> -----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 5/7] virtio: virtio vec rx
>
> With fixed avail ring, we don't need to get desc idx from avail ring.
> virtio driver only has to deal with desc ring.
> This patch uses vector instruction to accelerate processing desc ring.
>
> Signed-off-by: Huawei Xie <huawei.xie at intel.com>
> ---
> drivers/net/virtio/virtio_ethdev.h | 2 +
> drivers/net/virtio/virtio_rxtx.c | 3 +
> drivers/net/virtio/virtio_rxtx.h | 2 +
> drivers/net/virtio/virtio_rxtx_simple.c | 224
> ++++++++++++++++++++++++++++++++
> drivers/net/virtio/virtqueue.h | 1 +
> 5 files changed, 232 insertions(+)
>
> diff --git a/drivers/net/virtio/virtio_ethdev.h
> b/drivers/net/virtio/virtio_ethdev.h
> index 9026d42..d7797ab 100644
> --- a/drivers/net/virtio/virtio_ethdev.h
> +++ b/drivers/net/virtio/virtio_ethdev.h
> @@ -108,6 +108,8 @@ uint16_t virtio_recv_mergeable_pkts(void *rx_queue,
> struct rte_mbuf **rx_pkts,
> uint16_t virtio_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts,
> uint16_t nb_pkts);
>
> +uint16_t virtio_recv_pkts_vec(void *rx_queue, struct rte_mbuf **rx_pkts,
> + uint16_t nb_pkts);
>
> /*
> * The VIRTIO_NET_F_GUEST_TSO[46] features permit the host to send us
> diff --git a/drivers/net/virtio/virtio_rxtx.c
> b/drivers/net/virtio/virtio_rxtx.c
> index 5162ce6..947fc46 100644
> --- a/drivers/net/virtio/virtio_rxtx.c
> +++ b/drivers/net/virtio/virtio_rxtx.c
> @@ -432,6 +432,9 @@ virtio_dev_rx_queue_setup(struct rte_eth_dev *dev,
> vq->mpool = mp;
>
> dev->data->rx_queues[queue_idx] = vq;
> +
> + virtio_rxq_vec_setup(vq);
> +
> return 0;
> }
>
> diff --git a/drivers/net/virtio/virtio_rxtx.h
> b/drivers/net/virtio/virtio_rxtx.h
> index 7d2d8fe..831e492 100644
> --- a/drivers/net/virtio/virtio_rxtx.h
> +++ b/drivers/net/virtio/virtio_rxtx.h
> @@ -33,5 +33,7 @@
>
> #define RTE_PMD_VIRTIO_RX_MAX_BURST 64
>
> +int virtio_rxq_vec_setup(struct virtqueue *rxq);
> +
> int virtqueue_enqueue_recv_refill_simple(struct virtqueue *vq,
> struct rte_mbuf *m);
> diff --git a/drivers/net/virtio/virtio_rxtx_simple.c
> b/drivers/net/virtio/virtio_rxtx_simple.c
> index cac5b9f..ef17562 100644
> --- a/drivers/net/virtio/virtio_rxtx_simple.c
> +++ b/drivers/net/virtio/virtio_rxtx_simple.c
> @@ -58,6 +58,10 @@
> #include "virtqueue.h"
> #include "virtio_rxtx.h"
>
> +#define RTE_VIRTIO_VPMD_RX_BURST 32
> +#define RTE_VIRTIO_DESC_PER_LOOP 8
> +#define RTE_VIRTIO_VPMD_RX_REARM_THRESH
> RTE_VIRTIO_VPMD_RX_BURST
> +
> int __attribute__((cold))
> virtqueue_enqueue_recv_refill_simple(struct virtqueue *vq,
> struct rte_mbuf *cookie)
