Re: [Qemu-devel] [ RFC Patch v6 3/3] virtio-net rsc: add 2 new rsc information fields to 'virtio_net_hdr'

[Jason Wang <jasowang@redhat.com>]

On 2016年05月29日 00:37, wexu@redhat.com wrote:
> From: Wei Xu <wexu@redhat.com>
>
> Field 'coalesced' is to indicate how many packets are coalesced and field
> 'dup_ack' is how many duplicate acks are merged, guest driver can use these
> information to notify what's the exact scene of original traffic over the
> networks.
>
> Signed-off-by: Wei Xu <wexu@redhat.com>
> ---
>   hw/net/virtio-net.c                         | 8 ++++++++
>   include/standard-headers/linux/virtio_net.h | 2 ++
>   2 files changed, 10 insertions(+)
>
> diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
> index cc8cbe4..20f552a 100644
> --- a/hw/net/virtio-net.c
> +++ b/hw/net/virtio-net.c
> @@ -1768,6 +1768,10 @@ static size_t virtio_net_rsc_drain_seg(NetRscChain *chain, NetRscSeg *seg)
>       if ((chain->proto == ETH_P_IP) && seg->is_coalesced) {
>           virtio_net_rsc_ipv4_checksum(h, seg->unit.ip);
>       }
> +    h->coalesced = seg->packets;
> +    h->dup_ack = seg->dup_ack;
> +    h->gso_type = chain->gso_type;
> +    h->gso_size = chain->max_payload;
>       ret = virtio_net_do_receive(seg->nc, seg->buf, seg->size);
>       QTAILQ_REMOVE(&chain->buffers, seg, next);
>       g_free(seg->buf);
> @@ -2302,9 +2306,13 @@ static ssize_t virtio_net_receive(NetClientState *nc,
>                                     const uint8_t *buf, size_t size)
>   {
>       VirtIONet *n;
> +    struct virtio_net_hdr *h;
>   
>       n = qemu_get_nic_opaque(nc);
>       if (n->host_features & (1ULL << VIRTIO_NET_F_GUEST_RSC)) {
> +        h = (struct virtio_net_hdr *)buf;
> +        h->coalesced = 0;
> +        h->dup_ack = 0;
>           return virtio_net_rsc_receive(nc, buf, size);
>       } else {
>           return virtio_net_do_receive(nc, buf, size);
> diff --git a/include/standard-headers/linux/virtio_net.h b/include/standard-headers/linux/virtio_net.h
> index 5b95762..c837417 100644
> --- a/include/standard-headers/linux/virtio_net.h
> +++ b/include/standard-headers/linux/virtio_net.h
> @@ -114,6 +114,8 @@ struct virtio_net_hdr {
>   	__virtio16 gso_size;		/* Bytes to append to hdr_len per frame */
>   	__virtio16 csum_start;	/* Position to start checksumming from */
>   	__virtio16 csum_offset;	/* Offset after that to place checksum */
> +    __virtio16 coalesced;   /* packets coalesced by host */

Can we just reuse gso_segs for this?

> +    __virtio16 dup_ack;     /* duplicate ack count */
>   };
>   
>   /* This is the version of the header to use when the MRG_RXBUF