LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Jason Wang <jasowang@redhat.com>
To: mst@redhat.com, jasowang@redhat.com,
	virtualization@lists.linux-foundation.org, kvm@vger.kernel.org,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: pbonzini@redhat.com, stefanha@redhat.com
Subject: [PATCH V2 1/4] vhost: introduce vhost_exceeds_weight()
Date: Fri, 17 May 2019 00:29:49 -0400	[thread overview]
Message-ID: <1558067392-11740-2-git-send-email-jasowang@redhat.com> (raw)
In-Reply-To: <1558067392-11740-1-git-send-email-jasowang@redhat.com>

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>
---
 drivers/vhost/net.c   | 22 ++++++----------------
 drivers/vhost/scsi.c  |  9 ++++++++-
 drivers/vhost/vhost.c | 20 +++++++++++++++++++-
 drivers/vhost/vhost.h |  5 ++++-
 drivers/vhost/vsock.c | 12 +++++++++++-
 5 files changed, 48 insertions(+), 20 deletions(-)

diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index df51a35..061a06d 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -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,
@@ -845,10 +839,8 @@ 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);
@@ -951,10 +943,9 @@ 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;
-		}
 	}
 }
 
@@ -1239,10 +1230,8 @@ 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);
@@ -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);
diff --git a/drivers/vhost/scsi.c b/drivers/vhost/scsi.c
index 618fb64..d830579 100644
--- a/drivers/vhost/scsi.c
+++ b/drivers/vhost/scsi.c
@@ -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;
@@ -1622,7 +1628,8 @@ 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);
 
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 351af88..290d6e5 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -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);
diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
index 9490e7d..27a78a9 100644
--- a/drivers/vhost/vhost.h
+++ b/drivers/vhost/vhost.h
@@ -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 *);
diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
index bb5fc0e..47c6d4d 100644
--- a/drivers/vhost/vsock.c
+++ b/drivers/vhost/vsock.c
@@ -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);
-- 
1.8.3.1


  reply	other threads:[~2019-05-17  4:30 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-17  4:29 [PATCH V2 0/4] Prevent vhost kthread from hogging CPU Jason Wang
2019-05-17  4:29 ` Jason Wang [this message]
2019-05-17  4:29 ` [PATCH V2 2/4] vhost_net: fix possible infinite loop Jason Wang
2019-05-17  4:29 ` [PATCH V2 3/4] vhost: vsock: add weight support Jason Wang
2019-05-17  4:29 ` [PATCH V2 4/4] vhost: scsi: " Jason Wang
2019-05-17  9:10 ` [PATCH V2 0/4] Prevent vhost kthread from hogging CPU Stefan Hajnoczi
2019-05-18 20:27 ` David Miller
2019-05-23 17:22   ` Michael S. Tsirkin
2019-05-20 12:52 ` Michael S. Tsirkin
2019-05-23  2:37   ` Jason Wang

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=1558067392-11740-2-git-send-email-jasowang@redhat.com \
    --to=jasowang@redhat.com \
    --cc=kvm@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mst@redhat.com \
    --cc=netdev@vger.kernel.org \
    --cc=pbonzini@redhat.com \
    --cc=stefanha@redhat.com \
    --cc=virtualization@lists.linux-foundation.org \
    --subject='Re: [PATCH V2 1/4] vhost: introduce vhost_exceeds_weight()' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).