> @@ -82,3 +86,223 @@ virtqueue_enqueue_recv_refill_simple(struct
> virtqueue *vq,
>
> return 0;
> }
> +
> +static inline void
> +virtio_rxq_rearm_vec(struct virtqueue *rxvq)
> +{
> + int i;
> + uint16_t desc_idx;
> + struct rte_mbuf **sw_ring;
> + struct vring_desc *start_dp;
> + int ret;
> +
> + desc_idx = rxvq->vq_avail_idx & (rxvq->vq_nentries - 1);
> + sw_ring = &rxvq->sw_ring[desc_idx];
> + start_dp = &rxvq->vq_ring.desc[desc_idx];
> +
> + ret = rte_mempool_get_bulk(rxvq->mpool, (void **)sw_ring,
> + RTE_VIRTIO_VPMD_RX_REARM_THRESH);
> + if (unlikely(ret)) {
> + rte_eth_devices[rxvq->port_id].data->rx_mbuf_alloc_failed +=
> + RTE_VIRTIO_VPMD_RX_REARM_THRESH;
> + return;
> + }
> +
> + for (i = 0; i < RTE_VIRTIO_VPMD_RX_REARM_THRESH; i++) {
> + uintptr_t p;
> +
> + p = (uintptr_t)&sw_ring[i]->rearm_data;
> + *(uint64_t *)p = rxvq->mbuf_initializer;
> +
> + start_dp[i].addr =
> + (uint64_t)((uintptr_t)sw_ring[i]->buf_physaddr +
> + RTE_PKTMBUF_HEADROOM - sizeof(struct virtio_net_hdr));
> + start_dp[i].len = sw_ring[i]->buf_len -
> + RTE_PKTMBUF_HEADROOM + sizeof(struct virtio_net_hdr);
> + }
> +
> + rxvq->vq_avail_idx += RTE_VIRTIO_VPMD_RX_REARM_THRESH;
> + rxvq->vq_free_cnt -= RTE_VIRTIO_VPMD_RX_REARM_THRESH;
> + vq_update_avail_idx(rxvq);
> +}
> +
> +/* virtio vPMD receive routine, only accept(nb_pkts >=
> RTE_VIRTIO_DESC_PER_LOOP)
> + *
> + * This routine is for non-mergable RX, one desc for each guest buffer.
> + * This routine is based on the RX ring layout optimization. Each entry in
> the
> + * avail ring points to the desc with the same index in the desc ring and
> this
> + * will never be changed in the driver.
> + *
> + * - nb_pkts < RTE_VIRTIO_DESC_PER_LOOP, just return no packet
> + */
> +uint16_t
> +virtio_recv_pkts_vec(void *rx_queue, struct rte_mbuf **rx_pkts,
> + uint16_t nb_pkts)
> +{
> + struct virtqueue *rxvq = rx_queue;
> + uint16_t nb_used;
> + uint16_t desc_idx;
> + struct vring_used_elem *rused;
> + struct rte_mbuf **sw_ring;
> + struct rte_mbuf **sw_ring_end;
> + uint16_t nb_pkts_received;
> + __m128i shuf_msk1, shuf_msk2, len_adjust;
> +
> + shuf_msk1 = _mm_set_epi8(
> + 0xFF, 0xFF, 0xFF, 0xFF,
> + 0xFF, 0xFF, /* vlan tci */
> + 5, 4, /* dat len */
> + 0xFF, 0xFF, 5, 4, /* pkt len */
> + 0xFF, 0xFF, 0xFF, 0xFF /* packet type */
> +
> + );
> +
> + shuf_msk2 = _mm_set_epi8(
> + 0xFF, 0xFF, 0xFF, 0xFF,
> + 0xFF, 0xFF, /* vlan tci */
> + 13, 12, /* dat len */
> + 0xFF, 0xFF, 13, 12, /* pkt len */
> + 0xFF, 0xFF, 0xFF, 0xFF /* packet type */
> + );
> +
> + /* Substract the header length.
> + * In which case do we need the header length in used->len ?
