On 10/22/2015 10:26 AM, Jianfeng wrote:
> -----Original Message-----
> From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Huawei Xie
> Sent: Tuesday, October 20, 2015 11:30 PM
> To: dev at dpdk.org
> Subject: [dpdk-dev] [PATCH v3 6/7] virtio: simple tx routine
>
> Changes in v3:
> - Remove return at the end of void function
> - Remove always_inline attribute for virtio_xmit_cleanup
>
> bulk free of mbufs when clean used ring.
> shift operation of idx could be saved if vq_free_cnt means free slots rather
> than free descriptors.
>
> TODO: rearrange vq data structure, pack the stats var together so that we
> could use one vec instruction to update all of them.
>
> Signed-off-by: Huawei Xie <huawei.xie at intel.com>
> ---
> drivers/net/virtio/virtio_ethdev.h | 3 ++
> drivers/net/virtio/virtio_rxtx_simple.c | 93
> +++++++++++++++++++++++++++++++++
> 2 files changed, 96 insertions(+)
>
> diff --git a/drivers/net/virtio/virtio_ethdev.h
> b/drivers/net/virtio/virtio_ethdev.h
> index d7797ab..ae2d47d 100644
> --- a/drivers/net/virtio/virtio_ethdev.h
> +++ b/drivers/net/virtio/virtio_ethdev.h
> @@ -111,6 +111,9 @@ uint16_t virtio_xmit_pkts(void *tx_queue, struct
> rte_mbuf **tx_pkts, uint16_t virtio_recv_pkts_vec(void *rx_queue, struct
> rte_mbuf **rx_pkts,
> uint16_t nb_pkts);
>
> +uint16_t virtio_xmit_pkts_simple(void *tx_queue, struct rte_mbuf
> **tx_pkts,
> + uint16_t nb_pkts);
> +
> /*
> * The VIRTIO_NET_F_GUEST_TSO[46] features permit the host to send us
> * frames larger than 1514 bytes. We do not yet support software LRO diff --
> git a/drivers/net/virtio/virtio_rxtx_simple.c
> b/drivers/net/virtio/virtio_rxtx_simple.c
> index ef17562..a53d462 100644
> --- a/drivers/net/virtio/virtio_rxtx_simple.c
> +++ b/drivers/net/virtio/virtio_rxtx_simple.c
> @@ -288,6 +288,99 @@ virtio_recv_pkts_vec(void *rx_queue, struct
> rte_mbuf **rx_pkts,
> return nb_pkts_received;
> }
>
> +#define VIRTIO_TX_FREE_THRESH 32
> +#define VIRTIO_TX_MAX_FREE_BUF_SZ 32
> +#define VIRTIO_TX_FREE_NR 32
> +/* TODO: vq->tx_free_cnt could mean num of free slots so we could avoid
> +shift */ static inline void virtio_xmit_cleanup(struct virtqueue *vq) {
> + uint16_t i, desc_idx;
> + int nb_free = 0;
> + struct rte_mbuf *m, *free[VIRTIO_TX_MAX_FREE_BUF_SZ];
> +
> + desc_idx = (uint16_t)(vq->vq_used_cons_idx &
> + ((vq->vq_nentries >> 1) - 1));
> + free[0] = (struct rte_mbuf *)vq->vq_descx[desc_idx++].cookie;
> + nb_free = 1;
> +
> + for (i = 1; i < VIRTIO_TX_FREE_NR; i++) {
> + m = (struct rte_mbuf *)vq->vq_descx[desc_idx++].cookie;
> + if (likely(m->pool == free[0]->pool))
> + free[nb_free++] = m;
> + else {
> + rte_mempool_put_bulk(free[0]->pool, (void **)free,
> + nb_free);
> + free[0] = m;
> + nb_free = 1;
> + }
> + }
> +
> + rte_mempool_put_bulk(free[0]->pool, (void **)free, nb_free);
> + vq->vq_used_cons_idx += VIRTIO_TX_FREE_NR;
> + vq->vq_free_cnt += (VIRTIO_TX_FREE_NR << 1); }
> +
> +uint16_t
> +virtio_xmit_pkts_simple(void *tx_queue, struct rte_mbuf **tx_pkts,
> + uint16_t nb_pkts)
> +{
> + struct virtqueue *txvq = tx_queue;
> + uint16_t nb_used;
> + uint16_t desc_idx;
> + struct vring_desc *start_dp;
> + uint16_t nb_tail, nb_commit;
> + int i;
> + uint16_t desc_idx_max = (txvq->vq_nentries >> 1) - 1;
> +
> + nb_used = VIRTQUEUE_NUSED(txvq);
> + rte_compiler_barrier();
> +
> + nb_commit = nb_pkts = RTE_MIN((txvq->vq_free_cnt >> 1),
> nb_pkts);
Here if nb_commit is zero, how about return 0 immediately?
> + desc_idx = (uint16_t) (txvq->vq_avail_idx & desc_idx_max);
> + start_dp = txvq->vq_ring.desc;
> + nb_tail = (uint16_t) (desc_idx_max + 1 - desc_idx);
> +
> + if (nb_used >= VIRTIO_TX_FREE_THRESH)
> + virtio_xmit_cleanup(tx_queue);
If this cleanup should be put before vq_free_cnt is referenced? It's because it
may free some descs to vq_free_cnt.
> +
> + if (nb_commit >= nb_tail) {
> + for (i = 0; i < nb_tail; i++)
> + txvq->vq_descx[desc_idx + i].cookie = tx_pkts[i];
> + for (i = 0; i < nb_tail; i++) {
> + start_dp[desc_idx].addr =
> + RTE_MBUF_DATA_DMA_ADDR(*tx_pkts);
> + start_dp[desc_idx].len = (*tx_pkts)->pkt_len;
> + tx_pkts++;
> + desc_idx++;
> + }
> + nb_commit -= nb_tail;
> + desc_idx = 0;
> + }
> + for (i = 0; i < nb_commit; i++)
> + txvq->vq_descx[desc_idx + i].cookie = tx_pkts[i];
> + for (i = 0; i < nb_commit; i++) {
> + start_dp[desc_idx].addr =
> RTE_MBUF_DATA_DMA_ADDR(*tx_pkts);
> + start_dp[desc_idx].len = (*tx_pkts)->pkt_len;
> + tx_pkts++;
> + desc_idx++;
> + }
> +
> + rte_compiler_barrier();
> +
> + txvq->vq_free_cnt -= (uint16_t)(nb_pkts << 1);
> + txvq->vq_avail_idx += nb_pkts;
> + txvq->vq_ring.avail->idx = txvq->vq_avail_idx;
> + txvq->packets += nb_pkts;
> +
> + if (likely(nb_pkts)) {
> + if (unlikely(virtqueue_kick_prepare(txvq)))
> + virtqueue_notify(txvq);
> + }
> +
> + return nb_pkts;
> +}
> +
> int __attribute__((cold))
> virtio_rxq_vec_setup(struct virtqueue *rxq) {
> --
> 1.8.1.4
