On 3/4/2016 10:30 AM, Yuanhan Liu wrote:
> On Thu, Mar 03, 2016 at 05:40:14PM +0000, Xie, Huawei wrote:
>> On 2/18/2016 9:48 PM, Yuanhan Liu wrote:
>>> The current rte_vhost_dequeue_burst() implementation is a bit messy
>> [...]
>>> +
>>> uint16_t
>>> rte_vhost_dequeue_burst(struct virtio_net *dev, uint16_t queue_id,
>>> struct rte_mempool *mbuf_pool, struct rte_mbuf **pkts, uint16_t count)
>>> {
>>> - struct rte_mbuf *m, *prev;
>>> struct vhost_virtqueue *vq;
>>> - struct vring_desc *desc;
>>> - uint64_t vb_addr = 0;
>>> - uint64_t vb_net_hdr_addr = 0;
>>> - uint32_t head[MAX_PKT_BURST];
>>> + uint32_t desc_indexes[MAX_PKT_BURST];
>> indices
> http://dictionary.reference.com/browse/index
>
> index
> noun, plural indexes, indices
ok, i see both two are used.
>>
>>> uint32_t used_idx;
>>> uint32_t i;
>>> - uint16_t free_entries, entry_success = 0;
>>> + uint16_t free_entries;
>>> uint16_t avail_idx;
>>> - struct virtio_net_hdr *hdr = NULL;
>>> + struct rte_mbuf *m;
>>>
>>> if (unlikely(!is_valid_virt_queue_idx(queue_id, 1, dev->virt_qp_nb))) {
>>> RTE_LOG(ERR, VHOST_DATA,
>>> @@ -730,197 +813,49 @@ rte_vhost_dequeue_burst(struct virtio_net *dev,
>>> uint16_t queue_id,
>>> return 0;
>>>
>>> - if (entry_success < (free_entries - 1)) {
>>> - /* Prefetch descriptor index. */
>>> - rte_prefetch0(&vq->desc[head[entry_success+1]]);
>>> - rte_prefetch0(&vq->used->ring[(used_idx + 1) &
>>> (vq->size - 1)]);
>>> - }
>> Why is this prefetch silently dropped in the patch?
> Oops, good catching. Will fix it. Thanks.
>
>
>>> break;
>>> + pkts[i] = m;
>>>
>>> - m->nb_segs = seg_num;
>>> - if ((hdr->flags != 0) || (hdr->gso_type !=
>>> VIRTIO_NET_HDR_GSO_NONE))
>>> - vhost_dequeue_offload(hdr, m);
>>> -
>>> - pkts[entry_success] = m;
>>> - vq->last_used_idx++;
>>> - entry_success++;
>>> + used_idx = vq->last_used_idx++ & (vq->size - 1);
>>> + vq->used->ring[used_idx].id = desc_indexes[i];
>>> + vq->used->ring[used_idx].len = 0;
>> What is the correct value for ring[used_idx].len, the packet length or 0?
> Good question. I didn't notice that before. Sounds buggy to me. However,
> that's from the old code. Will check it.
Yes, i knew it is in old code also. Thanks.
> --yliu
>