> + */
> + len_adjust = _mm_set_epi16(
> + 0, 0,
> + 0,
> + (uint16_t) -sizeof(struct virtio_net_hdr),
> + 0, (uint16_t) -sizeof(struct virtio_net_hdr),
> + 0, 0);
> +
> + if (unlikely(nb_pkts < RTE_VIRTIO_DESC_PER_LOOP))
> + return 0;
> +
> + nb_used = *(volatile uint16_t *)&rxvq->vq_ring.used->idx -
> + rxvq->vq_used_cons_idx;
> +
> + rte_compiler_barrier();
> +
> + if (unlikely(nb_used == 0))
> + return 0;
> +
> + nb_pkts = RTE_ALIGN_FLOOR(nb_pkts, RTE_VIRTIO_DESC_PER_LOOP);
> + nb_used = RTE_MIN(nb_used, nb_pkts);
> +
> + desc_idx = (uint16_t)(rxvq->vq_used_cons_idx & (rxvq->vq_nentries - 1));
> + rused = &rxvq->vq_ring.used->ring[desc_idx];
> + sw_ring = &rxvq->sw_ring[desc_idx];
> + sw_ring_end = &rxvq->sw_ring[rxvq->vq_nentries];
> +
> + _mm_prefetch((const void *)rused, _MM_HINT_T0);
Wonder if the prefetch will actually help here.
Will prefetching rx_pkts[i] be more helpful?
> +
> + if (rxvq->vq_free_cnt >= RTE_VIRTIO_VPMD_RX_REARM_THRESH) {
> + virtio_rxq_rearm_vec(rxvq);
> + if (unlikely(virtqueue_kick_prepare(rxvq)))
> + virtqueue_notify(rxvq);
> + }
> +
> + for (nb_pkts_received = 0;
> + nb_pkts_received < nb_used;) {
> + __m128i desc[RTE_VIRTIO_DESC_PER_LOOP / 2];
> + __m128i mbp[RTE_VIRTIO_DESC_PER_LOOP / 2];
> + __m128i pkt_mb[RTE_VIRTIO_DESC_PER_LOOP];
> +
> + mbp[0] = _mm_loadu_si128((__m128i *)(sw_ring + 0));
> + desc[0] = _mm_loadu_si128((__m128i *)(rused + 0));
> + _mm_storeu_si128((__m128i *)&rx_pkts[0], mbp[0]);
> +
> + mbp[1] = _mm_loadu_si128((__m128i *)(sw_ring + 2));
> + desc[1] = _mm_loadu_si128((__m128i *)(rused + 2));
> + _mm_storeu_si128((__m128i *)&rx_pkts[2], mbp[1]);
> +
> + mbp[2] = _mm_loadu_si128((__m128i *)(sw_ring + 4));
> + desc[2] = _mm_loadu_si128((__m128i *)(rused + 4));
> + _mm_storeu_si128((__m128i *)&rx_pkts[4], mbp[2]);
> +
> + mbp[3] = _mm_loadu_si128((__m128i *)(sw_ring + 6));
> + desc[3] = _mm_loadu_si128((__m128i *)(rused + 6));
> + _mm_storeu_si128((__m128i *)&rx_pkts[6], mbp[3]);
> +
> + pkt_mb[1] = _mm_shuffle_epi8(desc[0], shuf_msk2);
> + pkt_mb[0] = _mm_shuffle_epi8(desc[0], shuf_msk1);
> + pkt_mb[1] = _mm_add_epi16(pkt_mb[1], len_adjust);
> + pkt_mb[0] = _mm_add_epi16(pkt_mb[0], len_adjust);
> + _mm_storeu_si128((void *)&rx_pkts[1]->rx_descriptor_fields1,
> + pkt_mb[1]);
> + _mm_storeu_si128((void *)&rx_pkts[0]->rx_descriptor_fields1,
> + pkt_mb[0]);
> +
> + pkt_mb[3] = _mm_shuffle_epi8(desc[1], shuf_msk2);
> + pkt_mb[2] = _mm_shuffle_epi8(desc[1], shuf_msk1);
> + pkt_mb[3] = _mm_add_epi16(pkt_mb[3], len_adjust);
> + pkt_mb[2] = _mm_add_epi16(pkt_mb[2], len_adjust);
> + _mm_storeu_si128((void *)&rx_pkts[3]->rx_descriptor_fields1,
