patches for DPDK stable branches
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From: Maxime Coquelin <maxime.coquelin@redhat.com>
To: dev@dpdk.org, chenbo.xia@intel.com, amorenoz@dpdk.org,
	jasowang@redhat.com
Cc: Maxime Coquelin <maxime.coquelin@redhat.com>, stable@dpdk.org
Subject: [dpdk-stable] [PATCH 21.02 v1] net/virtio: fix memory init with vDPA backend
Date: Tue, 24 Nov 2020 13:45:07 +0100
Message-ID: <20201124124507.139984-1-maxime.coquelin@redhat.com> (raw)

This patch fixes an overhead met with mlx5-vdpa Kernel
driver, where for every page in the mapped area, all the
memory tables gets updated. For example, with 2MB hugepages,
a single IOTLB_UPDATE for a 1GB region causes 512 memory
updates on mlx5-vdpa side.

Using batching mode, the mlx5 driver will only trigger a
single memory update for all the IOTLB updates that happen
between the batch begin and batch end commands.

Fixes: 6b901437056e ("net/virtio: introduce vhost-vDPA backend")
Cc: stable@dpdk.org

Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
---
 drivers/net/virtio/virtio_user/vhost_vdpa.c | 90 +++++++++++++++++++--
 1 file changed, 85 insertions(+), 5 deletions(-)

diff --git a/drivers/net/virtio/virtio_user/vhost_vdpa.c b/drivers/net/virtio/virtio_user/vhost_vdpa.c
index c7b9349fc8..6d0200516d 100644
--- a/drivers/net/virtio/virtio_user/vhost_vdpa.c
+++ b/drivers/net/virtio/virtio_user/vhost_vdpa.c
@@ -66,6 +66,8 @@ struct vhost_iotlb_msg {
 #define VHOST_IOTLB_UPDATE         2
 #define VHOST_IOTLB_INVALIDATE     3
 #define VHOST_IOTLB_ACCESS_FAIL    4
+#define VHOST_IOTLB_BATCH_BEGIN    5
+#define VHOST_IOTLB_BATCH_END      6
 	uint8_t type;
 };
 
@@ -80,6 +82,40 @@ struct vhost_msg {
 	};
 };
 
+static int
+vhost_vdpa_iotlb_batch_begin(struct virtio_user_dev *dev)
+{
+	struct vhost_msg msg = {};
+
+	msg.type = VHOST_IOTLB_MSG_V2;
+	msg.iotlb.type = VHOST_IOTLB_BATCH_BEGIN;
+
+	if (write(dev->vhostfd, &msg, sizeof(msg)) != sizeof(msg)) {
+		PMD_DRV_LOG(ERR, "Failed to send IOTLB batch begin (%s)",
+				strerror(errno));
+		return -1;
+	}
+
+	return 0;
+}
+
+static int
+vhost_vdpa_iotlb_batch_end(struct virtio_user_dev *dev)
+{
+	struct vhost_msg msg = {};
+
+	msg.type = VHOST_IOTLB_MSG_V2;
+	msg.iotlb.type = VHOST_IOTLB_BATCH_END;
+
+	if (write(dev->vhostfd, &msg, sizeof(msg)) != sizeof(msg)) {
+		PMD_DRV_LOG(ERR, "Failed to send IOTLB batch end (%s)",
+				strerror(errno));
+		return -1;
+	}
+
+	return 0;
+}
+
 static int
 vhost_vdpa_dma_map(struct virtio_user_dev *dev, void *addr,
 				  uint64_t iova, size_t len)
@@ -122,6 +158,39 @@ vhost_vdpa_dma_unmap(struct virtio_user_dev *dev, __rte_unused void *addr,
 	return 0;
 }
 
+static int
+vhost_vdpa_dma_map_batch(struct virtio_user_dev *dev, void *addr,
+				  uint64_t iova, size_t len)
+{
+	int ret;
+
+	if (vhost_vdpa_iotlb_batch_begin(dev) < 0)
+		return -1;
+
+	ret = vhost_vdpa_dma_map(dev, addr, iova, len);
+
+	if (vhost_vdpa_iotlb_batch_end(dev) < 0)
+		return -1;
+
+	return ret;
+}
+
+static int
+vhost_vdpa_dma_unmap_batch(struct virtio_user_dev *dev, void *addr,
+				  uint64_t iova, size_t len)
+{
+	int ret;
+
+	if (vhost_vdpa_iotlb_batch_begin(dev) < 0)
+		return -1;
+
+	ret = vhost_vdpa_dma_unmap(dev, addr, iova, len);
+
+	if (vhost_vdpa_iotlb_batch_end(dev) < 0)
+		return -1;
+
+	return ret;
+}
 
 static int
 vhost_vdpa_map_contig(const struct rte_memseg_list *msl,
@@ -159,21 +228,32 @@ vhost_vdpa_map(const struct rte_memseg_list *msl, const struct rte_memseg *ms,
 static int
 vhost_vdpa_dma_map_all(struct virtio_user_dev *dev)
 {
+	int ret;
+
+	if (vhost_vdpa_iotlb_batch_begin(dev) < 0)
+		return -1;
+
 	vhost_vdpa_dma_unmap(dev, NULL, 0, SIZE_MAX);
 
 	if (rte_eal_iova_mode() == RTE_IOVA_VA) {
 		/* with IOVA as VA mode, we can get away with mapping contiguous
 		 * chunks rather than going page-by-page.
 		 */
-		int ret = rte_memseg_contig_walk_thread_unsafe(
+		ret = rte_memseg_contig_walk_thread_unsafe(
 				vhost_vdpa_map_contig, dev);
 		if (ret)
-			return ret;
+			goto batch_end;
 		/* we have to continue the walk because we've skipped the
 		 * external segments during the config walk.
 		 */
 	}
-	return rte_memseg_walk_thread_unsafe(vhost_vdpa_map, dev);
+	ret = rte_memseg_walk_thread_unsafe(vhost_vdpa_map, dev);
+
+batch_end:
+	if (vhost_vdpa_iotlb_batch_end(dev) < 0)
+		return -1;
+
+	return ret;
 }
 
 /* with below features, vhost vdpa does not need to do the checksum and TSO,
@@ -293,6 +373,6 @@ struct virtio_user_backend_ops virtio_ops_vdpa = {
 	.setup = vhost_vdpa_setup,
 	.send_request = vhost_vdpa_ioctl,
 	.enable_qp = vhost_vdpa_enable_queue_pair,
-	.dma_map = vhost_vdpa_dma_map,
-	.dma_unmap = vhost_vdpa_dma_unmap,
+	.dma_map = vhost_vdpa_dma_map_batch,
+	.dma_unmap = vhost_vdpa_dma_unmap_batch,
 };
-- 
2.26.2


             reply	other threads:[~2020-11-24 12:45 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-24 12:45 Maxime Coquelin [this message]
2020-11-24 12:45 Maxime Coquelin
2020-11-25  2:18 ` Jason Wang

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