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From: Maxime Coquelin <maxime.coquelin@redhat.com>
To: tiwei.bie@intel.com, zhihong.wang@intel.com, dev@dpdk.org
Cc: Maxime Coquelin <maxime.coquelin@redhat.com>
Subject: [dpdk-dev] [PATCH v3 7/7] vhost: improve prefetching in enqueue path
Date: Wed, 27 Jun 2018 16:49:59 +0200	[thread overview]
Message-ID: <20180627144959.17277-8-maxime.coquelin@redhat.com> (raw)
In-Reply-To: <20180627144959.17277-1-maxime.coquelin@redhat.com>

This is an optimization to prefetch next buffer while the
current one is being processed.

Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
---
 lib/librte_vhost/virtio_net.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/lib/librte_vhost/virtio_net.c b/lib/librte_vhost/virtio_net.c
index ff6fa8d61..81377e79a 100644
--- a/lib/librte_vhost/virtio_net.c
+++ b/lib/librte_vhost/virtio_net.c
@@ -393,6 +393,9 @@ copy_mbuf_to_desc(struct virtio_net *dev, struct vhost_virtqueue *vq,
 	buf_iova = buf_vec[vec_idx].buf_iova;
 	buf_len = buf_vec[vec_idx].buf_len;
 
+	if (nr_vec > 1)
+		rte_prefetch0((void *)(uintptr_t)buf_vec[1].buf_addr);
+
 	if (unlikely(buf_len < dev->vhost_hlen && nr_vec <= 1)) {
 		error = -1;
 		goto out;
@@ -404,7 +407,6 @@ copy_mbuf_to_desc(struct virtio_net *dev, struct vhost_virtqueue *vq,
 		hdr = &tmp_hdr;
 	else
 		hdr = (struct virtio_net_hdr_mrg_rxbuf *)(uintptr_t)hdr_addr;
-	rte_prefetch0((void *)(uintptr_t)hdr_addr);
 
 	VHOST_LOG_DEBUG(VHOST_DATA, "(%d) RX: num merge buffers %d\n",
 		dev->vid, num_buffers);
@@ -436,8 +438,10 @@ copy_mbuf_to_desc(struct virtio_net *dev, struct vhost_virtqueue *vq,
 			buf_iova = buf_vec[vec_idx].buf_iova;
 			buf_len = buf_vec[vec_idx].buf_len;
 
-			/* Prefetch buffer address. */
-			rte_prefetch0((void *)(uintptr_t)buf_addr);
+			/* Prefetch next buffer address. */
+			if (vec_idx + 1 < nr_vec)
+				rte_prefetch0((void *)(uintptr_t)
+						buf_vec[vec_idx + 1].buf_addr);
 			buf_offset = 0;
 			buf_avail  = buf_len;
 		}
@@ -579,6 +583,8 @@ virtio_dev_rx(struct virtio_net *dev, uint16_t queue_id,
 			break;
 		}
 
+		rte_prefetch0((void *)(uintptr_t)buf_vec[0].buf_addr);
+
 		VHOST_LOG_DEBUG(VHOST_DATA, "(%d) current index %d | end index %d\n",
 			dev->vid, vq->last_avail_idx,
 			vq->last_avail_idx + num_buffers);
-- 
2.14.4

      parent reply	other threads:[~2018-06-27 14:50 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-06-27 14:49 [dpdk-dev] [PATCH v3 0/7] vhost: generalize buffer vectors Maxime Coquelin
2018-06-27 14:49 ` [dpdk-dev] [PATCH v3 1/7] vhost: use shadow used ring in dequeue path Maxime Coquelin
2018-07-03  3:28   ` Tiwei Bie
2018-07-03  5:53     ` Maxime Coquelin
2018-06-27 14:49 ` [dpdk-dev] [PATCH v3 2/7] vhost: make gpa to hpa failure an error Maxime Coquelin
2018-07-03  4:45   ` Tiwei Bie
2018-07-03  5:51     ` Maxime Coquelin
2018-06-27 14:49 ` [dpdk-dev] [PATCH v3 3/7] vhost: use buffer vectors in dequeue path Maxime Coquelin
2018-06-27 14:49 ` [dpdk-dev] [PATCH v3 4/7] vhost: translate iovas at vectors fill time Maxime Coquelin
2018-06-27 14:49 ` [dpdk-dev] [PATCH v3 5/7] vhost: improve prefetching in dequeue path Maxime Coquelin
2018-06-27 14:49 ` [dpdk-dev] [PATCH v3 6/7] vhost: prefetch first descriptor " Maxime Coquelin
2018-06-27 14:49 ` Maxime Coquelin [this message]

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