enic: improve Tx packet rate

For every packet sent, a completion was being requested and the
posted_index register on the nic was being updated. Instead, request a
completion and update the posted index once per burst after all
packets have been sent by the burst function.

Signed-off-by: John Daley <johndale@cisco.com>
Acked-by: Sujith Sankar <ssujith@cisco.com>

drivers/net/enic/base/enic_vnic_wq.h

@@ -0,0 +1,79 @@
+/*
+ * Copyright 2008-2015 Cisco Systems, Inc.  All rights reserved.
+ * Copyright 2007 Nuova Systems, Inc.  All rights reserved.
+ *
+ * Copyright (c) 2015, Cisco Systems, Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in
+ * the documentation and/or other materials provided with the
+ * distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#ifndef _ENIC_VNIC_WQ_H_
+#define _ENIC_VNIC_WQ_H_
+
+#include "vnic_dev.h"
+#include "vnic_cq.h"
+
+static inline void enic_vnic_post_wq_index(struct vnic_wq *wq)
+{
+	struct vnic_wq_buf *buf = wq->to_use;
+
+	/* Adding write memory barrier prevents compiler and/or CPU
+	 * reordering, thus avoiding descriptor posting before
+	 * descriptor is initialized. Otherwise, hardware can read
+	 * stale descriptor fields.
+	*/
+	wmb();
+	iowrite32(buf->index, &wq->ctrl->posted_index);
+}
+
+static inline void enic_vnic_post_wq(struct vnic_wq *wq,
+				     void *os_buf, dma_addr_t dma_addr,
+				     unsigned int len, int sop,
+				     uint8_t desc_skip_cnt, uint8_t cq_entry,
+				     uint8_t compressed_send, uint64_t wrid)
+{
+	struct vnic_wq_buf *buf = wq->to_use;
+
+	buf->sop = sop;
+	buf->cq_entry = cq_entry;
+	buf->compressed_send = compressed_send;
+	buf->desc_skip_cnt = desc_skip_cnt;
+	buf->os_buf = os_buf;
+	buf->dma_addr = dma_addr;
+	buf->len = len;
+	buf->wr_id = wrid;
+
+	buf = buf->next;
+	if (cq_entry)
+		enic_vnic_post_wq_index(wq);
+	wq->to_use = buf;
+
+	wq->ring.desc_avail -= desc_skip_cnt;
+}
+
+#endif /* _ENIC_VNIC_WQ_H_ */

drivers/net/enic/enic.h

@@ -48,7 +48,7 @@
 
 #define DRV_NAME		"enic_pmd"
 #define DRV_DESCRIPTION		"Cisco VIC Ethernet NIC Poll-mode Driver"
-#define DRV_VERSION		"1.0.0.5"
+#define DRV_VERSION		"1.0.0.6"
 #define DRV_COPYRIGHT		"Copyright 2008-2015 Cisco Systems, Inc"
 
 #define ENIC_WQ_MAX		8
@@ -187,10 +187,12 @@ extern void enic_add_packet_filter(struct enic *enic);
 extern void enic_set_mac_address(struct enic *enic, uint8_t *mac_addr);
 extern void enic_del_mac_address(struct enic *enic);
 extern unsigned int enic_cleanup_wq(struct enic *enic, struct vnic_wq *wq);
-extern int enic_send_pkt(struct enic *enic, struct vnic_wq *wq,
-	struct rte_mbuf *tx_pkt, unsigned short len,
-	uint8_t sop, uint8_t eop,
-	uint16_t ol_flags, uint16_t vlan_tag);
+extern void enic_send_pkt(struct enic *enic, struct vnic_wq *wq,
+			  struct rte_mbuf *tx_pkt, unsigned short len,
+			  uint8_t sop, uint8_t eop, uint8_t cq_entry,
+			  uint16_t ol_flags, uint16_t vlan_tag);
+
+extern void enic_post_wq_index(struct vnic_wq *wq);
 extern int enic_poll(struct vnic_rq *rq, struct rte_mbuf **rx_pkts,
 	unsigned int budget, unsigned int *work_done);
 extern int enic_probe(struct enic *enic);

