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lguest: net block unneeded receive queue update notifications 

Number of exits transmitting 10GB Guest->Host before:
	network xmit 7858610 recv 118136

After:
	network xmit 7750233 recv 1

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell 2008-07-29 09:58:35 -05:00
parent b5111790fa
commit 5dae785a82
1 changed files with 13 additions and 1 deletions
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14
Documentation/lguest/lguest.c
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@ -933,6 +933,11 @@ static bool handle_tun_input(int fd, struct device *dev)
/* FIXME: Actually want DRIVER_ACTIVE here. */
if (dev->desc->status & VIRTIO_CONFIG_S_DRIVER_OK)
warn("network: no dma buffer!");
/* Now tell it we want to know if new things appear. */
dev->vq->vring.used->flags &= ~VRING_USED_F_NO_NOTIFY;
wmb();
/* We'll turn this back on if input buffers are registered. */
return false;
} else if (out_num)
@ -969,6 +974,13 @@ static void enable_fd(int fd, struct virtqueue *vq)
write(waker_fd, &vq->dev->fd, sizeof(vq->dev->fd));
}
static void net_enable_fd(int fd, struct virtqueue *vq)
{
/* We don't need to know again when Guest refills receive buffer. */
vq->vring.used->flags |= VRING_USED_F_NO_NOTIFY;
enable_fd(fd, vq);
}
/* When the Guest tells us they updated the status field, we handle it. */
static void update_device_status(struct device *dev)
{
@ -1426,7 +1438,7 @@ static void setup_tun_net(char *arg)
/* Network devices need a receive and a send queue, just like
* console. */
add_virtqueue(dev, VIRTQUEUE_NUM, enable_fd);
add_virtqueue(dev, VIRTQUEUE_NUM, net_enable_fd);
add_virtqueue(dev, VIRTQUEUE_NUM, handle_net_output);
/* We need a socket to perform the magic network ioctls to bring up the