[RFC,4/6] virtio-net: support rx netdim

Commit Message

Heng Qi Aug. 1, 2023, 8:22 a.m. UTC

By comparing the traffic information in the complete napi processes,
let the virtio-net driver automatically adjust the coalescing
moderation parameters of each receive queue.

Signed-off-by: Heng Qi <[e-mail]>
---
 drivers/net/virtio_net.c | 97 ++++++++++++++++++++++++++++++++++------
 1 file changed, 84 insertions(+), 13 deletions(-)

Patch

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 91b284567c96..069e68a52598 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -19,6 +19,7 @@ 
 #include <linux/average.h>
 #include <linux/filter.h>
 #include <linux/kernel.h>
+#include <linux/dim.h>
 #include <net/route.h>
 #include <net/xdp.h>
 #include <net/net_failover.h>
@@ -163,8 +164,14 @@  struct receive_queue {
 
 	struct virtnet_rq_stats stats;
 
+	/* The number of rx notifications */
+	u16 calls;
+
 	struct virtnet_interrupt_coalesce intr_coal;
 
+	/* Dynamic Iterrupt Moderation */
+	struct dim dim;
+
 	/* Chain pages by the private ptr. */
 	struct page *pages;
 
@@ -290,6 +297,9 @@  struct virtnet_info {
 	u8 duplex;
 	u32 speed;
 
+	/* Is dynamic interrupt moderation enabled? */
+	bool rx_dim_enabled;
+
 	/* Interrupt coalescing settings */
 	struct virtnet_interrupt_coalesce intr_coal_tx;
 	struct virtnet_interrupt_coalesce intr_coal_rx;
@@ -1821,6 +1831,7 @@  static void skb_recv_done(struct virtqueue *rvq)
 	struct virtnet_info *vi = rvq->vdev->priv;
 	struct receive_queue *rq = &vi->rq[vq2rxq(rvq)];
 
+	rq->calls++;
 	virtqueue_napi_schedule(&rq->napi, rvq);
 }
 
@@ -1958,6 +1969,21 @@  static void virtnet_poll_cleantx(struct receive_queue *rq)
 	}
 }
 
+static void virtnet_rx_dim_work(struct work_struct *work);
+
+static void virtnet_rx_dim_update(struct virtnet_info *vi, struct receive_queue *rq)
+{
+	struct virtnet_rq_stats *stats = &rq->stats;
+	struct dim_sample cur_sample = {};
+
+	u64_stats_update_begin(&rq->stats.syncp);
+	dim_update_sample(rq->calls, stats->packets,
+			  stats->bytes, &cur_sample);
+	u64_stats_update_end(&rq->stats.syncp);
+
+	net_dim(&rq->dim, cur_sample);
+}
+
 static int virtnet_poll(struct napi_struct *napi, int budget)
 {
 	struct receive_queue *rq =
@@ -1966,6 +1992,7 @@  static int virtnet_poll(struct napi_struct *napi, int budget)
 	struct send_queue *sq;
 	unsigned int received;
 	unsigned int xdp_xmit = 0;
+	bool napi_complete;
 
 	virtnet_poll_cleantx(rq);
 
@@ -1975,8 +2002,11 @@  static int virtnet_poll(struct napi_struct *napi, int budget)
 		xdp_do_flush();
 
 	/* Out of packets? */
-	if (received < budget)
-		virtqueue_napi_complete(napi, rq->vq, received);
+	if (received < budget) {
+		napi_complete = virtqueue_napi_complete(napi, rq->vq, received);
+		if (napi_complete && vi->rx_dim_enabled)
+			virtnet_rx_dim_update(vi, rq);
+	}
 
 	if (xdp_xmit & VIRTIO_XDP_TX) {
 		sq = virtnet_xdp_get_sq(vi);
@@ -1996,6 +2026,7 @@  static void virtnet_disable_queue_pair(struct virtnet_info *vi, int qp_index)
 	virtnet_napi_tx_disable(&vi->sq[qp_index].napi);
 	napi_disable(&vi->rq[qp_index].napi);
 	xdp_rxq_info_unreg(&vi->rq[qp_index].xdp_rxq);
+	cancel_work_sync(&vi->rq[qp_index].dim.work);
 }
 
 static int virtnet_enable_queue_pair(struct virtnet_info *vi, int qp_index)
@@ -2013,6 +2044,9 @@  static int virtnet_enable_queue_pair(struct virtnet_info *vi, int qp_index)
 	if (err < 0)
 		goto err_xdp_reg_mem_model;
 
+	INIT_WORK(&vi->rq[qp_index].dim.work, virtnet_rx_dim_work);
+	vi->rq[qp_index].dim.mode = DIM_CQ_PERIOD_MODE_START_FROM_EQE;
+
 	virtnet_napi_enable(vi->rq[qp_index].vq, &vi->rq[qp_index].napi);
 	virtnet_napi_tx_enable(vi, vi->sq[qp_index].vq, &vi->sq[qp_index].napi);
 
