Thread (8 messages) 8 messages, 2 authors, 2018-12-21
STALE2736d REVIEWED: 2 (0M)

[PATCH v3 3/3] net/virtio: improve batching in mergeable path

From: Maxime Coquelin <hidden>
Date: 2018-12-20 17:27:37
Subsystem: networking drivers, the rest · Maintainers: Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds

This patch improves both descriptors dequeue and refill,
by using the same batching strategy as done in in-order path.

Signed-off-by: Maxime Coquelin <redacted>
Tested-by: Jens Freimann <redacted>
Reviewed-by: Jens Freimann <redacted>
---
 drivers/net/virtio/virtio_rxtx.c | 239 +++++++++++++++++--------------
 1 file changed, 129 insertions(+), 110 deletions(-)
diff --git a/drivers/net/virtio/virtio_rxtx.c b/drivers/net/virtio/virtio_rxtx.c
index 58376ced3..1cfa2f0d6 100644
--- a/drivers/net/virtio/virtio_rxtx.c
+++ b/drivers/net/virtio/virtio_rxtx.c
@@ -353,41 +353,44 @@ virtqueue_enqueue_refill_inorder(struct virtqueue *vq,
 }
 
 static inline int
-virtqueue_enqueue_recv_refill(struct virtqueue *vq, struct rte_mbuf *cookie)
+virtqueue_enqueue_recv_refill(struct virtqueue *vq, struct rte_mbuf **cookie,
+				uint16_t num)
 {
 	struct vq_desc_extra *dxp;
 	struct virtio_hw *hw = vq->hw;
-	struct vring_desc *start_dp;
-	uint16_t needed = 1;
-	uint16_t head_idx, idx;
+	struct vring_desc *start_dp = vq->vq_ring.desc;
+	uint16_t idx, i;
 
 	if (unlikely(vq->vq_free_cnt == 0))
 		return -ENOSPC;
-	if (unlikely(vq->vq_free_cnt < needed))
+	if (unlikely(vq->vq_free_cnt < num))
 		return -EMSGSIZE;
 
-	head_idx = vq->vq_desc_head_idx;
-	if (unlikely(head_idx >= vq->vq_nentries))
+	if (unlikely(vq->vq_desc_head_idx >= vq->vq_nentries))
 		return -EFAULT;
 
-	idx = head_idx;
-	dxp = &vq->vq_descx[idx];
-	dxp->cookie = (void *)cookie;
-	dxp->ndescs = needed;
+	for (i = 0; i < num; i++) {
+		idx = vq->vq_desc_head_idx;
+		dxp = &vq->vq_descx[idx];
+		dxp->cookie = (void *)cookie[i];
+		dxp->ndescs = 1;
 
-	start_dp = vq->vq_ring.desc;
-	start_dp[idx].addr =
-		VIRTIO_MBUF_ADDR(cookie, vq) +
-		RTE_PKTMBUF_HEADROOM - hw->vtnet_hdr_size;
-	start_dp[idx].len =
-		cookie->buf_len - RTE_PKTMBUF_HEADROOM + hw->vtnet_hdr_size;
-	start_dp[idx].flags =  VRING_DESC_F_WRITE;
-	idx = start_dp[idx].next;
-	vq->vq_desc_head_idx = idx;
-	if (vq->vq_desc_head_idx == VQ_RING_DESC_CHAIN_END)
-		vq->vq_desc_tail_idx = idx;
-	vq->vq_free_cnt = (uint16_t)(vq->vq_free_cnt - needed);
-	vq_update_avail_ring(vq, head_idx);
+		start_dp[idx].addr =
+			VIRTIO_MBUF_ADDR(cookie[i], vq) +
+			RTE_PKTMBUF_HEADROOM - hw->vtnet_hdr_size;
+		start_dp[idx].len =
+			cookie[i]->buf_len - RTE_PKTMBUF_HEADROOM +
+			hw->vtnet_hdr_size;
+		start_dp[idx].flags = VRING_DESC_F_WRITE;
+		vq->vq_desc_head_idx = start_dp[idx].next;
+		vq_update_avail_ring(vq, idx);
+		if (vq->vq_desc_head_idx == VQ_RING_DESC_CHAIN_END) {
+			vq->vq_desc_tail_idx = vq->vq_desc_head_idx;
+			break;
+		}
+	}
+
+	vq->vq_free_cnt = (uint16_t)(vq->vq_free_cnt - num);
 
