[PATCH 4/4] vhost-scsi: Report direction completion support

[Mike Christie <michael.christie@oracle.com>]

This has vhost-scsi report that it supports direct completions.

When using a worker task per queue or group of queues with fast
backends then enabling direct completion and submissions increases
performance 20-30% with workloads like:

fio --filename=/dev/sdb  --direct=1 --rw=randrw --bs=8K \
    --ioengine=libaio --iodepth=128  --numjobs=$jobs

As jobs matches and passes the number of vCPUs in the VM then
the benefit increases.

However, when using a single worker then queueing completions
and submissions is best as the worker is busy handling mapping data
and setting/tearing down commands.

Signed-off-by: Mike Christie <michael.christie@oracle.com>
---
 drivers/vhost/scsi.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/vhost/scsi.c b/drivers/vhost/scsi.c
index 1f00145116f4..653c08bb2520 100644
--- a/drivers/vhost/scsi.c
+++ b/drivers/vhost/scsi.c
@@ -2959,6 +2959,7 @@ static const struct target_core_fabric_ops vhost_scsi_ops = {
 	.tfc_tpg_attrib_attrs		= vhost_scsi_tpg_attrib_attrs,
 
 	.default_compl_type		= TARGET_QUEUE_COMPL,
+	.direct_compl_supp		= 1,
 	.default_submit_type		= TARGET_QUEUE_SUBMIT,
 	.direct_submit_supp		= 1,
 };
-- 
2.43.0