From 7b21e34fd1c272e3a8c3846168f2f6287a4cd72b Mon Sep 17 00:00:00 2001 From: Rusty Russell Date: Thu, 12 Jan 2012 15:44:42 +1030 Subject: 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 --- drivers/s390/kvm/kvm_virtio.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/s390/kvm') diff --git a/drivers/s390/kvm/kvm_virtio.c b/drivers/s390/kvm/kvm_virtio.c index 8af868bab20b..7bc1955337ea 100644 --- a/drivers/s390/kvm/kvm_virtio.c +++ b/drivers/s390/kvm/kvm_virtio.c @@ -198,7 +198,7 @@ static struct virtqueue *kvm_find_vq(struct virtio_device *vdev, goto out; vq = vring_new_virtqueue(config->num, KVM_S390_VIRTIO_RING_ALIGN, - vdev, (void *) config->address, + vdev, true, (void *) config->address, kvm_notify, callback, name); if (!vq) { err = -ENOMEM; -- cgit 1.4.1