Re: Increased memory usage with scsi-mq

[Christoph Hellwig <hch@lst.de>]

For now can you apply this testing patch to the guest kernel?

diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c
index 9be211d68b15..0cbe2c882e1c 100644
--- a/drivers/scsi/virtio_scsi.c
+++ b/drivers/scsi/virtio_scsi.c
@@ -818,7 +818,7 @@ static struct scsi_host_template virtscsi_host_template_single = {
 	.eh_timed_out = virtscsi_eh_timed_out,
 	.slave_alloc = virtscsi_device_alloc,
 
-	.can_queue = 1024,
+	.can_queue = 64,
 	.dma_boundary = UINT_MAX,
 	.use_clustering = ENABLE_CLUSTERING,
 	.target_alloc = virtscsi_target_alloc,
@@ -839,7 +839,7 @@ static struct scsi_host_template virtscsi_host_template_multi = {
 	.eh_timed_out = virtscsi_eh_timed_out,
 	.slave_alloc = virtscsi_device_alloc,
 
-	.can_queue = 1024,
+	.can_queue = 64,
 	.dma_boundary = UINT_MAX,
 	.use_clustering = ENABLE_CLUSTERING,
 	.target_alloc = virtscsi_target_alloc,
@@ -983,7 +983,7 @@ static int virtscsi_probe(struct virtio_device *vdev)
 	shost->max_id = num_targets;
 	shost->max_channel = 0;
 	shost->max_cmd_len = VIRTIO_SCSI_CDB_SIZE;
-	shost->nr_hw_queues = num_queues;
+	shost->nr_hw_queues = 1;
 
 #ifdef CONFIG_BLK_DEV_INTEGRITY
 	if (virtio_has_feature(vdev, VIRTIO_SCSI_F_T10_PI)) {