RE: [PATCH v11 2/4] net/i40e: implement mbufs recycle mode

[Konstantin Ananyev <konstantin.ananyev@huawei.com>]

> >
> > Define specific function implementation for i40e driver.
> > Currently, mbufs recycle mode can support 128bit vector path and avx2 path.
> > And can be enabled both in fast free and no fast free mode.
> >
> > Suggested-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
> > Signed-off-by: Feifei Wang <feifei.wang2@arm.com>
> > Reviewed-by: Ruifeng Wang <ruifeng.wang@arm.com>
> > Reviewed-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
> > ---
> >  drivers/net/i40e/i40e_ethdev.c                |   1 +
> >  drivers/net/i40e/i40e_ethdev.h                |   2 +
> >  .../net/i40e/i40e_recycle_mbufs_vec_common.c  | 147
> > ++++++++++++++++++
> >  drivers/net/i40e/i40e_rxtx.c                  |  32 ++++
> >  drivers/net/i40e/i40e_rxtx.h                  |   4 +
> >  drivers/net/i40e/meson.build                  |   1 +
> >  6 files changed, 187 insertions(+)
> >  create mode 100644 drivers/net/i40e/i40e_recycle_mbufs_vec_common.c
> >
> > diff --git a/drivers/net/i40e/i40e_ethdev.c b/drivers/net/i40e/i40e_ethdev.c
> > index 8271bbb394..50ba9aac94 100644
> > --- a/drivers/net/i40e/i40e_ethdev.c
> > +++ b/drivers/net/i40e/i40e_ethdev.c
> > @@ -496,6 +496,7 @@ static const struct eth_dev_ops i40e_eth_dev_ops = {
> >  	.flow_ops_get                 = i40e_dev_flow_ops_get,
> >  	.rxq_info_get                 = i40e_rxq_info_get,
> >  	.txq_info_get                 = i40e_txq_info_get,
> > +	.recycle_rxq_info_get         = i40e_recycle_rxq_info_get,
> >  	.rx_burst_mode_get            = i40e_rx_burst_mode_get,
> >  	.tx_burst_mode_get            = i40e_tx_burst_mode_get,
> >  	.timesync_enable              = i40e_timesync_enable,
> > diff --git a/drivers/net/i40e/i40e_ethdev.h b/drivers/net/i40e/i40e_ethdev.h
> > index 6f65d5e0ac..af758798e1 100644
> > --- a/drivers/net/i40e/i40e_ethdev.h
> > +++ b/drivers/net/i40e/i40e_ethdev.h
> > @@ -1355,6 +1355,8 @@ void i40e_rxq_info_get(struct rte_eth_dev *dev,
> > uint16_t queue_id,
> >  	struct rte_eth_rxq_info *qinfo);
> >  void i40e_txq_info_get(struct rte_eth_dev *dev, uint16_t queue_id,
> >  	struct rte_eth_txq_info *qinfo);
> > +void i40e_recycle_rxq_info_get(struct rte_eth_dev *dev, uint16_t queue_id,
> > +	struct rte_eth_recycle_rxq_info *recycle_rxq_info);
> >  int i40e_rx_burst_mode_get(struct rte_eth_dev *dev, uint16_t queue_id,
> >  			   struct rte_eth_burst_mode *mode);  int
> > i40e_tx_burst_mode_get(struct rte_eth_dev *dev, uint16_t queue_id, diff --
> > git a/drivers/net/i40e/i40e_recycle_mbufs_vec_common.c
> > b/drivers/net/i40e/i40e_recycle_mbufs_vec_common.c
> > new file mode 100644
> > index 0000000000..5663ecccde
> > --- /dev/null
> > +++ b/drivers/net/i40e/i40e_recycle_mbufs_vec_common.c
> > @@ -0,0 +1,147 @@
> > +/* SPDX-License-Identifier: BSD-3-Clause
> > + * Copyright (c) 2023 Arm Limited.
