Most virtio setups have a fairly limited number of ring entries available.
Enable S/G entry merging by default to fit into less of them. This restores
the behavior at time of the virtio-blk blk-mq conversion, which was changed
by commit "block: add queue flag for disabling SG merging" which made the
behavior optional, but didn't update the existing drivers to keep their
previous behavior.
Signed-off-by: Christoph Hellwig <h...@lst.de>
---
drivers/block/virtio_blk.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index 0a58140..311b857 100644
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -634,7 +634,7 @@ static int virtblk_probe(struct virtio_device *vdev)
vblk->tag_set.ops = &virtio_mq_ops;
vblk->tag_set.queue_depth = virtblk_queue_depth;
vblk->tag_set.numa_node = NUMA_NO_NODE;
- vblk->tag_set.flags = BLK_MQ_F_SHOULD_MERGE;
+ vblk->tag_set.flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_SG_MERGE;
vblk->tag_set.cmd_size =
sizeof(struct virtblk_req) +
sizeof(struct scatterlist) * sg_elems;
--
1.9.1
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