[dpdk-dev] [PATCH v3 15/21] vhost: packed queue enqueue path
Maxime Coquelin
maxime.coquelin at redhat.com
Fri Apr 6 11:36:03 CEST 2018
On 04/05/2018 12:10 PM, Jens Freimann wrote:
> Implement enqueue of packets to the receive virtqueue.
>
> Set descriptor flag VIRTQ_DESC_F_USED and toggle used wrap counter if
> last descriptor in ring is used. Perform a write memory barrier before
> flags are written to descriptor.
>
> Chained descriptors are not supported with this patch.
>
> Signed-off-by: Jens Freimann <jfreimann at redhat.com>
> ---
> lib/librte_vhost/virtio_net.c | 129 ++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 129 insertions(+)
>
> diff --git a/lib/librte_vhost/virtio_net.c b/lib/librte_vhost/virtio_net.c
> index 7eea1da04..578e5612e 100644
> --- a/lib/librte_vhost/virtio_net.c
> +++ b/lib/librte_vhost/virtio_net.c
> @@ -695,6 +695,135 @@ virtio_dev_merge_rx(struct virtio_net *dev, uint16_t queue_id,
> return pkt_idx;
> }
>
> +static inline uint32_t __attribute__((always_inline))
> +vhost_enqueue_burst_packed(struct virtio_net *dev, uint16_t queue_id,
> + struct rte_mbuf **pkts, uint32_t count)
> +{
> + struct vhost_virtqueue *vq;
> + struct vring_desc_packed *descs;
> + uint16_t idx;
> + uint16_t mask;
> + uint16_t i;
> +
> + vq = dev->virtqueue[queue_id];
> +
> + rte_spinlock_lock(&vq->access_lock);
> +
> + if (unlikely(vq->enabled == 0)) {
> + i = 0;
> + goto out_access_unlock;
> + }
> +
> + if (dev->features & (1ULL << VIRTIO_F_IOMMU_PLATFORM))
> + vhost_user_iotlb_rd_lock(vq);
> +
> + descs = vq->desc_packed;
> + mask = vq->size - 1;
> +
> + for (i = 0; i < count; i++) {
> + uint32_t desc_avail, desc_offset;
> + uint32_t mbuf_avail, mbuf_offset;
> + uint32_t cpy_len;
> + struct vring_desc_packed *desc;
> + uint64_t desc_addr;
> + struct virtio_net_hdr_mrg_rxbuf *hdr;
> + struct rte_mbuf *m = pkts[i];
> +
> + /* XXX: there is an assumption that no desc will be chained */
Is this assumption still true?
If not what are the plan to fix this?
> + idx = vq->last_used_idx & mask;
> + desc = &descs[idx];
> +
> + if (!desc_is_avail(vq, desc))
IIUC, it means the ring is full.
I think this is an unlikely case, so maybe better to use the unlikely
macro here.
> + break;
> + rte_smp_rmb();
> +
> + desc_addr = vhost_iova_to_vva(dev, vq, desc->addr,
> + sizeof(*desc), VHOST_ACCESS_RW);
> + /*
> + * Checking of 'desc_addr' placed outside of 'unlikely' macro
> + * to avoid performance issue with some versions of gcc (4.8.4
> + * and 5.3.0) which otherwise stores offset on the stack instead
> + * of in a register.
> + */
> + if (unlikely(desc->len < dev->vhost_hlen) || !desc_addr)
> + break;
> +
> + hdr = (struct virtio_net_hdr_mrg_rxbuf *)(uintptr_t)desc_addr;
> + virtio_enqueue_offload(m, &hdr->hdr);
> + vhost_log_write(dev, desc->addr, dev->vhost_hlen);
> + PRINT_PACKET(dev, (uintptr_t)desc_addr, dev->vhost_hlen, 0);
> +
> + desc_offset = dev->vhost_hlen;
> + desc_avail = desc->len - dev->vhost_hlen;
> +
> + mbuf_avail = rte_pktmbuf_data_len(m);
> + mbuf_offset = 0;
> + while (mbuf_avail != 0 || m->next != NULL) {
> + /* done with current mbuf, fetch next */
> + if (mbuf_avail == 0) {
> + m = m->next;
> +
> + mbuf_offset = 0;
> + mbuf_avail = rte_pktmbuf_data_len(m);
> + }
> +
> + /* done with current desc buf, fetch next */
> + if (desc_avail == 0) {
> + if ((desc->flags & VRING_DESC_F_NEXT) == 0) {
> + /* Room in vring buffer is not enough */
> + goto out;
> + }
> +
> + idx = (idx+1) & (vq->size - 1);
> + desc = &descs[idx];
> + if (unlikely(!desc_is_avail(vq, desc)))
> + goto out ;
> +
> + desc_addr = vhost_iova_to_vva(dev, vq, desc->addr,
> + sizeof(*desc),
> + VHOST_ACCESS_RW);
> + if (unlikely(!desc_addr))
> + goto out;
> +
> + desc_offset = 0;
> + desc_avail = desc->len;
> + }
> +
> + cpy_len = RTE_MIN(desc_avail, mbuf_avail);
> + rte_memcpy((void *)((uintptr_t)(desc_addr + desc_offset)),
> + rte_pktmbuf_mtod_offset(m, void *, mbuf_offset),
> + cpy_len);
> + vhost_log_write(dev, desc->addr + desc_offset, cpy_len);
> + PRINT_PACKET(dev, (uintptr_t)(desc_addr + desc_offset),
> + cpy_len, 0);
> +
> + mbuf_avail -= cpy_len;
> + mbuf_offset += cpy_len;
> + desc_avail -= cpy_len;
> + desc_offset += cpy_len;
> + }
> +
> + descs[idx].len = pkts[i]->pkt_len + dev->vhost_hlen;
> + rte_smp_wmb();
> + set_desc_used(vq, desc);
> +
> + vq->last_used_idx++;
> + if ((vq->last_used_idx & (vq->size - 1)) == 0)
> + toggle_wrap_counter(vq);
> + }
> +
> +out:
> + if (dev->features & (1ULL << VIRTIO_F_IOMMU_PLATFORM))
> + vhost_user_iotlb_rd_unlock(vq);
> +
> +out_access_unlock:
> + rte_spinlock_unlock(&vq->access_lock);
> +
> + count = i;
> +
> + return count;
> +}
> +
> uint16_t
> rte_vhost_enqueue_burst(int vid, uint16_t queue_id,
> struct rte_mbuf **pkts, uint16_t count)
>
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