 	return 0;
 }
@@ -892,7 +895,8 @@ virtio_dev_rx_queue_setup_finish(struct rte_eth_dev *dev, uint16_t queue_idx)
 				error = virtqueue_enqueue_recv_refill_packed(vq,
 						&m, 1);
 			else
-				error = virtqueue_enqueue_recv_refill(vq, m);
+				error = virtqueue_enqueue_recv_refill(vq,
+						&m, 1);
 			if (error) {
 				rte_pktmbuf_free(m);
 				break;
@@ -991,7 +995,7 @@ virtio_discard_rxbuf(struct virtqueue *vq, struct rte_mbuf *m)
 	if (vtpci_packed_queue(vq->hw))
 		error = virtqueue_enqueue_recv_refill_packed(vq, &m, 1);
 	else
-		error = virtqueue_enqueue_recv_refill(vq, m);
+		error = virtqueue_enqueue_recv_refill(vq, &m, 1);
 
 	if (unlikely(error)) {
 		RTE_LOG(ERR, PMD, "cannot requeue discarded mbuf");
@@ -1211,7 +1215,7 @@ virtio_recv_pkts(void *rx_queue, struct rte_mbuf **rx_pkts, uint16_t nb_pkts)
 			dev->data->rx_mbuf_alloc_failed++;
 			break;
 		}
-		error = virtqueue_enqueue_recv_refill(vq, new_mbuf);
+		error = virtqueue_enqueue_recv_refill(vq, &new_mbuf, 1);
 		if (unlikely(error)) {
 			rte_pktmbuf_free(new_mbuf);
 			break;
@@ -1528,19 +1532,18 @@ virtio_recv_mergeable_pkts(void *rx_queue,
 	struct virtnet_rx *rxvq = rx_queue;
 	struct virtqueue *vq = rxvq->vq;
 	struct virtio_hw *hw = vq->hw;
-	struct rte_mbuf *rxm, *new_mbuf;
-	uint16_t nb_used, num, nb_rx;
+	struct rte_mbuf *rxm;
+	struct rte_mbuf *prev;
+	uint16_t nb_used, num, nb_rx = 0;
 	uint32_t len[VIRTIO_MBUF_BURST_SZ];
 	struct rte_mbuf *rcv_pkts[VIRTIO_MBUF_BURST_SZ];
-	struct rte_mbuf *prev;
 	int error;
-	uint32_t i, nb_enqueued;
-	uint32_t seg_num;
-	uint16_t extra_idx;
-	uint32_t seg_res;
-	uint32_t hdr_size;
+	uint32_t nb_enqueued = 0;
+	uint32_t seg_num = 0;
+	uint32_t seg_res = 0;
+	uint32_t hdr_size = hw->vtnet_hdr_size;
+	int32_t i;
 
-	nb_rx = 0;
 	if (unlikely(hw->started == 0))
 		return nb_rx;
 
@@ -1550,31 +1553,25 @@ virtio_recv_mergeable_pkts(void *rx_queue,
 
 	PMD_RX_LOG(DEBUG, "used:%d", nb_used);
 
-	i = 0;
-	nb_enqueued = 0;
-	seg_num = 0;
-	extra_idx = 0;
-	seg_res = 0;
-	hdr_size = hw->vtnet_hdr_size;
-
-	while (i < nb_used) {
-		struct virtio_net_hdr_mrg_rxbuf *header;
+	num = likely(nb_used <= nb_pkts) ? nb_used : nb_pkts;
+	if (unlikely(num > VIRTIO_MBUF_BURST_SZ))
+		num = VIRTIO_MBUF_BURST_SZ;
+	if (likely(num > DESC_PER_CACHELINE))
+		num = num - ((vq->vq_used_cons_idx + num) %
+				DESC_PER_CACHELINE);
 