@@ -3077,20 +3111,33 @@  static int virtnet_send_tx_notf_coal_cmds(struct virtnet_info *vi,
 static int virtnet_send_rx_notf_coal_cmds(struct virtnet_info *vi,
 					  struct ethtool_coalesce *ec)
 {
+	bool rx_ctrl_dim_on = !!ec->use_adaptive_rx_coalesce;
 	struct scatterlist sgs_rx;
 
-	vi->ctrl->coal_rx.rx_usecs = cpu_to_le32(ec->rx_coalesce_usecs);
-	vi->ctrl->coal_rx.rx_max_packets = cpu_to_le32(ec->rx_max_coalesced_frames);
-	sg_init_one(&sgs_rx, &vi->ctrl->coal_rx, sizeof(vi->ctrl->coal_rx));
-
-	if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_NOTF_COAL,
-				  VIRTIO_NET_CTRL_NOTF_COAL_RX_SET,
-				  &sgs_rx))
+	if (rx_ctrl_dim_on && (ec->rx_coalesce_usecs != vi->intr_coal_rx.max_usecs ||
+			       ec->rx_max_coalesced_frames != vi->intr_coal_rx.max_packets))
 		return -EINVAL;
 
-	/* Save parameters */
-	vi->intr_coal_rx.max_usecs = ec->rx_coalesce_usecs;
-	vi->intr_coal_rx.max_packets = ec->rx_max_coalesced_frames;
+	if (rx_ctrl_dim_on) {
+		if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_VQ_NOTF_COAL))
+			vi->rx_dim_enabled = true;
+		else
+			return -EOPNOTSUPP;
+	}  else if (!rx_ctrl_dim_on) {
+		vi->rx_dim_enabled = false;
+		vi->ctrl->coal_rx.rx_usecs = cpu_to_le32(ec->rx_coalesce_usecs);
+		vi->ctrl->coal_rx.rx_max_packets = cpu_to_le32(ec->rx_max_coalesced_frames);
+		sg_init_one(&sgs_rx, &vi->ctrl->coal_rx, sizeof(vi->ctrl->coal_rx));
+
+		if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_NOTF_COAL,
+					  VIRTIO_NET_CTRL_NOTF_COAL_RX_SET,
+					  &sgs_rx))
+			return -EINVAL;
+
+		/* Save parameters */
+		vi->intr_coal_rx.max_usecs = ec->rx_coalesce_usecs;
+		vi->intr_coal_rx.max_packets = ec->rx_max_coalesced_frames;
+	}
 
 	return 0;
 }
@@ -3172,6 +3219,9 @@  static int virtnet_send_notf_coal_vq_cmds(struct virtnet_info *vi,
 	int err;
 
 	if (ec->rx_coalesce_usecs || ec->rx_max_coalesced_frames) {
+		if (vi->rx_dim_enabled)
+			return -EBUSY;
+
 		err = virtnet_send_rx_notf_coal_vq_cmd(vi, queue,
 						       ec->rx_coalesce_usecs,
 						       ec->rx_max_coalesced_frames);
@@ -3190,6 +3240,27 @@  static int virtnet_send_notf_coal_vq_cmds(struct virtnet_info *vi,
 	return 0;
 }
 
+static void virtnet_rx_dim_work(struct work_struct *work)
+{
+	struct dim *dim = container_of(work, struct dim, work);
+	struct receive_queue *rq = container_of(dim,
+			struct receive_queue, dim);
+	struct virtnet_info *vi = rq->vq->vdev->priv;
+	struct net_device *dev = vi->dev;
+	struct dim_cq_moder update_moder;
+	int qnum = rq - vi->rq, err;
+
+	update_moder = net_dim_get_rx_moderation(dim->mode, dim->profile_ix);
+	err = virtnet_send_rx_notf_coal_vq_cmd(vi, qnum,
+					       update_moder.usec,
+					       update_moder.pkts);
+	if (err)
+		pr_debug("%s: Failed to send dim parameters on rxq%d\n",
+				dev->name, (int)(rq - vi->rq));
+
+	dim->state = DIM_START_MEASURE;
+}
+
 static int virtnet_coal_params_supported(struct ethtool_coalesce *ec)
 {
 	/* usecs coalescing is supported only if VIRTIO_NET_F_NOTF_COAL
@@ -3453,7 +3524,7 @@  static int virtnet_set_rxnfc(struct net_device *dev, struct ethtool_rxnfc *info)
 
 static const struct ethtool_ops virtnet_ethtool_ops = {
 	.supported_coalesce_params = ETHTOOL_COALESCE_MAX_FRAMES |
-		ETHTOOL_COALESCE_USECS,
+		ETHTOOL_COALESCE_USECS | ETHTOOL_COALESCE_USE_ADAPTIVE_RX,
 	.get_drvinfo = virtnet_get_drvinfo,
 	.get_link = ethtool_op_get_link,
 	.get_ringparam = virtnet_get_ringparam,