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authorRichard W.M. Jones <rjones@redhat.com>2017-08-10 19:56:52 +0300
committerMartin K. Petersen <martin.petersen@oracle.com>2017-08-25 05:28:51 +0300
commit582b0ab200105b06704cef6da814fbde4c2ca00b (patch)
tree56ac16fe5cfd4459b34b7f7a49a8639c59e1ed7a /drivers/scsi/virtio_scsi.c
parent44ed8089e991a60d614abe0ee4b9057a28b364e4 (diff)
downloadlinux-582b0ab200105b06704cef6da814fbde4c2ca00b.tar.xz
scsi: virtio: virtio_scsi: Set can_queue to the length of the virtqueue.
Since switching to blk-mq as the default in commit 5c279bd9e406 ("scsi: default to scsi-mq"), virtio-scsi LUNs consume about 10x as much kernel memory. qemu currently allocates a fixed 128 entry virtqueue. can_queue currently is set to 1024. But with indirect descriptors, each command in the queue takes 1 virtqueue entry, so the number of commands which can be queued is equal to the length of the virtqueue. Note I intend to send a patch to qemu to allow the virtqueue size to be configured from the qemu command line. Signed-off-by: Richard W.M. Jones <rjones@redhat.com> Acked-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Diffstat (limited to 'drivers/scsi/virtio_scsi.c')
-rw-r--r--drivers/scsi/virtio_scsi.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c
index 9be211d68b15..7c28e8d4955a 100644
--- a/drivers/scsi/virtio_scsi.c
+++ b/drivers/scsi/virtio_scsi.c
@@ -818,7 +818,6 @@ static struct scsi_host_template virtscsi_host_template_single = {
.eh_timed_out = virtscsi_eh_timed_out,
.slave_alloc = virtscsi_device_alloc,
- .can_queue = 1024,
.dma_boundary = UINT_MAX,
.use_clustering = ENABLE_CLUSTERING,
.target_alloc = virtscsi_target_alloc,
@@ -839,7 +838,6 @@ static struct scsi_host_template virtscsi_host_template_multi = {
.eh_timed_out = virtscsi_eh_timed_out,
.slave_alloc = virtscsi_device_alloc,
- .can_queue = 1024,
.dma_boundary = UINT_MAX,
.use_clustering = ENABLE_CLUSTERING,
.target_alloc = virtscsi_target_alloc,
@@ -972,6 +970,8 @@ static int virtscsi_probe(struct virtio_device *vdev)
if (err)
goto virtscsi_init_failed;
+ shost->can_queue = virtqueue_get_vring_size(vscsi->req_vqs[0].vq);
+
cmd_per_lun = virtscsi_config_get(vdev, cmd_per_lun) ?: 1;
shost->cmd_per_lun = min_t(u32, cmd_per_lun, shost->can_queue);
shost->max_sectors = virtscsi_config_get(vdev, max_sectors) ?: 0xFFFF;