-		if (nb_rx == nb_pkts)
-			break;
 
-		num = virtqueue_dequeue_burst_rx(vq, rcv_pkts, len, 1);
-		if (num != 1)
-			continue;
+	num = virtqueue_dequeue_burst_rx(vq, rcv_pkts, len, num);
 
-		i++;
+	for (i = 0; i < num; i++) {
+		struct virtio_net_hdr_mrg_rxbuf *header;
 
 		PMD_RX_LOG(DEBUG, "dequeue:%d", num);
-		PMD_RX_LOG(DEBUG, "packet len:%d", len[0]);
+		PMD_RX_LOG(DEBUG, "packet len:%d", len[i]);
 
-		rxm = rcv_pkts[0];
+		rxm = rcv_pkts[i];
 
-		if (unlikely(len[0] < hdr_size + ETHER_HDR_LEN)) {
+		if (unlikely(len[i] < hdr_size + ETHER_HDR_LEN)) {
 			PMD_RX_LOG(ERR, "Packet drop");
 			nb_enqueued++;
 			virtio_discard_rxbuf(vq, rxm);
@@ -1582,10 +1579,10 @@ virtio_recv_mergeable_pkts(void *rx_queue,
 			continue;
 		}
 
-		header = (struct virtio_net_hdr_mrg_rxbuf *)((char *)rxm->buf_addr +
-			RTE_PKTMBUF_HEADROOM - hdr_size);
+		header = (struct virtio_net_hdr_mrg_rxbuf *)
+			 ((char *)rxm->buf_addr + RTE_PKTMBUF_HEADROOM
+			 - hdr_size);
 		seg_num = header->num_buffers;
-
 		if (seg_num == 0)
 			seg_num = 1;
 
@@ -1593,10 +1590,11 @@ virtio_recv_mergeable_pkts(void *rx_queue,
 		rxm->nb_segs = seg_num;
 		rxm->ol_flags = 0;
 		rxm->vlan_tci = 0;
-		rxm->pkt_len = (uint32_t)(len[0] - hdr_size);
-		rxm->data_len = (uint16_t)(len[0] - hdr_size);
+		rxm->pkt_len = (uint32_t)(len[i] - hdr_size);
+		rxm->data_len = (uint16_t)(len[i] - hdr_size);
 
 		rxm->port = rxvq->port_id;
+
 		rx_pkts[nb_rx] = rxm;
 		prev = rxm;
 
@@ -1607,75 +1605,96 @@ virtio_recv_mergeable_pkts(void *rx_queue,
 			continue;
 		}
 
+		if (hw->vlan_strip)
+			rte_vlan_strip(rx_pkts[nb_rx]);
+
 		seg_res = seg_num - 1;
 
-		while (seg_res != 0) {
-			/*
-			 * Get extra segments for current uncompleted packet.
-			 */
-			uint16_t  rcv_cnt =
-				RTE_MIN(seg_res, RTE_DIM(rcv_pkts));
-			if (likely(VIRTQUEUE_NUSED(vq) >= rcv_cnt)) {
-				uint32_t rx_num =
-					virtqueue_dequeue_burst_rx(vq,
-					rcv_pkts, len, rcv_cnt);
-				i += rx_num;
-				rcv_cnt = rx_num;
-			} else {
-				PMD_RX_LOG(ERR,
-					   "No enough segments for packet.");
-				nb_enqueued++;
-				virtio_discard_rxbuf(vq, rxm);
-				rxvq->stats.errors++;
-				break;
-			}
+		/* Merge remaining segments */
+		while (seg_res != 0 && i < (num - 1)) {
+			i++;
+
+			rxm = rcv_pkts[i];
+			rxm->data_off = RTE_PKTMBUF_HEADROOM - hdr_size;
+			rxm->pkt_len = (uint32_t)(len[i]);
+			rxm->data_len = (uint16_t)(len[i]);
+
+			rx_pkts[nb_rx]->pkt_len += (uint32_t)(len[i]);
+			rx_pkts[nb_rx]->data_len += (uint16_t)(len[i]);
+
+			if (prev)
+				prev->next = rxm;
+
+			prev = rxm;
+			seg_res -= 1;
+		}
+
+		if (!seg_res) {
+			virtio_rx_stats_updated(rxvq, rx_pkts[nb_rx]);
+			nb_rx++;
+		}
+	}
+
+	/* Last packet still need merge segments */
+	while (seg_res != 0) {
+		uint16_t rcv_cnt = RTE_MIN((uint16_t)seg_res,
+					VIRTIO_MBUF_BURST_SZ);
 
