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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 /tools/virtio/virtio_test.c
parente343a895a9f342f239c5e3c5ffc6c0b1707e6244 (diff)
downloadlinux-7b21e34fd1c272e3a8c3846168f2f6287a4cd72b.tar.gz
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 'tools/virtio/virtio_test.c')
-rw-r--r--tools/virtio/virtio_test.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/tools/virtio/virtio_test.c b/tools/virtio/virtio_test.c
index 74d3331bdaf9..0740284396c1 100644
--- a/tools/virtio/virtio_test.c
+++ b/tools/virtio/virtio_test.c
@@ -92,7 +92,8 @@ static void vq_info_add(struct vdev_info *dev, int num)
 	assert(r >= 0);
 	memset(info->ring, 0, vring_size(num, 4096));
 	vring_init(&info->vring, num, info->ring, 4096);
-	info->vq = vring_new_virtqueue(info->vring.num, 4096, &dev->vdev, info->ring,
+	info->vq = vring_new_virtqueue(info->vring.num, 4096, &dev->vdev,
+				       true, info->ring,
 				       vq_notify, vq_callback, "test");
 	assert(info->vq);
 	info->vq->priv = info;