Commit e82b9b07 authored by Jason Wang's avatar Jason Wang Committed by Michael S. Tsirkin
Browse files

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: default avatarJason Wang <jasowang@redhat.com>
Reviewed-by: default avatarStefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
parent 6166e533

drivers/vhost/net.c

+6 −16
Original line number Diff line number Diff line
@@ -604,12 +604,6 @@ static size_t init_iov_iter(struct vhost_virtqueue *vq, struct iov_iter *iter, 
	return iov_iter_count(iter);

}



static bool vhost_exceeds_weight(int pkts, int total_len)

{

	return total_len >= VHOST_NET_WEIGHT ||

	       pkts >= VHOST_NET_PKT_WEIGHT;

}



static int get_tx_bufs(struct vhost_net *net,

		       struct vhost_net_virtqueue *nvq,

		       struct msghdr *msg,
@@ -845,11 +839,9 @@ done: 
		vq->heads[nvq->done_idx].id = cpu_to_vhost32(vq, head);

		vq->heads[nvq->done_idx].len = 0;

		++nvq->done_idx;

		if (vhost_exceeds_weight(++sent_pkts, total_len)) {

			vhost_poll_queue(&vq->poll);

		if (vhost_exceeds_weight(vq, ++sent_pkts, total_len))

			break;

	}

	}



	vhost_tx_batch(net, nvq, sock, &msg);

}
@@ -951,12 +943,11 @@ static void handle_tx_zerocopy(struct vhost_net *net, struct socket *sock) 
		else

			vhost_zerocopy_signal_used(net, vq);

		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;

	}

}

}



/* Expects to be always run from workqueue - which acts as

 * read-size critical section for our kind of RCU. */
@@ -1239,11 +1230,9 @@ static void handle_rx(struct vhost_net *net) 
			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;

	}

	}

	if (unlikely(busyloop_intr))

		vhost_poll_queue(&vq->poll);

	else
@@ -1338,7 +1327,8 @@ static int vhost_net_open(struct inode *inode, struct file *f) 
		vhost_net_buf_init(&n->vqs[i].rxq);

	}

	vhost_dev_init(dev, vqs, VHOST_NET_VQ_MAX,

		       UIO_MAXIOV + VHOST_NET_BATCH);

		       UIO_MAXIOV + VHOST_NET_BATCH,

		       VHOST_NET_WEIGHT, VHOST_NET_PKT_WEIGHT);



	vhost_poll_init(n->poll + VHOST_NET_VQ_TX, handle_tx_net, EPOLLOUT, dev);

	vhost_poll_init(n->poll + VHOST_NET_VQ_RX, handle_rx_net, EPOLLIN, dev);

drivers/vhost/scsi.c

+8 −1
Original line number Diff line number Diff line
@@ -57,6 +57,12 @@ 
#define VHOST_SCSI_PREALLOC_UPAGES 2048

#define VHOST_SCSI_PREALLOC_PROT_SGLS 2048



/* Max number of requests before requeueing the job.

 * Using this limit prevents one virtqueue from starving others with

 * request.

 */

#define VHOST_SCSI_WEIGHT 256



struct vhost_scsi_inflight {

	/* Wait for the flush operation to finish */

	struct completion comp;
@@ -1621,7 +1627,8 @@ static int vhost_scsi_open(struct inode *inode, struct file *f) 
		vqs[i] = &vs->vqs[i].vq;

		vs->vqs[i].vq.handle_kick = vhost_scsi_handle_kick;

	}

	vhost_dev_init(&vs->dev, vqs, VHOST_SCSI_MAX_VQ, UIO_MAXIOV);

	vhost_dev_init(&vs->dev, vqs, VHOST_SCSI_MAX_VQ, UIO_MAXIOV,

		       VHOST_SCSI_WEIGHT, 0);



	vhost_scsi_init_inflight(vs, NULL);

drivers/vhost/vhost.c

+19 −1
Original line number Diff line number Diff line
@@ -413,8 +413,24 @@ static void vhost_dev_free_iovecs(struct vhost_dev *dev) 
		vhost_vq_free_iovecs(dev->vqs[i]);

}



bool vhost_exceeds_weight(struct vhost_virtqueue *vq,

			  int pkts, int total_len)

{

	struct vhost_dev *dev = vq->dev;



	if ((dev->byte_weight && total_len >= dev->byte_weight) ||

	    pkts >= dev->weight) {

		vhost_poll_queue(&vq->poll);

		return true;

	}



	return false;

}

EXPORT_SYMBOL_GPL(vhost_exceeds_weight);



void vhost_dev_init(struct vhost_dev *dev,

		    struct vhost_virtqueue **vqs, int nvqs, int iov_limit)

		    struct vhost_virtqueue **vqs, int nvqs,

		    int iov_limit, int weight, int byte_weight)

{

	struct vhost_virtqueue *vq;

	int i;
@@ -428,6 +444,8 @@ void vhost_dev_init(struct vhost_dev *dev, 
	dev->mm = NULL;

	dev->worker = NULL;

	dev->iov_limit = iov_limit;

	dev->weight = weight;

	dev->byte_weight = byte_weight;

	init_llist_head(&dev->work_list);

	init_waitqueue_head(&dev->wait);

	INIT_LIST_HEAD(&dev->read_list);

drivers/vhost/vhost.h

+4 −1
Original line number Diff line number Diff line
@@ -171,10 +171,13 @@ struct vhost_dev { 
	struct list_head pending_list;

	wait_queue_head_t wait;

	int iov_limit;

	int weight;

	int byte_weight;

};



bool vhost_exceeds_weight(struct vhost_virtqueue *vq, int pkts, int total_len);

void vhost_dev_init(struct vhost_dev *, struct vhost_virtqueue **vqs,

		    int nvqs, int iov_limit);

		    int nvqs, int iov_limit, int weight, int byte_weight);

long vhost_dev_set_owner(struct vhost_dev *dev);

bool vhost_dev_has_owner(struct vhost_dev *dev);

long vhost_dev_check_owner(struct vhost_dev *);

drivers/vhost/vsock.c

+11 −1
Original line number Diff line number Diff line
@@ -21,6 +21,14 @@ 
#include "vhost.h"



#define VHOST_VSOCK_DEFAULT_HOST_CID	2

/* Max number of bytes transferred before requeueing the job.

 * Using this limit prevents one virtqueue from starving others. */

#define VHOST_VSOCK_WEIGHT 0x80000

/* Max number of packets transferred before requeueing the job.

 * Using this limit prevents one virtqueue from starving others with

 * small pkts.

 */

#define VHOST_VSOCK_PKT_WEIGHT 256



enum {

	VHOST_VSOCK_FEATURES = VHOST_FEATURES,
@@ -531,7 +539,9 @@ static int vhost_vsock_dev_open(struct inode *inode, struct file *file) 
	vsock->vqs[VSOCK_VQ_TX].handle_kick = vhost_vsock_handle_tx_kick;

	vsock->vqs[VSOCK_VQ_RX].handle_kick = vhost_vsock_handle_rx_kick;



	vhost_dev_init(&vsock->dev, vqs, ARRAY_SIZE(vsock->vqs), UIO_MAXIOV);

	vhost_dev_init(&vsock->dev, vqs, ARRAY_SIZE(vsock->vqs),

		       UIO_MAXIOV, VHOST_VSOCK_PKT_WEIGHT,

		       VHOST_VSOCK_WEIGHT);



	file->private_data = vsock;

	spin_lock_init(&vsock->send_pkt_list_lock);

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