Re: [Qemu-devel] [ RFC Patch v4 3/3] virtio-net rsc: support coalescing ipv6 tcp traffic

[Jason Wang <jasowang@redhat.com>]

On 04/08/2016 03:06 PM, Wei Xu wrote:
>
>
> On 2016年04月05日 10:50, Jason Wang wrote:
>>
>> On 04/04/2016 03:25 AM, wexu@redhat.com wrote:
>>> From: Wei Xu <wexu@redhat.com>
>>>
>>> Most things like ipv4 except there is a significant difference
>>> between ipv4
>>> and ipv6, the fragment lenght in ipv4 header includes itself, while
>>> it's not
>> typo
> Thanks.
>>
>>> included for ipv6, thus means ipv6 can carry a real '65535' payload.
>>>
>>> Signed-off-by: Wei Xu <wexu@redhat.com>
>>> ---
>>>   hw/net/virtio-net.c | 147
>>> +++++++++++++++++++++++++++++++++++++++++++++++++---
>>>   1 file changed, 141 insertions(+), 6 deletions(-)
>>>
>>> diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
>>> index 81e8e71..2d09352 100644
>>> --- a/hw/net/virtio-net.c
>>> +++ b/hw/net/virtio-net.c
>>> @@ -50,6 +50,10 @@
>>>   /* header lenght value in ip header without option */
>>>   #define VIRTIO_NET_IP4_HEADER_LENGTH 5
>>>   +#define ETH_IP6_HDR_SZ (ETH_HDR_SZ + IP6_HDR_SZ)
>>> +#define VIRTIO_NET_IP6_ADDR_SIZE   32      /* ipv6 saddr + daddr */
>>> +#define VIRTIO_NET_MAX_IP6_PAYLOAD VIRTIO_NET_MAX_TCP_PAYLOAD
>>> +
>>>   /* Purge coalesced packets timer interval */
>>>   #define VIRTIO_NET_RSC_INTERVAL  300000
>>>   @@ -1725,6 +1729,25 @@ static void
>>> virtio_net_rsc_extract_unit4(NetRscChain *chain,
>>>       unit->payload = htons(*unit->ip_plen) - ip_hdrlen -
>>> unit->tcp_hdrlen;
>>>   }
>>>   +static void virtio_net_rsc_extract_unit6(NetRscChain *chain,
>>> +                                         const uint8_t *buf,
>>> NetRscUnit* unit)
>>> +{
>>> +    uint16_t hdr_len;
>>> +    struct ip6_header *ip6;
>>> +
>>> +    hdr_len = ((VirtIONet *)(chain->n))->guest_hdr_len;
>>> +    ip6 = (struct ip6_header *)(buf + hdr_len + sizeof(struct
>>> eth_header));
>>> +    unit->ip = ip6;
>>> +    unit->ip_plen = &(ip6->ip6_ctlun.ip6_un1.ip6_un1_plen);
>>> +    unit->tcp = (struct tcp_header *)(((uint8_t *)unit->ip)\
>>> +                                        + sizeof(struct ip6_header));
>>> +    unit->tcp_hdrlen = (htons(unit->tcp->th_offset_flags) & 0xF000)
>>> >> 10;
>>> +
>>> +    /* There is a difference between payload lenght in ipv4 and v6,
>>> +       ip header is excluded in ipv6 */
>>> +    unit->payload = htons(*unit->ip_plen) - unit->tcp_hdrlen;
>>> +}
>>> +
>>>   static void virtio_net_rsc_ipv4_checksum(struct ip_header *ip)
>>>   {
>>>       uint32_t sum;
>>> @@ -1738,7 +1761,9 @@ static size_t
>>> virtio_net_rsc_drain_seg(NetRscChain *chain, NetRscSeg *seg)
>>>   {
>>>       int ret;
>>>   -    virtio_net_rsc_ipv4_checksum(seg->unit.ip);
>>> +    if ((chain->proto == ETH_P_IP) && seg->is_coalesced) {
>>> +        virtio_net_rsc_ipv4_checksum(seg->unit.ip);
>>> +    }
>> Why not introduce proto specific checksum function for chain?
> Since there are only 2 protocols to be supported, and very limited
> extension for this feature, mst suggest to use direct call in v2 patch
> to make things simple, and i took it.

Have you tried with my suggestion? I think it will actually simplify the
current code (at least several lines of codes).