> > + */
> > +
> > +#include <stdint.h>
> > +#include <ethdev_driver.h>
> > +
> > +#include "base/i40e_prototype.h"
> > +#include "base/i40e_type.h"
> > +#include "i40e_ethdev.h"
> > +#include "i40e_rxtx.h"
> > +
> > +#pragma GCC diagnostic ignored "-Wcast-qual"
> > +
> > +void
> > +i40e_recycle_rx_descriptors_refill_vec(void *rx_queue, uint16_t
> > +nb_mbufs) {
> > +	struct i40e_rx_queue *rxq = rx_queue;
> > +	struct i40e_rx_entry *rxep;
> > +	volatile union i40e_rx_desc *rxdp;
> > +	uint16_t rx_id;
> > +	uint64_t paddr;
> > +	uint64_t dma_addr;
> > +	uint16_t i;
> > +
> > +	rxdp = rxq->rx_ring + rxq->rxrearm_start;
> > +	rxep = &rxq->sw_ring[rxq->rxrearm_start];
> > +
> > +	for (i = 0; i < nb_mbufs; i++) {
> > +		/* Initialize rxdp descs. */
> > +		paddr = (rxep[i].mbuf)->buf_iova +
> > RTE_PKTMBUF_HEADROOM;
> > +		dma_addr = rte_cpu_to_le_64(paddr);
> > +		/* flush desc with pa dma_addr */
> > +		rxdp[i].read.hdr_addr = 0;
> > +		rxdp[i].read.pkt_addr = dma_addr;
> > +	}
> > +
> > +	/* Update the descriptor initializer index */
> > +	rxq->rxrearm_start += nb_mbufs;
> > +	rx_id = rxq->rxrearm_start - 1;
> > +
> > +	if (unlikely(rxq->rxrearm_start >= rxq->nb_rx_desc)) {
> > +		rxq->rxrearm_start = 0;
> > +		rx_id = rxq->nb_rx_desc - 1;
> > +	}
> > +
> > +	rxq->rxrearm_nb -= nb_mbufs;
> > +
> > +	rte_io_wmb();
> > +	/* Update the tail pointer on the NIC */
> > +	I40E_PCI_REG_WRITE_RELAXED(rxq->qrx_tail, rx_id); }
> > +
> > +uint16_t
> > +i40e_recycle_tx_mbufs_reuse_vec(void *tx_queue,
> > +	struct rte_eth_recycle_rxq_info *recycle_rxq_info) {
> > +	struct i40e_tx_queue *txq = tx_queue;
> > +	struct i40e_tx_entry *txep;
> > +	struct rte_mbuf **rxep;
> > +	int i, n;
> > +	uint16_t nb_recycle_mbufs;
> > +	uint16_t avail = 0;
> > +	uint16_t mbuf_ring_size = recycle_rxq_info->mbuf_ring_size;
> > +	uint16_t mask = recycle_rxq_info->mbuf_ring_size - 1;
> > +	uint16_t refill_requirement = recycle_rxq_info->refill_requirement;
> > +	uint16_t refill_head = *recycle_rxq_info->refill_head;
> > +	uint16_t receive_tail = *recycle_rxq_info->receive_tail;
> > +
> > +	/* Get available recycling Rx buffers. */
> > +	avail = (mbuf_ring_size - (refill_head - receive_tail)) & mask;
> > +
> > +	/* Check Tx free thresh and Rx available space. */
> > +	if (txq->nb_tx_free > txq->tx_free_thresh || avail <= txq->tx_rs_thresh)
> > +		return 0;
> > +
> > +	/* check DD bits on threshold descriptor */
> > +	if ((txq->tx_ring[txq->tx_next_dd].cmd_type_offset_bsz &
> > +
> > 	rte_cpu_to_le_64(I40E_TXD_QW1_DTYPE_MASK)) !=
> > +
> > 	rte_cpu_to_le_64(I40E_TX_DESC_DTYPE_DESC_DONE))
> > +		return 0;
> > +
> > +	n = txq->tx_rs_thresh;
> > +	nb_recycle_mbufs = n;
> > +
> > +	/* Mbufs recycle mode can only support no ring buffer wrapping
> > around.
