[PATCH RFC v4 net-next 4/5] virtio-net: add basic interrupt coalescing support

[Jason Wang]

This patch enables the interrupt coalescing setting through ethtool.

Cc: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
Cc: Michael S. Tsirkin <mst@xxxxxxxxxx>
Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
---
 drivers/net/virtio_net.c        | 67 +++++++++++++++++++++++++++++++++++++++++
 include/uapi/linux/virtio_net.h | 12 ++++++++
 2 files changed, 79 insertions(+)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 9f420c9..2a3551a 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -142,6 +142,11 @@ struct virtnet_info {
 
 	/* Budget for polling tx completion */
 	u32 tx_work_limit;
+
+	__u32 rx_coalesce_usecs;
+	__u32 rx_max_coalesced_frames;
+	__u32 tx_coalesce_usecs;
+	__u32 tx_max_coalesced_frames;
 };
 
 struct skb_vnet_hdr {
@@ -1419,12 +1424,73 @@ static void virtnet_get_channels(struct net_device *dev,
 	channels->other_count = 0;
 }
 
+static int virtnet_set_coalesce(struct net_device *dev,
+				struct ethtool_coalesce *ec)
+{
+	struct virtnet_info *vi = netdev_priv(dev);
+	struct scatterlist sg;
+	struct virtio_net_ctrl_coalesce c;
+
+	if (!vi->has_cvq ||
+	    !virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_COALESCE))
+		return -EOPNOTSUPP;
+	if (vi->rx_coalesce_usecs != ec->rx_coalesce_usecs ||
+	    vi->rx_max_coalesced_frames != ec->rx_max_coalesced_frames) {
+		c.coalesce_usecs = ec->rx_coalesce_usecs;
+		c.max_coalesced_frames = ec->rx_max_coalesced_frames;
+		sg_init_one(&sg, &c, sizeof(c));
+		if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_COALESCE,
+					  VIRTIO_NET_CTRL_COALESCE_RX_SET,
+					  &sg)) {
+			dev_warn(&dev->dev, "Fail to set rx coalescing\n");
+			return -EINVAL;
+		}
+		vi->rx_coalesce_usecs = ec->rx_coalesce_usecs;
+		vi->rx_max_coalesced_frames = ec->rx_max_coalesced_frames;
+	}
+
+	if (vi->tx_coalesce_usecs != ec->tx_coalesce_usecs ||
+	    vi->tx_max_coalesced_frames != ec->tx_max_coalesced_frames) {
+		c.coalesce_usecs = ec->tx_coalesce_usecs;
+		c.max_coalesced_frames = ec->tx_max_coalesced_frames;
+		sg_init_one(&sg, &c, sizeof(c));
+		if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_COALESCE,
+					  VIRTIO_NET_CTRL_COALESCE_TX_SET,
+					  &sg)) {
+			dev_warn(&dev->dev, "Fail to set tx coalescing\n");
+			return -EINVAL;
+		}
+		vi->tx_coalesce_usecs = ec->tx_coalesce_usecs;
+		vi->tx_max_coalesced_frames = ec->tx_max_coalesced_frames;
+	}
+
+	vi->tx_work_limit = ec->tx_max_coalesced_frames_irq;
+
+	return 0;
+}
+
+static int virtnet_get_coalesce(struct net_device *dev,
+				struct ethtool_coalesce *ec)
+{
+	struct virtnet_info *vi = netdev_priv(dev);
+
+	ec->rx_coalesce_usecs = vi->rx_coalesce_usecs;
+	ec->rx_max_coalesced_frames = vi->rx_max_coalesced_frames;
+	ec->tx_coalesce_usecs = vi->tx_coalesce_usecs;
+	ec->tx_max_coalesced_frames = vi->tx_max_coalesced_frames;
+	ec->tx_max_coalesced_frames_irq = vi->tx_work_limit;
+
+	return 0;
+}
+
 static const struct ethtool_ops virtnet_ethtool_ops = {
 	.get_drvinfo = virtnet_get_drvinfo,
 	.get_link = ethtool_op_get_link,
 	.get_ringparam = virtnet_get_ringparam,
 	.set_channels = virtnet_set_channels,
 	.get_channels = virtnet_get_channels,
+	.set_coalesce = virtnet_set_coalesce,
+	.get_coalesce = virtnet_get_coalesce,
 };
 
 #define MIN_MTU 68
@@ -2022,6 +2088,7 @@ static unsigned int features[] = {
 	VIRTIO_NET_F_GUEST_ANNOUNCE, VIRTIO_NET_F_MQ,
 	VIRTIO_NET_F_CTRL_MAC_ADDR,
 	VIRTIO_F_ANY_LAYOUT,
+	VIRTIO_NET_F_CTRL_COALESCE,
 };
 
 static struct virtio_driver virtio_net_driver = {
diff --git a/include/uapi/linux/virtio_net.h b/include/uapi/linux/virtio_net.h
index 172a7f0..cdafb57 100644
--- a/include/uapi/linux/virtio_net.h
+++ b/include/uapi/linux/virtio_net.h
@@ -33,6 +33,7 @@
 /* The feature bitmap for virtio net */
 #define VIRTIO_NET_F_CSUM	0	/* Host handles pkts w/ partial csum */
 #define VIRTIO_NET_F_GUEST_CSUM	1	/* Guest handles pkts w/ partial csum */
+#define VIRTIO_NET_F_CTRL_COALESCE 3	/* Set coalescing */
 #define VIRTIO_NET_F_MAC	5	/* Host has given MAC address. */
 #define VIRTIO_NET_F_GSO	6	/* Host handles pkts w/ any GSO type */
 #define VIRTIO_NET_F_GUEST_TSO4	7	/* Guest can handle TSOv4 in. */
@@ -201,4 +202,15 @@ struct virtio_net_ctrl_mq {
  #define VIRTIO_NET_CTRL_MQ_VQ_PAIRS_MIN        1
  #define VIRTIO_NET_CTRL_MQ_VQ_PAIRS_MAX        0x8000
 
+struct virtio_net_ctrl_coalesce {
+	__u32 coalesce_usecs;
+	__u32 max_coalesced_frames;
+};
+
+#define VIRTIO_NET_CTRL_COALESCE 6
+ #define VIRTIO_NET_CTRL_COALESCE_TX_SET 0
+ #define VIRTIO_NET_CTRL_COALESCE_TX_GET 1
+ #define VIRTIO_NET_CTRL_COALESCE_RX_SET 2
+ #define VIRTIO_NET_CTRL_COALESCE_RX_GET 3
+
 #endif /* _LINUX_VIRTIO_NET_H */
-- 
1.8.3.1

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