This has vhost-scsi support the worker ioctls by calling the
vhost_worker_ioctl helper.
With a single worker, the single thread becomes a bottlneck when trying
to use 3 or more virtqueues like:
fio --filename=/dev/sdb --direct=1 --rw=randrw --bs=4k \
--ioengine=libaio --iodepth=128 --numjobs=3
With the patches and doing a worker per vq, we can scale to at least
16 vCPUs/vqs (that's my system limit) with the same command fio command
above with numjobs=16:
fio --filename=/dev/sdb --direct=1 --rw=randrw --bs=4k \
--ioengine=libaio --iodepth=64 --numjobs=16
which gives around 2002K IOPs.
Note that for testing I dropped depth to 64 above because the vhost/virt
layer supports only 1024 total commands per device. And the only tuning I
did was set LIO's emulate_pr to 0 to avoid LIO's PR lock in the main IO
path which becomes an issue at around 12 jobs/virtqueues.
Signed-off-by: Mike Christie <michael.chris...@oracle.com>
---
drivers/vhost/scsi.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/drivers/vhost/scsi.c b/drivers/vhost/scsi.c
index 2c3cf487cc71..c83f7f043470 100644
--- a/drivers/vhost/scsi.c
+++ b/drivers/vhost/scsi.c
@@ -1927,6 +1927,14 @@ vhost_scsi_ioctl(struct file *f,
if (copy_from_user(&features, featurep, sizeof features))
return -EFAULT;
return vhost_scsi_set_features(vs, features);
+ case VHOST_NEW_WORKER:
+ case VHOST_FREE_WORKER:
+ case VHOST_ATTACH_VRING_WORKER:
+ case VHOST_GET_VRING_WORKER:
+ mutex_lock(&vs->dev.mutex);
+ r = vhost_worker_ioctl(&vs->dev, ioctl, argp);
+ mutex_unlock(&vs->dev.mutex);
+ return r;
default:
mutex_lock(&vs->dev.mutex);
r = vhost_dev_ioctl(&vs->dev, ioctl, argp);
--
2.25.1
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