[PATCH 15/15] nvme-multipath: enable polled I/O

Christoph Hellwig
2021-05-12T13:25:29Z

Set the poll queue flag to enable polling, given that the multipath
node just dispatches the bios to a lower queue.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
drivers/nvme/host/multipath.c | 9 +++++++++
1 file changed, 9 insertions(+)

diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c
index 516fe977606d..e95b93655d06 100644
--- a/drivers/nvme/host/multipath.c
+++ b/drivers/nvme/host/multipath.c
@@ -446,6 +446,15 @@ int nvme_mpath_alloc_disk(struct nvme_ctrl *ctrl, struct nvme_ns_head *head)
goto out;
blk_queue_flag_set(QUEUE_FLAG_NONROT, q);
blk_queue_flag_set(QUEUE_FLAG_NOWAIT, q);
+ /*
+ * This assumes all controllers that refer to a namespace either
+ * support poll queues or not. That is not a strict guarantee,
+ * but if the assumption is wrong the effect is only suboptimal
+ * performance but not correctness problem.
+ */
+ if (ctrl->tagset->nr_maps > HCTX_TYPE_POLL &&
+ ctrl->tagset->map[HCTX_TYPE_POLL].nr_queues)
+ blk_queue_flag_set(QUEUE_FLAG_POLL, q);

/* set to a default value for 512 until disk is validated */
blk_queue_logical_block_size(q, 512);
--
2.30.2