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vhost: introduce vhost_exceeds_weight()

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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>
This commit is contained in:
Jason Wang 2019-05-17 00:29:49 -04:00 committed by Michael S. Tsirkin
parent 6166e5330c
commit e82b9b0727
5 changed files with 48 additions and 20 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

22
drivers/vhost/net.c
View file

@ -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 @@ static void handle_tx_copy(struct vhost_net *net, struct socket *sock)
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);

9
drivers/vhost/scsi.c
View file

@ -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);

20
drivers/vhost/vhost.c
View file

@ -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);

5
drivers/vhost/vhost.h
View file

@ -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 *);

12
drivers/vhost/vsock.c
View file

@ -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);