-			extra_idx = 0;
+		prev = rcv_pkts[nb_rx];
+		if (likely(VIRTQUEUE_NUSED(vq) >= rcv_cnt)) {
+			num = virtqueue_dequeue_burst_rx(vq, rcv_pkts, len,
+							   rcv_cnt);
+			uint16_t extra_idx = 0;
 
+			rcv_cnt = num;
 			while (extra_idx < rcv_cnt) {
 				rxm = rcv_pkts[extra_idx];
-
-				rxm->data_off = RTE_PKTMBUF_HEADROOM - hdr_size;
+				rxm->data_off =
+					RTE_PKTMBUF_HEADROOM - hdr_size;
 				rxm->pkt_len = (uint32_t)(len[extra_idx]);
 				rxm->data_len = (uint16_t)(len[extra_idx]);
-
-				if (prev)
-					prev->next = rxm;
-
+				prev->next = rxm;
 				prev = rxm;
-				rx_pkts[nb_rx]->pkt_len += rxm->pkt_len;
-				extra_idx++;
+				rx_pkts[nb_rx]->pkt_len += len[extra_idx];
+				rx_pkts[nb_rx]->data_len += len[extra_idx];
+				extra_idx += 1;
 			};
 			seg_res -= rcv_cnt;
-		}
-
-		if (hw->vlan_strip)
-			rte_vlan_strip(rx_pkts[nb_rx]);
-
-		VIRTIO_DUMP_PACKET(rx_pkts[nb_rx],
-			rx_pkts[nb_rx]->data_len);
 
-		virtio_update_packet_stats(&rxvq->stats, rx_pkts[nb_rx]);
-		nb_rx++;
+			if (!seg_res) {
+				virtio_rx_stats_updated(rxvq, rx_pkts[nb_rx]);
+				nb_rx++;
+			}
+		} else {
+			PMD_RX_LOG(ERR,
+					"No enough segments for packet.");
+			virtio_discard_rxbuf(vq, prev);
+			rxvq->stats.errors++;
+			break;
+		}
 	}
 
 	rxvq->stats.packets += nb_rx;
 
 	/* Allocate new mbuf for the used descriptor */
-	while (likely(!virtqueue_full(vq))) {
-		new_mbuf = rte_mbuf_raw_alloc(rxvq->mpool);
-		if (unlikely(new_mbuf == NULL)) {
-			struct rte_eth_dev *dev
-				= &rte_eth_devices[rxvq->port_id];
-			dev->data->rx_mbuf_alloc_failed++;
-			break;
-		}
-		error = virtqueue_enqueue_recv_refill(vq, new_mbuf);
-		if (unlikely(error)) {
-			rte_pktmbuf_free(new_mbuf);
-			break;
+	if (likely(!virtqueue_full(vq))) {
+		/* free_cnt may include mrg descs */
+		uint16_t free_cnt = vq->vq_free_cnt;
+		struct rte_mbuf *new_pkts[free_cnt];
+
+		if (!rte_pktmbuf_alloc_bulk(rxvq->mpool, new_pkts, free_cnt)) {
+			error = virtqueue_enqueue_recv_refill(vq, new_pkts,
+					free_cnt);
+			if (unlikely(error)) {
+				for (i = 0; i < free_cnt; i++)
+					rte_pktmbuf_free(new_pkts[i]);
+			}
+			nb_enqueued += free_cnt;
+		} else {
+			struct rte_eth_dev *dev =
+				&rte_eth_devices[rxvq->port_id];
+			dev->data->rx_mbuf_alloc_failed += free_cnt;
 		}
-		nb_enqueued++;
 	}
 
 	if (likely(nb_enqueued)) {
-- 
2.17.2
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