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

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

Hi Feifei,

> > > -----Original Message-----
> > > From: Feifei Wang
> > > Sent: Tuesday, September 5, 2023 11:11 AM
> > > To: Konstantin Ananyev <konstantin.ananyev@huawei.com>; Konstantin
> > > Ananyev <konstantin.v.ananyev@yandex.ru>
> > > Cc: dev@dpdk.org; nd <nd@arm.com>; Honnappa Nagarahalli
> > > <Honnappa.Nagarahalli@arm.com>; Ruifeng Wang
> > <Ruifeng.Wang@arm.com>;
> > > Yuying Zhang <Yuying.Zhang@intel.com>; Beilei Xing
> > > <beilei.xing@intel.com>; nd <nd@arm.com>; nd <nd@arm.com>; nd
> > > <nd@arm.com>; nd <nd@arm.com>; nd <nd@arm.com>
> > > Subject: RE: [PATCH v11 2/4] net/i40e: implement mbufs recycle mode
> > >
> > >
> > >
> > > > -----Original Message-----
> > > > From: Konstantin Ananyev <konstantin.ananyev@huawei.com>
> > > > Sent: Monday, September 4, 2023 6:22 PM
> > > > To: Feifei Wang <Feifei.Wang2@arm.com>; Konstantin Ananyev
> > > > <konstantin.v.ananyev@yandex.ru>
> > > > Cc: dev@dpdk.org; nd <nd@arm.com>; Honnappa Nagarahalli
> > > > <Honnappa.Nagarahalli@arm.com>; Ruifeng Wang
> > > <Ruifeng.Wang@arm.com>;
> > > > Yuying Zhang <Yuying.Zhang@intel.com>; Beilei Xing
> > > > <beilei.xing@intel.com>; nd <nd@arm.com>; nd <nd@arm.com>; nd
> > > > <nd@arm.com>; nd <nd@arm.com>
> > > > Subject: RE: [PATCH v11 2/4] net/i40e: implement mbufs recycle mode
> > > >
> > > >
> > > >
> > > > > > > > > > > > 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]);
> > > > > > > > > > > > +			}
> > > > > > > > > > > > +	}
> > > > > > > > > > > > +
> > > > > > > > > [Konstantin] After another thought, it might be easier and
> > > > > > > > > cleaner
> > > > just to:
> > > > > > > > > if (rxep[j] == NULL || recycle_rxq_info->mp != rxep[j].mbuf->pool)
> > > > > > > > > 	nb_recycle_mbufs = 0;
> > > > > > > > >
> > > > > > > > > Anyway, from my understanding - if
> > > > > > > > > rte_pktmbuf_prefree_seg(mbuf) returns NULL, then we can't
> > > > > > > > > recycle
> > > > that mbuf.
> > > > > > > > >
> > > > > > > > > [Feifei] Agree with that 'rte_pktmbuf_prefree_seg(mbuf)
> > > > > > > > > returns NULL, then
> > > > > > > > we can't recycle that mbuf'.
> > > > > > > > >
> > > > > > > > > Firstly, we should know for i40e driver,  the number of
> > > > > > > > > free mbufs is fixed, it
> > > > > > > > must equal to 'tx_rs_thresh'
> > > > > > > > > This means if we start to free Tx mbufs, it cannot be
> > > > > > > > > interrupted until the
> > > > > > > > given amount of mbufs are freed.
> > > > > > > > > In the meanwhile, doing prefree operation for a Tx mbuf
> > > > > > > > > can be looked at this mbuf is freed from this TX sw-ring
> > > > > > > > > if the API returns NULL. This is due
> > > > > > > > to that call 'prefree_seg' function means update the mbuf refcnt.
> > > > > > > > >
> > > > > > > > > So let's come back our recycle mbuf case.
> > > > > > > > > Here we consider that the case if we have 32 mbufs need to
> > > > > > > > > be freed, and
> > > > > > > > we firstly do the pre-free.
> > > > > > > > > And then first 8 mbufs is good and return value is not none.
> > > > > > > > > But the 9th
> > > > > > > > mbuf is bad, its refcnt is more than 1.
> > > > > > > > > So we just update its refcnt and cannot put it into Rx sw-ring.
> > > > > > > > > For Tx sw-ring,
> > > > > > > > this mbuf has been freed.
> > > > > > > > > Then we should continue to do pre-free operation for the
> > > > > > > > > next Tx mbufs to ensure the given amount of mbufs are freed.
> > > > > > > > >
> > > > > > > > > Do a conclusion for this, this is because if we start to
> > > > > > > > > do pre-free operation,  the Tx mbuf refcnt value maybe
> > > > > > > > > changed, so we cannot stop or
> > > > > > > > break until finish all the pre-free operation.
> > > > > > > > >
> > > > > > > > > Finally, in the case that Rx refill_request is not zero,
> > > > > > > > > but the valid mbuf amount is less than this value, we must
> > > > > > > > > put back this Tx mbufs into
> > > > > > > > mempool.
> > > > > > > > >
> > > > > > > > > Above is the reason why I do not directly jump out of the
> > > > > > > > > loop if some mbuf
> > > > > > > > return value is NULL.
> > > > > > > >
> > > > > > > > Yep, I already realized that it is a bit more complicated
> > > > > > > > and we need to continue with prefree() for all packets even
> > > > > > > > when we get NULL in
> > > > > > the middle.
> > > > > > > > Anyway the code has to be changed, right?
> > > > > > > >
> > > > > > > Sorry, I think for the code, it is unnecessary to be changed.
> > > > > > > For no fast free path, currently:
> > > > > > > 1.   We check whether each mbuf is Ok and call pre_free function
> > > > > > > --------------------------------------------------------------
> > > > > > > --
> > > > > > > --
> > > > > > > ----
> > > > > > > --------------------------------------------------------------
> > > > > > > 2.1 For the mbuf return value is not NULL, it is put into Rx sw-ring.
> > > > > > > 2.2 For the mbuf return value is zero and refill-request, it
> > > > > > > will also firstly put into Rx sw-ring, and we set nb_recycle =
> > > > > > > 0
> > > > > > > --------------------------------------------------------------
> > > > > > > --
> > > > > > > --
> > > > > > > ----
> > > > > > > --------------------------------------------------------------
> > > > > > > 3.1 We check nb_recycle, if it is not 0, we will continue to
> > > > > > > rearm Rx descs
> > > > > > and update its index by call descs_refill function.
> > > > > > > 3.2 if nb_recycle is 0, we will put valid recycle mbufs back
> > > > > > > into mempool as general path. This is necessary, because we
> > > > > > > need to ensure the freed Tx number is fixed.(Some buffers
> > > > > > > return is null can be seen as freed, others need to be put
> > > > > > > into mempool)
> > > > > > >
> > > > > > > Or maybe I ignore something?
> > > > > >
> > > > > >
> > > > > > I am talking about the case when both refill_requirement and
> > > > > > mbuf return values iare zero:
> > > > > > if (unlikely((rxep[i] == NULL && refill_requirement) ||         // ???
> > rxep[i]
> > > ==
> > > > 0
> > > > > > AND refill_requirement == 0 ???
> > > > > >  		recycle_rxq_info->mp != txep[i].mbuf->pool))
> > > > > > 	nb_recycle_mbufs = 0;
> > > > > >
> > > > > > As I can read the code you treat such situation as valid, while
> > > > > > I think we should reset nb_recycle_mbufs to zero when rxep[i] ==
> > > > > > NULL, no matter what value refill_requirement is.
> > > > >
> > > > > So this means for maybe MLX5 driver, its refill_request = 0. And
> > > > > if some mbufs return value is zero, the other mbufs can not be
> > > > > recycled into Rx sw-ring? Because nb_recycle=0, and they need to
> > > > > be put into
> > > > mempool.
> > > > >
> > > > > I think for such as MLX5 driver, we can allow recycle some valid
> > > > > mbufs into
> > > > Rx ring.
> > > > > Because no constraint for its refill number. Is my suggestion reasonable?
> > > >
> > > > I suppose yes: if refill_request is zero we potentially can skip 'bad'
> > > > mbufs and continue with recycling for remaining ones.
> > > > It would probably require more changes in current code, but sounds
> > > > ok to me in general.
> > > That's Ok. Thanks for your careful reviewing.
> >
> > I'm very sorry not to receive your e-mail and until now I realize we need to do
> > some code change for i40e driver. Also thanks ferruh to kindly remind this.

