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: sta...@dpdk.org
Signed-off-by: Maxime Coquelin <maxime.coque...@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