> + pkt_mb[3]);
> + _mm_storeu_si128((void *)&rx_pkts[2]->rx_descriptor_fields1,
> + pkt_mb[2]);
> +
> + pkt_mb[5] = _mm_shuffle_epi8(desc[2], shuf_msk2);
> + pkt_mb[4] = _mm_shuffle_epi8(desc[2], shuf_msk1);
> + pkt_mb[5] = _mm_add_epi16(pkt_mb[5], len_adjust);
> + pkt_mb[4] = _mm_add_epi16(pkt_mb[4], len_adjust);
> + _mm_storeu_si128((void *)&rx_pkts[5]->rx_descriptor_fields1,
> + pkt_mb[5]);
> + _mm_storeu_si128((void *)&rx_pkts[4]->rx_descriptor_fields1,
> + pkt_mb[4]);
> +
> + pkt_mb[7] = _mm_shuffle_epi8(desc[3], shuf_msk2);
> + pkt_mb[6] = _mm_shuffle_epi8(desc[3], shuf_msk1);
> + pkt_mb[7] = _mm_add_epi16(pkt_mb[7], len_adjust);
> + pkt_mb[6] = _mm_add_epi16(pkt_mb[6], len_adjust);
> + _mm_storeu_si128((void *)&rx_pkts[7]->rx_descriptor_fields1,
> + pkt_mb[7]);
> + _mm_storeu_si128((void *)&rx_pkts[6]->rx_descriptor_fields1,
> + pkt_mb[6]);
> +
> + if (unlikely(nb_used <= RTE_VIRTIO_DESC_PER_LOOP)) {
> + if (sw_ring + nb_used <= sw_ring_end)
> + nb_pkts_received += nb_used;
> + else
> + nb_pkts_received += sw_ring_end - sw_ring;
> + break;
> + } else {
> + if (unlikely(sw_ring + RTE_VIRTIO_DESC_PER_LOOP >=
> + sw_ring_end)) {
> + nb_pkts_received += sw_ring_end - sw_ring;
> + break;
> + } else {
> + nb_pkts_received += RTE_VIRTIO_DESC_PER_LOOP;
> +
> + rx_pkts += RTE_VIRTIO_DESC_PER_LOOP;
> + sw_ring += RTE_VIRTIO_DESC_PER_LOOP;
> + rused += RTE_VIRTIO_DESC_PER_LOOP;
> + nb_used -= RTE_VIRTIO_DESC_PER_LOOP;
> + }
> + }
> + }
> +
> + rxvq->vq_used_cons_idx += nb_pkts_received;
> + rxvq->vq_free_cnt += nb_pkts_received;
> + rxvq->packets += nb_pkts_received;
> + return nb_pkts_received;
> +}
> +
> +int __attribute__((cold))
> +virtio_rxq_vec_setup(struct virtqueue *rxq)
> +{
> + uintptr_t p;
> + struct rte_mbuf mb_def = { .buf_addr = 0 }; /* zeroed mbuf */
> +
> + mb_def.nb_segs = 1;
> + mb_def.data_off = RTE_PKTMBUF_HEADROOM;
> + mb_def.port = rxq->port_id;
> + rte_mbuf_refcnt_set(&mb_def, 1);
> +
> + /* prevent compiler reordering: rearm_data covers previous fields */
> + rte_compiler_barrier();
> + p = (uintptr_t)&mb_def.rearm_data;
> + rxq->mbuf_initializer = *(uint64_t *)p;
> +
> + return 0;
> +}
> diff --git a/drivers/net/virtio/virtqueue.h b/drivers/net/virtio/virtqueue.h
> index 6a1ec48..98a77d5 100644
> --- a/drivers/net/virtio/virtqueue.h
> +++ b/drivers/net/virtio/virtqueue.h
> @@ -188,6 +188,7 @@ struct virtqueue {
> */
> uint16_t vq_used_cons_idx;
> uint16_t vq_avail_idx;
> + uint64_t mbuf_initializer; /**< value to init mbufs. */
> phys_addr_t virtio_net_hdr_mem; /**< hdr for each xmit packet */
>
> struct rte_mbuf **sw_ring; /**< RX software ring. */
> --
> 1.8.1.4