> > +	 * Two case for this:
> > +	 *
> > +	 * case 1: The refill head of Rx buffer ring needs to be aligned with
> > +	 * mbuf ring size. In this case, the number of Tx freeing buffers
> > +	 * should be equal to refill_requirement.
> > +	 *
> > +	 * case 2: The refill head of Rx ring buffer does not need to be aligned
> > +	 * with mbuf ring size. In this case, the update of refill head can not
> > +	 * exceed the Rx mbuf ring size.
> > +	 */
> > +	if (refill_requirement != n ||
> > +		(!refill_requirement && (refill_head + n > mbuf_ring_size)))
> > +		return 0;
> > +
> > +	/* First buffer to free from S/W ring is at index
> > +	 * tx_next_dd - (tx_rs_thresh-1).
> > +	 */
> > +	txep = &txq->sw_ring[txq->tx_next_dd - (n - 1)];
> > +	rxep = recycle_rxq_info->mbuf_ring;
> > +	rxep += refill_head;
> > +
> > +	if (txq->offloads & RTE_ETH_TX_OFFLOAD_MBUF_FAST_FREE) {
> > +		/* Avoid txq contains buffers from unexpected mempool. */
> > +		if (unlikely(recycle_rxq_info->mp
> > +					!= txep[0].mbuf->pool))
> > +			return 0;
> > +
> > +		/* Directly put mbufs from Tx to Rx. */
> > +		for (i = 0; i < n; i++)
> > +			rxep[i] = txep[i].mbuf;
> > +	} else {
> > +		for (i = 0; i < n; i++) {
> > +			rxep[i] = rte_pktmbuf_prefree_seg(txep[i].mbuf);
> > +
> > +			/* If Tx buffers are not the last reference or from
> > +			 * unexpected mempool, previous copied buffers are
> > +			 * considered as invalid.
> > +			 */
> > +			if (unlikely((rxep[i] == NULL && refill_requirement) ||
> [Konstantin]
> Could you pls remind me why it is ok to have rxep[i]==NULL when
> refill_requirement is not set?
> 
> If reill_requirement is not zero, it means each tx freed buffer must be valid and can be put into Rx
> sw_ring. Then  the refill head of Rx buffer ring can be aligned with mbuf ring size. Briefly speaking
> the number of Tx valid freed buffer must be equal to Rx refill_requirement. For example, i40e driver.
> 
> If reill_requirement is zero, it means that the refill head of Rx buffer ring does not need to be aligned
> with mbuf ring size, thus if Tx have n valid freed buffers, we just need to put these n buffers into Rx sw-ring,
> and not to be equal to the Rx setting rearm number. For example, mlx5 driver.
> 
> In conclusion, above difference is due to pmd drivers have different strategies to update their Rx rearm(refill) head.
> For i40e driver, if rearm_head exceed 1024, it will be set as 0 due to  the number of each rearm is a fixed value by default.
> For mlx5 driver. Its rearm_head can exceed 1024, and use mask to achieve real index. Thus its rearm number can be a different value.

Ok, but if rte_pktmbuf_prefree_seg(txep[i].mbuf), it means that this mbuf is not free yet and can't be reused.
Shouldn't we then set nb_recycle_mbufs = 0 in that case too?
Or probably would be enough to skip that mbuf?
Might be something like that:

for (i = 0, j = 0; i < n; i++) {

	rxep[j] = rte_pktmbuf_prefree_seg(txep[i].mbuf);
	if (rxep[j] == NULL || recycle_rxq_info->mp != rxep[j].mbuf->pool))  {
		if (refill_requirement) {
			nb_recycle_mbufs = 0;
			break; 
		}
	} else
		j++;
}

/* now j contains actual number of recycled mbufs */

?

