3.16.72-rc1 review patch. If anyone has any objections, please let me know.
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From: Jason Wang jasowang@redhat.com
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 3.16: - Drop changes to vhost_vsock - In vhost_net, both Tx modes are handled in one loop in handle_tx() - Adjust context] Signed-off-by: Ben Hutchings ben@decadent.org.uk --- --- a/drivers/vhost/net.c +++ b/drivers/vhost/net.c @@ -335,12 +335,6 @@ static void vhost_zerocopy_callback(stru rcu_read_unlock_bh(); }
-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) @@ -463,10 +457,8 @@ static void handle_tx(struct vhost_net * 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 (vhost_exceeds_weight(vq, ++sent_pkts, total_len)) break; - } } out: mutex_unlock(&vq->mutex); @@ -673,10 +665,8 @@ static void handle_rx(struct vhost_net * if (unlikely(vq_log)) vhost_log_write(vq, vq_log, log, vhost_len); 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))) break; - } } out: mutex_unlock(&vq->mutex); @@ -746,7 +736,8 @@ static int vhost_net_open(struct inode * 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); --- a/drivers/vhost/scsi.c +++ b/drivers/vhost/scsi.c @@ -60,6 +60,12 @@ #define TCM_VHOST_PREALLOC_UPAGES 2048 #define TCM_VHOST_PREALLOC_PROT_SGLS 512
+/* 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; @@ -1576,7 +1582,8 @@ static int vhost_scsi_open(struct inode 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); + vhost_dev_init(&vs->dev, vqs, VHOST_SCSI_MAX_VQ, + VHOST_SCSI_WEIGHT, 0);
tcm_vhost_init_inflight(vs, NULL);
--- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -292,8 +292,24 @@ static void vhost_dev_free_iovecs(struct 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) + struct vhost_virtqueue **vqs, int nvqs, + int weight, int byte_weight) { struct vhost_virtqueue *vq; int i; @@ -308,6 +324,8 @@ void vhost_dev_init(struct vhost_dev *de spin_lock_init(&dev->work_lock); INIT_LIST_HEAD(&dev->work_list); dev->worker = NULL; + dev->weight = weight; + dev->byte_weight = byte_weight;
for (i = 0; i < dev->nvqs; ++i) { vq = dev->vqs[i]; --- a/drivers/vhost/vhost.h +++ b/drivers/vhost/vhost.h @@ -123,9 +123,13 @@ struct vhost_dev { spinlock_t work_lock; struct list_head work_list; struct task_struct *worker; + int weight; + int byte_weight; };
-void vhost_dev_init(struct vhost_dev *, struct vhost_virtqueue **vqs, int nvqs); +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 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 *);