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| author |   Richard W.M. Jones <rjones@redhat.com> | 2017-08-10 17:56:52 +0100 |
|---|---|---|
| committer |   Martin K. Petersen <martin.petersen@oracle.com> | 2017-08-24 22:28:51 -0400 |
| commit | 582b0ab200105b06704cef6da814fbde4c2ca00b (patch) | |
| tree | 56ac16fe5cfd4459b34b7f7a49a8639c59e1ed7a /drivers/scsi/virtio_scsi.c | |
| parent | scsi: virtio: Reduce BUG if total_sg > virtqueue size to WARN. (diff) | |
| download | linux-dev-582b0ab200105b06704cef6da814fbde4c2ca00b.tar.xz linux-dev-582b0ab200105b06704cef6da814fbde4c2ca00b.zip | |
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.c | 4 |
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; |