> 
> > +					recycle_rxq_info->mp != txep[i].mbuf-
> > >pool))
> > +				nb_recycle_mbufs = 0;
> > +		}
> > +		/* If Tx buffers are not the last reference or
> > +		 * from unexpected mempool, all recycled buffers
> > +		 * are put into mempool.
> > +		 */
> > +		if (nb_recycle_mbufs == 0)
> > +			for (i = 0; i < n; i++) {
> > +				if (rxep[i] != NULL)
> > +					rte_mempool_put(rxep[i]->pool,
> > rxep[i]);
> > +			}
> > +	}
> > +
> > +	/* Update counters for Tx. */
> > +	txq->nb_tx_free = (uint16_t)(txq->nb_tx_free + txq->tx_rs_thresh);
> > +	txq->tx_next_dd = (uint16_t)(txq->tx_next_dd + txq->tx_rs_thresh);
> > +	if (txq->tx_next_dd >= txq->nb_tx_desc)
> > +		txq->tx_next_dd = (uint16_t)(txq->tx_rs_thresh - 1);
> > +
> > +	return nb_recycle_mbufs;
> > +}
> > diff --git a/drivers/net/i40e/i40e_rxtx.c b/drivers/net/i40e/i40e_rxtx.c index
> > b4f65b58fa..a9c9eb331c 100644
> > --- a/drivers/net/i40e/i40e_rxtx.c
> > +++ b/drivers/net/i40e/i40e_rxtx.c
> > @@ -3199,6 +3199,30 @@ i40e_txq_info_get(struct rte_eth_dev *dev,
> > uint16_t queue_id,
> >  	qinfo->conf.offloads = txq->offloads;
> >  }
> >
> > +void
> > +i40e_recycle_rxq_info_get(struct rte_eth_dev *dev, uint16_t queue_id,
> > +	struct rte_eth_recycle_rxq_info *recycle_rxq_info) {
> > +	struct i40e_rx_queue *rxq;
> > +	struct i40e_adapter *ad =
> > +		I40E_DEV_PRIVATE_TO_ADAPTER(dev->data->dev_private);
> > +
> > +	rxq = dev->data->rx_queues[queue_id];
> > +
> > +	recycle_rxq_info->mbuf_ring = (void *)rxq->sw_ring;
> > +	recycle_rxq_info->mp = rxq->mp;
> > +	recycle_rxq_info->mbuf_ring_size = rxq->nb_rx_desc;
> > +	recycle_rxq_info->receive_tail = &rxq->rx_tail;
> > +
> > +	if (ad->rx_vec_allowed) {
> > +		recycle_rxq_info->refill_requirement =
> > RTE_I40E_RXQ_REARM_THRESH;
> > +		recycle_rxq_info->refill_head = &rxq->rxrearm_start;
> > +	} else {
> > +		recycle_rxq_info->refill_requirement = rxq->rx_free_thresh;
> > +		recycle_rxq_info->refill_head = &rxq->rx_free_trigger;
> > +	}
> > +}
> > +
> >  #ifdef RTE_ARCH_X86
> >  static inline bool
> >  get_avx_supported(bool request_avx512)
> > @@ -3293,6 +3317,8 @@ i40e_set_rx_function(struct rte_eth_dev *dev)
> >  				dev->rx_pkt_burst = ad->rx_use_avx2 ?
> >  					i40e_recv_scattered_pkts_vec_avx2 :
> >  					i40e_recv_scattered_pkts_vec;
> > +				dev->recycle_rx_descriptors_refill =
> > +					i40e_recycle_rx_descriptors_refill_vec;
> >  			}
> >  		} else {
> >  			if (ad->rx_use_avx512) {
> > @@ -3311,9 +3337,12 @@ i40e_set_rx_function(struct rte_eth_dev *dev)
> >  				dev->rx_pkt_burst = ad->rx_use_avx2 ?
