Re: [dpdk-dev] [PATCH v9 7/9] net/virtio: add vectorized packed ring Tx path

[Maxime Coquelin <maxime.coquelin@redhat.com>]

On 4/24/20 11:24 AM, Marvin Liu wrote:
> Optimize packed ring Tx path alike Rx path. Split Tx path into batch and

s/alike/like/ ?

> single Tx functions. Batch function is further optimized by AVX512
> instructions.
> 
> Signed-off-by: Marvin Liu <yong.liu@intel.com>
> 
> diff --git a/drivers/net/virtio/virtio_ethdev.h b/drivers/net/virtio/virtio_ethdev.h
> index 5c112cac7..b7d52d497 100644
> --- a/drivers/net/virtio/virtio_ethdev.h
> +++ b/drivers/net/virtio/virtio_ethdev.h
> @@ -108,6 +108,9 @@ uint16_t virtio_recv_pkts_vec(void *rx_queue, struct rte_mbuf **rx_pkts,
>  uint16_t virtio_recv_pkts_packed_vec(void *rx_queue, struct rte_mbuf **rx_pkts,
>  		uint16_t nb_pkts);
>  
> +uint16_t virtio_xmit_pkts_packed_vec(void *tx_queue, struct rte_mbuf **tx_pkts,
> +		uint16_t nb_pkts);
> +
>  int eth_virtio_dev_init(struct rte_eth_dev *eth_dev);
>  
>  void virtio_interrupt_handler(void *param);
> diff --git a/drivers/net/virtio/virtio_rxtx.c b/drivers/net/virtio/virtio_rxtx.c
> index cf18fe564..f82fe8d64 100644
> --- a/drivers/net/virtio/virtio_rxtx.c
> +++ b/drivers/net/virtio/virtio_rxtx.c
> @@ -2175,3 +2175,11 @@ virtio_recv_pkts_packed_vec(void *rx_queue __rte_unused,
>  {
>  	return 0;
>  }
> +
> +__rte_weak uint16_t
> +virtio_xmit_pkts_packed_vec(void *tx_queue __rte_unused,
> +			    struct rte_mbuf **tx_pkts __rte_unused,
> +			    uint16_t nb_pkts __rte_unused)
> +{
> +	return 0;
> +}
> diff --git a/drivers/net/virtio/virtio_rxtx_packed_avx.c b/drivers/net/virtio/virtio_rxtx_packed_avx.c
> index 8a7b459eb..c023ace4e 100644
> --- a/drivers/net/virtio/virtio_rxtx_packed_avx.c
> +++ b/drivers/net/virtio/virtio_rxtx_packed_avx.c
> @@ -23,6 +23,24 @@
>  #define PACKED_FLAGS_MASK ((0ULL | VRING_PACKED_DESC_F_AVAIL_USED) << \
>  	FLAGS_BITS_OFFSET)
>  
> +/* reference count offset in mbuf rearm data */
> +#define REFCNT_BITS_OFFSET ((offsetof(struct rte_mbuf, refcnt) - \
> +	offsetof(struct rte_mbuf, rearm_data)) * BYTE_SIZE)
> +/* segment number offset in mbuf rearm data */
> +#define SEG_NUM_BITS_OFFSET ((offsetof(struct rte_mbuf, nb_segs) - \
> +	offsetof(struct rte_mbuf, rearm_data)) * BYTE_SIZE)
> +
> +/* default rearm data */
> +#define DEFAULT_REARM_DATA (1ULL << SEG_NUM_BITS_OFFSET | \
> +	1ULL << REFCNT_BITS_OFFSET)
> +
> +/* id bits offset in packed ring desc higher 64bits */
> +#define ID_BITS_OFFSET ((offsetof(struct vring_packed_desc, id) - \
> +	offsetof(struct vring_packed_desc, len)) * BYTE_SIZE)
> +
> +/* net hdr short size mask */
> +#define NET_HDR_MASK 0x3F
> +
>  #define PACKED_BATCH_SIZE (RTE_CACHE_LINE_SIZE / \
>  	sizeof(struct vring_packed_desc))
>  #define PACKED_BATCH_MASK (PACKED_BATCH_SIZE - 1)
> @@ -47,6 +65,48 @@
>  	for (iter = val; iter < num; iter++)
>  #endif
>  
> +static inline void
> +virtio_xmit_cleanup_packed_vec(struct virtqueue *vq)
> +{
> +	struct vring_packed_desc *desc = vq->vq_packed.ring.desc;
> +	struct vq_desc_extra *dxp;
> +	uint16_t used_idx, id, curr_id, free_cnt = 0;
> +	uint16_t size = vq->vq_nentries;
> +	struct rte_mbuf *mbufs[size];
> +	uint16_t nb_mbuf = 0, i;
> +
> +	used_idx = vq->vq_used_cons_idx;
> +
> +	if (!desc_is_used(&desc[used_idx], vq))
> +		return;
> +
> +	id = desc[used_idx].id;
> +
> +	do {
> +		curr_id = used_idx;
> +		dxp = &vq->vq_descx[used_idx];
> +		used_idx += dxp->ndescs;
> +		free_cnt += dxp->ndescs;
> +
> +		if (dxp->cookie != NULL) {
> +			mbufs[nb_mbuf] = dxp->cookie;
> +			dxp->cookie = NULL;
> +			nb_mbuf++;
> +		}
> +
> +		if (used_idx >= size) {
> +			used_idx -= size;
> +			vq->vq_packed.used_wrap_counter ^= 1;
> +		}
> +	} while (curr_id != id);
> +
> +	for (i = 0; i < nb_mbuf; i++)
> +		rte_pktmbuf_free(mbufs[i]);
> +
> +	vq->vq_used_cons_idx = used_idx;
> +	vq->vq_free_cnt += free_cnt;
> +}
> +


I think you can re-use the inlined non-vectorized cleanup function here.
Or use your implementation in non-vectorized path.
BTW, do you know we have to pass the num argument in non-vectorized
case? I'm not sure to remember.

Maxime