No worries at all and thanks for you and Ferruh fro fast reaction.
 
> >
> > Agree with you we need some operation for the case that (refill_requirement
> > == 0 &&  rxep[i] == 0).
> > Thus maybe we can do a change as follows:
> >
> > for (i = 0; i < n; i++) {
> > 	rxep[0] = rte_pktmbuf_prefree_seg(txep[i].mbuf);
> > 	if (unlikely((rxep[0] == NULL && refill_requirement) ||
> > 			recycle_rxq_info->mp != txep[i].mbuf->pool))
> > 		nb_recycle_mbufs = 0;
> > 	if (likely(rxep[0]))
> > 		rxep++;
> > }
> >
> > Is above change is Ok?
> >
> 
> Just do a change for the above code:
> -----------------------------------------------------------------------------------------------------
> int j = 0;
> ......
> 
>  for (i = 0; i < n; i++) {
>  	rxep[j] = rte_pktmbuf_prefree_seg(txep[i].mbuf);
> 	if (unlikely(rxep[j] == NULL  && !refill_requirement))
>  		continue;
> 	if (unlikely((rxep[j] == NULL && refill_requirement) ||
>  			recycle_rxq_info->mp != txep[i].mbuf->pool))
>  		nb_recycle_mbufs  = 0;
> 	j++;
>  }
> 
> if (nb_recycle_mbufs  == 0)
> 	for (i = 0; i < j; i++) {
> 		if (rxep[i] != NULL)
> 			rte_mempool_put(rxep[i]->pool, rxep[i]);
> 	}

I think it should work...
One more thing, shouldn't we reset
nb_recycle_mbufs  = j;

Something like:
 if (nb_recycle_mbufs  == 0) {
 	for (i = 0; i < j; i++) {
 		if (rxep[i] != NULL)
 			rte_mempool_put(rxep[i]->pool, rxep[i]);
 	}
} else
  nb_recycle_mbufs  = j;

? 



 


> ---------------------------------------------------------------------------------------------------------
> > > >
> > > > > >
> > > > > >
> > > > > > > > >
> > > > > > > > > > > > +	/* 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