vhost: introduce vhost_exceeds_weight()
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>
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@ -604,12 +604,6 @@ static size_t init_iov_iter(struct vhost_virtqueue *vq, struct iov_iter *iter,
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return iov_iter_count(iter);
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}
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static bool vhost_exceeds_weight(int pkts, int total_len)
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{
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return total_len >= VHOST_NET_WEIGHT ||
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pkts >= VHOST_NET_PKT_WEIGHT;
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}
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static int get_tx_bufs(struct vhost_net *net,
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struct vhost_net_virtqueue *nvq,
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struct msghdr *msg,
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@ -845,10 +839,8 @@ done:
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vq->heads[nvq->done_idx].id = cpu_to_vhost32(vq, head);
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vq->heads[nvq->done_idx].len = 0;
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++nvq->done_idx;
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if (vhost_exceeds_weight(++sent_pkts, total_len)) {
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vhost_poll_queue(&vq->poll);
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if (vhost_exceeds_weight(vq, ++sent_pkts, total_len))
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break;
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}
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}
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vhost_tx_batch(net, nvq, sock, &msg);
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@ -951,10 +943,9 @@ static void handle_tx_zerocopy(struct vhost_net *net, struct socket *sock)
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else
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vhost_zerocopy_signal_used(net, vq);
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vhost_net_tx_packet(net);
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if (unlikely(vhost_exceeds_weight(++sent_pkts, total_len))) {
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vhost_poll_queue(&vq->poll);
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if (unlikely(vhost_exceeds_weight(vq, ++sent_pkts,
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total_len)))
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break;
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}
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}
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}
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@ -1239,10 +1230,8 @@ static void handle_rx(struct vhost_net *net)
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vhost_log_write(vq, vq_log, log, vhost_len,
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vq->iov, in);
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total_len += vhost_len;
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if (unlikely(vhost_exceeds_weight(++recv_pkts, total_len))) {
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vhost_poll_queue(&vq->poll);
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if (unlikely(vhost_exceeds_weight(vq, ++recv_pkts, total_len)))
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goto out;
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}
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}
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if (unlikely(busyloop_intr))
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vhost_poll_queue(&vq->poll);
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@ -1338,7 +1327,8 @@ static int vhost_net_open(struct inode *inode, struct file *f)
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vhost_net_buf_init(&n->vqs[i].rxq);
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}
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vhost_dev_init(dev, vqs, VHOST_NET_VQ_MAX,
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UIO_MAXIOV + VHOST_NET_BATCH);
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UIO_MAXIOV + VHOST_NET_BATCH,
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VHOST_NET_WEIGHT, VHOST_NET_PKT_WEIGHT);
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vhost_poll_init(n->poll + VHOST_NET_VQ_TX, handle_tx_net, EPOLLOUT, dev);
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vhost_poll_init(n->poll + VHOST_NET_VQ_RX, handle_rx_net, EPOLLIN, dev);
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@ -57,6 +57,12 @@
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#define VHOST_SCSI_PREALLOC_UPAGES 2048
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#define VHOST_SCSI_PREALLOC_PROT_SGLS 2048
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/* Max number of requests before requeueing the job.
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* Using this limit prevents one virtqueue from starving others with
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* request.
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*/
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#define VHOST_SCSI_WEIGHT 256
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struct vhost_scsi_inflight {
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/* Wait for the flush operation to finish */
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struct completion comp;
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@ -1621,7 +1627,8 @@ static int vhost_scsi_open(struct inode *inode, struct file *f)
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vqs[i] = &vs->vqs[i].vq;
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vs->vqs[i].vq.handle_kick = vhost_scsi_handle_kick;
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}
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vhost_dev_init(&vs->dev, vqs, VHOST_SCSI_MAX_VQ, UIO_MAXIOV);
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vhost_dev_init(&vs->dev, vqs, VHOST_SCSI_MAX_VQ, UIO_MAXIOV,
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VHOST_SCSI_WEIGHT, 0);
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vhost_scsi_init_inflight(vs, NULL);
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@ -413,8 +413,24 @@ static void vhost_dev_free_iovecs(struct vhost_dev *dev)
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vhost_vq_free_iovecs(dev->vqs[i]);
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}
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bool vhost_exceeds_weight(struct vhost_virtqueue *vq,
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int pkts, int total_len)
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{
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struct vhost_dev *dev = vq->dev;
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if ((dev->byte_weight && total_len >= dev->byte_weight) ||
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pkts >= dev->weight) {
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vhost_poll_queue(&vq->poll);
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return true;
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}
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return false;
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}
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EXPORT_SYMBOL_GPL(vhost_exceeds_weight);
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void vhost_dev_init(struct vhost_dev *dev,
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struct vhost_virtqueue **vqs, int nvqs, int iov_limit)
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struct vhost_virtqueue **vqs, int nvqs,
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int iov_limit, int weight, int byte_weight)
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{
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struct vhost_virtqueue *vq;
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int i;
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@ -428,6 +444,8 @@ void vhost_dev_init(struct vhost_dev *dev,
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dev->mm = NULL;
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dev->worker = NULL;
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dev->iov_limit = iov_limit;
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dev->weight = weight;
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dev->byte_weight = byte_weight;
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init_llist_head(&dev->work_list);
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init_waitqueue_head(&dev->wait);
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INIT_LIST_HEAD(&dev->read_list);
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@ -171,10 +171,13 @@ struct vhost_dev {
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struct list_head pending_list;
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wait_queue_head_t wait;
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int iov_limit;
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int weight;
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int byte_weight;
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};
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bool vhost_exceeds_weight(struct vhost_virtqueue *vq, int pkts, int total_len);
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void vhost_dev_init(struct vhost_dev *, struct vhost_virtqueue **vqs,
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int nvqs, int iov_limit);
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int nvqs, int iov_limit, int weight, int byte_weight);
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long vhost_dev_set_owner(struct vhost_dev *dev);
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bool vhost_dev_has_owner(struct vhost_dev *dev);
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long vhost_dev_check_owner(struct vhost_dev *);
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@ -21,6 +21,14 @@
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#include "vhost.h"
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#define VHOST_VSOCK_DEFAULT_HOST_CID 2
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/* Max number of bytes transferred before requeueing the job.
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* Using this limit prevents one virtqueue from starving others. */
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#define VHOST_VSOCK_WEIGHT 0x80000
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/* Max number of packets transferred before requeueing the job.
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* Using this limit prevents one virtqueue from starving others with
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* small pkts.
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*/
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#define VHOST_VSOCK_PKT_WEIGHT 256
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enum {
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VHOST_VSOCK_FEATURES = VHOST_FEATURES,
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@ -531,7 +539,9 @@ static int vhost_vsock_dev_open(struct inode *inode, struct file *file)
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vsock->vqs[VSOCK_VQ_TX].handle_kick = vhost_vsock_handle_tx_kick;
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vsock->vqs[VSOCK_VQ_RX].handle_kick = vhost_vsock_handle_rx_kick;
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vhost_dev_init(&vsock->dev, vqs, ARRAY_SIZE(vsock->vqs), UIO_MAXIOV);
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vhost_dev_init(&vsock->dev, vqs, ARRAY_SIZE(vsock->vqs),
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UIO_MAXIOV, VHOST_VSOCK_PKT_WEIGHT,
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VHOST_VSOCK_WEIGHT);
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file->private_data = vsock;
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spin_lock_init(&vsock->send_pkt_list_lock);
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