On Tue, Oct 11, 2016 at 09:45:27AM +0200, Maxime Coquelin wrote:
> @@ -684,12 +699,12 @@ copy_desc_to_mbuf(struct virtio_net *dev, struct
> vring_desc *descs,
> struct rte_mempool *mbuf_pool)
> {
> struct vring_desc *desc;
> - uint64_t desc_addr;
> + uint64_t desc_addr = 0;
> uint32_t desc_avail, desc_offset;
> uint32_t mbuf_avail, mbuf_offset;
> uint32_t cpy_len;
> struct rte_mbuf *cur = m, *prev = m;
> - struct virtio_net_hdr *hdr;
> + struct virtio_net_hdr *hdr = NULL;
> /* A counter to avoid desc dead loop chain */
> uint32_t nr_desc = 1;
>
> @@ -698,12 +713,14 @@ copy_desc_to_mbuf(struct virtio_net *dev, struct
> vring_desc *descs,
> (desc->flags & VRING_DESC_F_INDIRECT))
> return -1;
>
> - desc_addr = gpa_to_vva(dev, desc->addr);
> - if (unlikely(!desc_addr))
> - return -1;
> + if (virtio_net_with_host_offload(dev)) {
> + desc_addr = gpa_to_vva(dev, desc->addr);
> + if (unlikely(!desc_addr))
> + return -1;
>
> - hdr = (struct virtio_net_hdr *)((uintptr_t)desc_addr);
> - rte_prefetch0(hdr);
> + hdr = (struct virtio_net_hdr *)((uintptr_t)desc_addr);
> + rte_prefetch0(hdr);
> + }
>
> /*
> * A virtio driver normally uses at least 2 desc buffers
> @@ -720,18 +737,24 @@ copy_desc_to_mbuf(struct virtio_net *dev, struct
> vring_desc *descs,
> if (unlikely(!desc_addr))
> return -1;
>
> - rte_prefetch0((void *)(uintptr_t)desc_addr);
> -
> desc_offset = 0;
> desc_avail = desc->len;
> nr_desc += 1;
> -
> - PRINT_PACKET(dev, (uintptr_t)desc_addr, desc->len, 0);
> } else {
> + if (!desc_addr) {
> + desc_addr = gpa_to_vva(dev, desc->addr);
> + if (unlikely(!desc_addr))
> + return -1;
> + }
> +
I think this piece of code make things a bit complex. I think what you
want to achieve is, besides saving hdr prefetch, to save one call to
gpa_to_vva() for the non-ANY_LAYOUT case. Does that matter too much?
How about just saving the hdr prefetch?
if (virtio_net_with_host_offload(dev)) {
hdr = (struct virtio_net_hdr *)((uintptr_t)desc_addr);
rte_prefetch0(hdr);
}
--yliu
> desc_avail = desc->len - dev->vhost_hlen;
> desc_offset = dev->vhost_hlen;
> }
>
> + rte_prefetch0((void *)(uintptr_t)(desc_addr + desc_offset));
> +
> + PRINT_PACKET(dev, (uintptr_t)(desc_addr + desc_offset), desc_avail, 0);
> +
> mbuf_offset = 0;
> mbuf_avail = m->buf_len - RTE_PKTMBUF_HEADROOM;
> while (1) {
> @@ -795,7 +818,7 @@ copy_desc_to_mbuf(struct virtio_net *dev, struct
> vring_desc *descs,
> prev->data_len = mbuf_offset;
> m->pkt_len += mbuf_offset;
>
> - if (hdr->flags != 0 || hdr->gso_type != VIRTIO_NET_HDR_GSO_NONE)
> + if (virtio_net_with_host_offload(dev))
> vhost_dequeue_offload(hdr, m);
>
> return 0;
> --
> 2.7.4
