vhost: Add polling mode

index 971a760..558aecb 100644
@@ -742,8 +742,10 @@ static int vhost_net_open(struct inode *inode, struct file *f)
 	}
 	vhost_dev_init(dev, vqs, VHOST_NET_VQ_MAX);
 
-	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);
+	vhost_poll_init(n->poll + VHOST_NET_VQ_TX, handle_tx_net, POLLOUT,
+			vqs[VHOST_NET_VQ_TX]);
+	vhost_poll_init(n->poll + VHOST_NET_VQ_RX, handle_rx_net, POLLIN,
+			vqs[VHOST_NET_VQ_RX]);
 
 	f->private_data = n;
 

index 4f4ffa4..665eeeb 100644
@@ -1528,9 +1528,9 @@ static int vhost_scsi_open(struct inode *inode, struct file *f)
 	if (!vqs)
 		goto err_vqs;
 
-	vhost_work_init(&vs->vs_completion_work, vhost_scsi_complete_cmd_work);
-	vhost_work_init(&vs->vs_event_work, tcm_vhost_evt_work);
-
+	vhost_work_init(&vs->vs_completion_work, NULL,
+						vhost_scsi_complete_cmd_work);
+	vhost_work_init(&vs->vs_event_work, NULL, tcm_vhost_evt_work);
 	vs->vs_events_nr = 0;
 	vs->vs_events_missed = false;
 

340 lines not on this page · raw message

index 3eda654..11aaaf4 100644
@@ -24,6 +24,7 @@ struct vhost_work {
 	int			  flushing;
 	unsigned		  queue_seq;
 	unsigned		  done_seq;
+	struct vhost_virtqueue    *vq;
 };
 
 /* Poll a file (eventfd or socket) */

@@ -37,11 +38,12 @@ struct vhost_poll {
 	struct vhost_dev	 *dev;
 };
 
-void vhost_work_init(struct vhost_work *work, vhost_work_fn_t fn);
+void vhost_work_init(struct vhost_work *work, struct vhost_virtqueue *vq,
+							vhost_work_fn_t fn);
 void vhost_work_queue(struct vhost_dev *dev, struct vhost_work *work);
 
 void vhost_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn,
-		     unsigned long mask, struct vhost_dev *dev);
+		     unsigned long mask, struct vhost_virtqueue  *vq);
 int vhost_poll_start(struct vhost_poll *poll, struct file *file);
 void vhost_poll_stop(struct vhost_poll *poll);
 void vhost_poll_flush(struct vhost_poll *poll);

@@ -54,8 +56,6 @@ struct vhost_log {
 	u64 len;
 };
 
-struct vhost_virtqueue;
-
 /* The virtqueue structure describes a queue attached to a device. */
 struct vhost_virtqueue {
 	struct vhost_dev *dev;

@@ -110,6 +110,35 @@ struct vhost_virtqueue {
 	/* Log write descriptors */
 	void __user *log_base;
 	struct vhost_log *log;
+	struct {
+      /* When a virtqueue is in vqpoll.enabled mode, it declares
+       * that instead of using guest notifications (kicks) to
+       * discover new work, we prefer to continuously poll this
+       * virtqueue in the worker thread.
+       * If !enabled, the rest of the fields below are undefined.
+       */
+		bool enabled;
+      /* vqpoll.enabled doesn't always mean that this virtqueue is
+       * actually being polled: The backend (e.g., net.c) may
+       * temporarily disable it using vhost_disable/enable_notify().
+       * vqpoll.link is used to maintain the thread's round-robin
+       * list of virtqueues that actually need to be polled.
+       * Note list_empty(link) means this virtqueue isn't polled.
+       */
+		struct list_head link;
+      /* If this flag is true, the virtqueue is being shut down,
+       * so vqpoll should not be re-enabled.
+       */
+		bool shutdown;
+      /* Various counters used to decide when to enter polling mode
+       * or leave it and return to notification mode.
+       */
+		unsigned long jiffies_last_kick;
+		unsigned long jiffies_last_work;
+		int work_this_jiffy;
+		struct page *avail_page;
+		volatile struct vring_avail *avail_mapped;
+	} vqpoll;
 };
 
 struct vhost_dev {

@@ -123,6 +152,7 @@ struct vhost_dev {
 	spinlock_t work_lock;
 	struct list_head work_list;
 	struct task_struct *worker;
+	struct list_head vqpoll_list;
 };
 
 void vhost_dev_init(struct vhost_dev *, struct vhost_virtqueue **vqs, int nvqs);