> >  					i40e_recv_pkts_vec_avx2 :
> >  					i40e_recv_pkts_vec;
> > +				dev->recycle_rx_descriptors_refill =
> > +					i40e_recycle_rx_descriptors_refill_vec;
> >  			}
> >  		}
> >  #else /* RTE_ARCH_X86 */
> > +		dev->recycle_rx_descriptors_refill =
> > +i40e_recycle_rx_descriptors_refill_vec;
> >  		if (dev->data->scattered_rx) {
> >  			PMD_INIT_LOG(DEBUG,
> >  				     "Using Vector Scattered Rx (port %d).", @@
> > -3481,15 +3510,18 @@ i40e_set_tx_function(struct rte_eth_dev *dev)
> >  				dev->tx_pkt_burst = ad->tx_use_avx2 ?
> >  						    i40e_xmit_pkts_vec_avx2 :
> >  						    i40e_xmit_pkts_vec;
> > +				dev->recycle_tx_mbufs_reuse =
> > i40e_recycle_tx_mbufs_reuse_vec;
> >  			}
> >  #else /* RTE_ARCH_X86 */
> >  			PMD_INIT_LOG(DEBUG, "Using Vector Tx (port %d).",
> >  				     dev->data->port_id);
> >  			dev->tx_pkt_burst = i40e_xmit_pkts_vec;
> > +			dev->recycle_tx_mbufs_reuse =
> > i40e_recycle_tx_mbufs_reuse_vec;
> >  #endif /* RTE_ARCH_X86 */
> >  		} else {
> >  			PMD_INIT_LOG(DEBUG, "Simple tx finally be used.");
> >  			dev->tx_pkt_burst = i40e_xmit_pkts_simple;
> > +			dev->recycle_tx_mbufs_reuse =
> > i40e_recycle_tx_mbufs_reuse_vec;
> >  		}
> >  		dev->tx_pkt_prepare = i40e_simple_prep_pkts;
> >  	} else {
> > diff --git a/drivers/net/i40e/i40e_rxtx.h b/drivers/net/i40e/i40e_rxtx.h index
> > a8686224e5..b191f23e1f 100644
> > --- a/drivers/net/i40e/i40e_rxtx.h
> > +++ b/drivers/net/i40e/i40e_rxtx.h
> > @@ -236,6 +236,10 @@ uint32_t i40e_dev_rx_queue_count(void
> > *rx_queue);  int i40e_dev_rx_descriptor_status(void *rx_queue, uint16_t
> > offset);  int i40e_dev_tx_descriptor_status(void *tx_queue, uint16_t offset);
> >
> > +uint16_t i40e_recycle_tx_mbufs_reuse_vec(void *tx_queue,
> > +		struct rte_eth_recycle_rxq_info *recycle_rxq_info); void
> > +i40e_recycle_rx_descriptors_refill_vec(void *rx_queue, uint16_t
> > +nb_mbufs);
> > +
> >  uint16_t i40e_recv_pkts_vec(void *rx_queue, struct rte_mbuf **rx_pkts,
> >  			    uint16_t nb_pkts);
> >  uint16_t i40e_recv_scattered_pkts_vec(void *rx_queue, diff --git
> > a/drivers/net/i40e/meson.build b/drivers/net/i40e/meson.build index
> > 8e53b87a65..3b1a233c84 100644
> > --- a/drivers/net/i40e/meson.build
> > +++ b/drivers/net/i40e/meson.build
> > @@ -34,6 +34,7 @@ sources = files(
> >          'i40e_tm.c',
> >          'i40e_hash.c',
> >          'i40e_vf_representor.c',
> > +	'i40e_recycle_mbufs_vec_common.c',
> >          'rte_pmd_i40e.c',
> >  )
> >
> > --
> > 2.25.1