vhost: introduce vhost_exceeds_weight()
commit e82b9b0727ff6d665fff2d326162b460dded554d upstream.
We used to have vhost_exceeds_weight() for vhost-net to:
- prevent vhost kthread from hogging the cpu
- balance the time spent between TX and RX
This function could be useful for vsock and scsi as well. So move it
to vhost.c. Device must specify a weight which counts the number of
requests, or it can also specific a byte_weight which counts the
number of bytes that has been processed.
Signed-off-by: Jason Wang <jasowang@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
[bwh: Backported to 4.9:
- In vhost_net, both Tx modes are handled in one loop in handle_tx()
- Adjust context]
Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index 0132cbd..9c50354 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -357,12 +357,6 @@
return r;
}
-static bool vhost_exceeds_weight(int pkts, int total_len)
-{
- return total_len >= VHOST_NET_WEIGHT ||
- pkts >= VHOST_NET_PKT_WEIGHT;
-}
-
/* Expects to be always run from workqueue - which acts as
* read-size critical section for our kind of RCU. */
static void handle_tx(struct vhost_net *net)
@@ -487,10 +481,9 @@
vhost_zerocopy_signal_used(net, vq);
total_len += len;
vhost_net_tx_packet(net);
- if (unlikely(vhost_exceeds_weight(++sent_pkts, total_len))) {
- vhost_poll_queue(&vq->poll);
+ if (unlikely(vhost_exceeds_weight(vq, ++sent_pkts,
+ total_len)))
break;
- }
}
out:
mutex_unlock(&vq->mutex);
@@ -768,10 +761,8 @@
vhost_log_write(vq, vq_log, log, vhost_len,
vq->iov, in);
total_len += vhost_len;
- if (unlikely(vhost_exceeds_weight(++recv_pkts, total_len))) {
- vhost_poll_queue(&vq->poll);
+ if (unlikely(vhost_exceeds_weight(vq, ++recv_pkts, total_len)))
goto out;
- }
}
vhost_net_enable_vq(net, vq);
out:
@@ -842,7 +833,8 @@
n->vqs[i].vhost_hlen = 0;
n->vqs[i].sock_hlen = 0;
}
- vhost_dev_init(dev, vqs, VHOST_NET_VQ_MAX);
+ vhost_dev_init(dev, vqs, VHOST_NET_VQ_MAX,
+ VHOST_NET_WEIGHT, VHOST_NET_PKT_WEIGHT);
vhost_poll_init(n->poll + VHOST_NET_VQ_TX, handle_tx_net, POLLOUT, dev);
vhost_poll_init(n->poll + VHOST_NET_VQ_RX, handle_rx_net, POLLIN, dev);