drivers/net/enic/enic_ethdev.c

@@ -488,21 +488,26 @@ static uint16_t enicpmd_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts,
 	unsigned int seg_len;
 	unsigned int inc_len;
 	unsigned int nb_segs;
-	struct rte_mbuf *tx_pkt;
+	struct rte_mbuf *tx_pkt, *next_tx_pkt;
 	struct vnic_wq *wq = (struct vnic_wq *)tx_queue;
 	struct enic *enic = vnic_dev_priv(wq->vdev);
 	unsigned short vlan_id;
 	unsigned short ol_flags;
+	uint8_t last_seg, eop;
 
 	for (index = 0; index < nb_pkts; index++) {
 		tx_pkt = *tx_pkts++;
 		inc_len = 0;
 		nb_segs = tx_pkt->nb_segs;
 		if (nb_segs > vnic_wq_desc_avail(wq)) {
+			if (index > 0)
+				enic_post_wq_index(wq);
+
 			/* wq cleanup and try again */
 			if (!enic_cleanup_wq(enic, wq) ||
-				(nb_segs > vnic_wq_desc_avail(wq)))
+				(nb_segs > vnic_wq_desc_avail(wq))) {
 				return index;
+			}
 		}
 		pkt_len = tx_pkt->pkt_len;
 		vlan_id = tx_pkt->vlan_tci;
@@ -510,14 +515,15 @@ static uint16_t enicpmd_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts,
 		for (frags = 0; inc_len < pkt_len; frags++) {
 			if (!tx_pkt)
 				break;
+			next_tx_pkt = tx_pkt->next;
 			seg_len = tx_pkt->data_len;
 			inc_len += seg_len;
-			if (enic_send_pkt(enic, wq, tx_pkt,
-				    (unsigned short)seg_len, !frags,
-				    (pkt_len == inc_len), ol_flags, vlan_id)) {
-				break;
-			}
-			tx_pkt = tx_pkt->next;
+			eop = (pkt_len == inc_len) || (!next_tx_pkt);
+			last_seg = eop &&
+				(index == ((unsigned int)nb_pkts - 1));
+			enic_send_pkt(enic, wq, tx_pkt, (unsigned short)seg_len,
+				      !frags, eop, last_seg, ol_flags, vlan_id);
+			tx_pkt = next_tx_pkt;
 		}
 	}
 

drivers/net/enic/enic_main.c

@@ -58,6 +58,7 @@
 #include "vnic_cq.h"
 #include "vnic_intr.h"
 #include "vnic_nic.h"
+#include "enic_vnic_wq.h"
 
 static inline int enic_is_sriov_vf(struct enic *enic)
 {
@@ -151,15 +152,18 @@ unsigned int enic_cleanup_wq(struct enic *enic, struct vnic_wq *wq)
 		-1 /*wq_work_to_do*/, enic_wq_service, NULL);
 }
 
+void enic_post_wq_index(struct vnic_wq *wq)
+{
+	enic_vnic_post_wq_index(wq);
+}
 
-int enic_send_pkt(struct enic *enic, struct vnic_wq *wq,
-	struct rte_mbuf *tx_pkt, unsigned short len,
-	uint8_t sop, uint8_t eop,
-	uint16_t ol_flags, uint16_t vlan_tag)
+void enic_send_pkt(struct enic *enic, struct vnic_wq *wq,
+		   struct rte_mbuf *tx_pkt, unsigned short len,
+		   uint8_t sop, uint8_t eop, uint8_t cq_entry,
+		   uint16_t ol_flags, uint16_t vlan_tag)
 {
 	struct wq_enet_desc *desc = vnic_wq_next_desc(wq);
 	uint16_t mss = 0;
-	uint8_t cq_entry = eop;
 	uint8_t vlan_tag_insert = 0;
 	uint64_t bus_addr = (dma_addr_t)
 	    (tx_pkt->buf_physaddr + RTE_PKTMBUF_HEADROOM);
@@ -190,14 +194,12 @@ int enic_send_pkt(struct enic *enic, struct vnic_wq *wq,
 		vlan_tag,
 		0 /* loopback */);
 
-	vnic_wq_post(wq, (void *)tx_pkt, bus_addr, len,
-		sop, eop,
-		1 /*desc_skip_cnt*/,
-		cq_entry,
-		0 /*compressed send*/,
-		0 /*wrid*/);
-
-	return 0;
+	enic_vnic_post_wq(wq, (void *)tx_pkt, bus_addr, len,
+			  sop,
+			  1 /*desc_skip_cnt*/,
+			  cq_entry,
+			  0 /*compressed send*/,
+			  0 /*wrid*/);
 }
 
 void enic_dev_stats_clear(struct enic *enic)