Re: [dpdk-dev] [PATCH v2 04/15] vhost: simplify async IO vectors iterators

["Xia, Chenbo" <chenbo.xia@intel.com>]

> -----Original Message-----
> From: Maxime Coquelin <maxime.coquelin@redhat.com>
> Sent: Wednesday, October 27, 2021 12:29 AM
> To: dev@dpdk.org; Xia, Chenbo <chenbo.xia@intel.com>; Hu, Jiayu
> <jiayu.hu@intel.com>; Wang, YuanX <yuanx.wang@intel.com>; Ma, WenwuX
> <wenwux.ma@intel.com>; Richardson, Bruce <bruce.richardson@intel.com>;
> Mcnamara, John <john.mcnamara@intel.com>
> Cc: Maxime Coquelin <maxime.coquelin@redhat.com>
> Subject: [PATCH v2 04/15] vhost: simplify async IO vectors iterators
> 
> This patch splits the iterator arrays in two, one for
> source and one for destination. The goal is make the code
> easier to understand.
> 
> Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
> ---
>  lib/vhost/vhost.h      |  5 +++--
>  lib/vhost/virtio_net.c | 24 ++++++++++++------------
>  2 files changed, 15 insertions(+), 14 deletions(-)
> 
> diff --git a/lib/vhost/vhost.h b/lib/vhost/vhost.h
> index 686f468eff..132c1b070e 100644
> --- a/lib/vhost/vhost.h
> +++ b/lib/vhost/vhost.h
> @@ -48,7 +48,7 @@
> 
>  #define MAX_PKT_BURST 32
> 
> -#define VHOST_MAX_ASYNC_IT (MAX_PKT_BURST * 2)
> +#define VHOST_MAX_ASYNC_IT (MAX_PKT_BURST)
>  #define VHOST_MAX_ASYNC_VEC (BUF_VECTOR_MAX * 2)
> 
>  #define PACKED_DESC_ENQUEUE_USED_FLAG(w)	\
> @@ -132,7 +132,8 @@ struct vhost_async {
>  	/* operation callbacks for DMA */
>  	struct rte_vhost_async_channel_ops ops;
> 
> -	struct rte_vhost_iov_iter it_pool[VHOST_MAX_ASYNC_IT];
> +	struct rte_vhost_iov_iter src_iov_iter[VHOST_MAX_ASYNC_IT];
> +	struct rte_vhost_iov_iter dst_iov_iter[VHOST_MAX_ASYNC_IT];
>  	struct iovec src_iovec[VHOST_MAX_ASYNC_VEC];
>  	struct iovec dst_iovec[VHOST_MAX_ASYNC_VEC];
> 
> diff --git a/lib/vhost/virtio_net.c b/lib/vhost/virtio_net.c
> index 2a243701c0..f0d923704a 100644
> --- a/lib/vhost/virtio_net.c
> +++ b/lib/vhost/virtio_net.c
> @@ -1511,7 +1511,8 @@ virtio_dev_rx_async_submit_split(struct virtio_net *dev,
>  	uint16_t avail_head;
> 
>  	struct vhost_async *async = vq->async;
> -	struct rte_vhost_iov_iter *it_pool = async->it_pool;
> +	struct rte_vhost_iov_iter *src_iter = async->src_iov_iter;
> +	struct rte_vhost_iov_iter *dst_iter = async->dst_iov_iter;
>  	struct rte_vhost_async_desc tdes[MAX_PKT_BURST];
>  	struct iovec *src_iovec = async->src_iovec;
>  	struct iovec *dst_iovec = async->dst_iovec;
> @@ -1547,20 +1548,19 @@ virtio_dev_rx_async_submit_split(struct virtio_net
> *dev,
> 
>  		if (async_mbuf_to_desc(dev, vq, pkts[pkt_idx], buf_vec, nr_vec,
> num_buffers,
>  				&src_iovec[iovec_idx], &dst_iovec[iovec_idx],
> -				&it_pool[it_idx], &it_pool[it_idx + 1]) < 0) {
> +				&src_iter[it_idx], &dst_iter[it_idx]) < 0) {
>  			vq->shadow_used_idx -= num_buffers;
>  			break;
>  		}
> 
> -		async_fill_desc(&tdes[pkt_burst_idx++], &it_pool[it_idx],
> -				&it_pool[it_idx + 1]);
> +		async_fill_desc(&tdes[pkt_burst_idx++], &src_iter[it_idx],
> &dst_iter[it_idx]);
> 
>  		slot_idx = (async->pkts_idx + pkt_idx) & (vq->size - 1);
>  		pkts_info[slot_idx].descs = num_buffers;
>  		pkts_info[slot_idx].mbuf = pkts[pkt_idx];
> 
> -		iovec_idx += it_pool[it_idx].nr_segs;
> -		it_idx += 2;
> +		iovec_idx += src_iter[it_idx].nr_segs;
> +		it_idx++;
> 
>  		vq->last_avail_idx += num_buffers;
> 
> @@ -1829,7 +1829,8 @@ virtio_dev_rx_async_submit_packed(struct virtio_net *dev,
>  	uint16_t num_descs;
> 
>  	struct vhost_async *async = vq->async;
> -	struct rte_vhost_iov_iter *it_pool = async->it_pool;
> +	struct rte_vhost_iov_iter *src_iter = async->src_iov_iter;
> +	struct rte_vhost_iov_iter *dst_iter = async->dst_iov_iter;
>  	struct rte_vhost_async_desc tdes[MAX_PKT_BURST];
>  	struct iovec *src_iovec = async->src_iovec;
>  	struct iovec *dst_iovec = async->dst_iovec;
> @@ -1846,18 +1847,17 @@ virtio_dev_rx_async_submit_packed(struct virtio_net
> *dev,
>  		if (unlikely(virtio_dev_rx_async_packed(dev, vq, pkts[pkt_idx],
>  						&num_descs, &num_buffers,
>  						&src_iovec[iovec_idx],
> &dst_iovec[iovec_idx],
> -						&it_pool[it_idx], &it_pool[it_idx + 1]) <
> 0))
> +						&src_iter[it_idx], &dst_iter[it_idx]) < 0))
>  			break;
> 
>  		slot_idx = (async->pkts_idx + pkt_idx) % vq->size;
> 
> -		async_fill_desc(&tdes[pkt_burst_idx++], &it_pool[it_idx],
> -				&it_pool[it_idx + 1]);
> +		async_fill_desc(&tdes[pkt_burst_idx++], &src_iter[it_idx],
> &dst_iter[it_idx]);
>  		pkts_info[slot_idx].descs = num_descs;
>  		pkts_info[slot_idx].nr_buffers = num_buffers;
>  		pkts_info[slot_idx].mbuf = pkts[pkt_idx];
> -		iovec_idx += it_pool[it_idx].nr_segs;
> -		it_idx += 2;
> +		iovec_idx += src_iter[it_idx].nr_segs;
> +		it_idx++;
> 
>  		pkt_idx++;
>  		remained--;
> --
> 2.31.1

Reviewed-by: Chenbo Xia <chenbo.xia@intel.com>