From: Jason Wang <jasowang@redhat.com>
To: Maxime Coquelin <maxime.coquelin@redhat.com>,
dev@dpdk.org, chenbo.xia@intel.com, amorenoz@redhat.com
Cc: stable@dpdk.org
Subject: Re: [dpdk-stable] [PATCH 21.02 v1] net/virtio: fix memory init with vDPA backend
Date: Wed, 25 Nov 2020 10:18:01 +0800 [thread overview]
Message-ID: <5e17e6d2-efe0-2781-00a5-6c5b9f185f19@redhat.com> (raw)
In-Reply-To: <20201124124557.140048-1-maxime.coquelin@redhat.com>
On 2020/11/24 下午8:45, Maxime Coquelin wrote:
> 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(-)
Hi Maxime:
To be safe, it's better to check whether or not the kernel support
batching flags.
This could be done by using VHOST_GET_BACKEND_FEATURES to test whether
VHOST_BACKEND_F_IOTLB_BATCH is there.
Thanks
>
> 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,
> };
next prev parent reply other threads:[~2020-11-25 2:18 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-24 12:45 Maxime Coquelin
2020-11-25 2:18 ` Jason Wang [this message]
-- strict thread matches above, loose matches on Subject: below --
2020-11-24 12:45 Maxime Coquelin
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