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authorRusty Russell <rusty@rustcorp.com.au>2012-01-12 15:44:42 +1030
committerRusty Russell <rusty@rustcorp.com.au>2012-01-12 15:44:42 +1030
commit7b21e34fd1c272e3a8c3846168f2f6287a4cd72b (patch)
tree0f94c9f834f5b7cd8ba87168df892ed17b09cb8f /drivers/virtio/virtio_pci.c
parente343a895a9f342f239c5e3c5ffc6c0b1707e6244 (diff)
virtio: harsher barriers for rpmsg.
We were cheating with our barriers; using the smp ones rather than the real device ones. That was fine, until rpmsg came along, which is used to talk to a real device (a non-SMP CPU). Unfortunately, just putting back the real barriers (reverting d57ed95d) causes a performance regression on virtio-pci. In particular, Amos reports netbench's TCP_RR over virtio_net CPU utilization increased up to 35% while throughput went down by up to 14%. By comparison, this branch is in the noise. Reference: https://lkml.org/lkml/2011/12/11/22 Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Diffstat (limited to 'drivers/virtio/virtio_pci.c')
-rw-r--r--drivers/virtio/virtio_pci.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/virtio/virtio_pci.c b/drivers/virtio/virtio_pci.c
index baabb7937ec..688b42d28da 100644
--- a/drivers/virtio/virtio_pci.c
+++ b/drivers/virtio/virtio_pci.c
@@ -414,8 +414,8 @@ static struct virtqueue *setup_vq(struct virtio_device *vdev, unsigned index,
vp_dev->ioaddr + VIRTIO_PCI_QUEUE_PFN);
/* create the vring */
- vq = vring_new_virtqueue(info->num, VIRTIO_PCI_VRING_ALIGN,
- vdev, info->queue, vp_notify, callback, name);
+ vq = vring_new_virtqueue(info->num, VIRTIO_PCI_VRING_ALIGN, vdev,
+ true, info->queue, vp_notify, callback, name);
if (!vq) {
err = -ENOMEM;
goto out_activate_queue;