drivers/md/dm-table.c
parent0ce65797a77ee780f62909d3128bf08b9735718b (diff)
downloadlinux-bfebd1cdb497a57757c83f5fbf1a29931591e2a4.tar.xz
dm: add full blk-mq support to request-based DM
Commit e5863d9ad ("dm: allocate requests in target when stacking on blk-mq devices") served as the first step toward fully utilizing blk-mq in request-based DM -- it enabled stacking an old-style (request_fn) request_queue ontop of the underlying blk-mq device(s). That first step didn't improve performance of DM multipath ontop of fast blk-mq devices (e.g. NVMe) because the top-level old-style request_queue was severely limited by the queue_lock. The second step offered here enables stacking a blk-mq request_queue ontop of the underlying blk-mq device(s). This unlocks significant performance gains on fast blk-mq devices, Keith Busch tested on his NVMe testbed and offered this really positive news: "Just providing a performance update. All my fio tests are getting roughly equal performance whether accessed through the raw block device or the multipath device mapper (~470k IOPS). I could only push ~20% of the raw iops through dm before this conversion, so this latest tree is looking really solid from a performance standpoint." Signed-off-by: Mike Snitzer <snitzer@redhat.com> Tested-by: Keith Busch <keith.busch@intel.com>
Diffstat (limited to 'drivers/md/dm-table.c')
-rw-r--r--drivers/md/dm-table.c11
1 files changed, 8 insertions, 3 deletions
diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index 057312048b68..66600cab9fa5 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -18,6 +18,7 @@
#include <linux/mutex.h>
#include <linux/delay.h>
#include <linux/atomic.h>
+#include <linux/blk-mq.h>
#define DM_MSG_PREFIX "table"
@@ -1695,9 +1696,13 @@ void dm_table_run_md_queue_async(struct dm_table *t)
md = dm_table_get_md(t);
queue = dm_get_md_queue(md);
if (queue) {
- spin_lock_irqsave(queue->queue_lock, flags);
- blk_run_queue_async(queue);
- spin_unlock_irqrestore(queue->queue_lock, flags);
+ if (queue->mq_ops)
+ blk_mq_run_hw_queues(queue, true);
+ else {
+ spin_lock_irqsave(queue->queue_lock, flags);
+ blk_run_queue_async(queue);
+ spin_unlock_irqrestore(queue->queue_lock, flags);
+ }
}
}
EXPORT_SYMBOL(dm_table_run_md_queue_async);