On Tue, Oct 27, 2009 at 09:36:18AM -0700, Shirley Ma wrote:
> Hello Michael,
>
> On Tue, 2009-10-27 at 17:27 +0200, Michael S. Tsirkin wrote:
> > Possibly GFP_ATOMIC allocations in vring_add_indirect are failing?
> > Is there a chance you are tight on guest memory for some reason?
> > with vhost, virtio does currently consume a bit more memory than
> > with userspace backend.
>
> I did see memory leak on host every time after exiting guest. I don't
> know where. Do you see it?
>
> Anyway after I reboot host and restart guest with large memory
> allocation, I do see performance improves to 3xxxMb/s, and occasionally
> reaches 40xxMb/s. But "queue full" still exists, I can avoid the problem
> by increasing send queue size from qemu.
Here's another hack to try. It will break raw sockets,
but just as a test:
diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index a140dad..e830b30 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -106,22 +106,41 @@ static void handle_tx(struct vhost_net *net)
.msg_flags = MSG_DONTWAIT,
};
size_t len, total_len = 0;
- int err;
+ int err, wmem;
size_t hdr_size;
struct socket *sock = rcu_dereference(vq->private_data);
- if (!sock || !sock_writeable(sock->sk))
+ if (!sock)
+ return;
+
+ wmem = atomic_read(&sock->sk->sk_wmem_alloc);
+ if (wmem >= sock->sk->sk_sndbuf)
return;
use_mm(net->dev.mm);
mutex_lock(&vq->mutex);
- tx_poll_stop(net);
+ vhost_no_notify(vq);
+
+ if (wmem >= sock->sk->sk_sndbuf * 3 / 4) {
+ //tx_poll_start(net);
+ } else {
+ //tx_poll_stop(net);
+ }
hdr_size = vq->hdr_size;
for (;;) {
head = vhost_get_vq_desc(&net->dev, vq, vq->iov, &out, &in);
/* Nothing new? Wait for eventfd to tell us they refilled. */
- if (head == vq->num)
+ if (head == vq->num) {
+ wmem = atomic_read(&sock->sk->sk_wmem_alloc);
+ if (wmem >= sock->sk->sk_sndbuf * 3 / 4) {
+ set_bit(SOCK_ASYNC_NOSPACE, &sock->flags);
+ break;
+ }
+ if (vhost_notify(vq)) {
+ continue;
+ }
break;
+ }
if (in) {
vq_err(vq, "Unexpected descriptor format for TX: "
"out %d, int %d\n", out, in);
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 30708c6..67bfc08 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -775,7 +775,7 @@ void vhost_no_notify(struct vhost_virtqueue *vq)
int vhost_init(void)
{
- vhost_workqueue = create_workqueue("vhost");
+ vhost_workqueue = create_singlethread_workqueue("vhost");
if (!vhost_workqueue)
return -ENOMEM;
return 0;
--
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