Re: [dpdk-dev] [PATCH V4 4/4] net/i40e: FDIR update rate optimization

["Sun, Chenmin" <chenmin.sun@intel.com>]

Best Regards,
Sun, Chenmin

> -----Original Message-----
> From: Wu, Jingjing <jingjing.wu@intel.com>
> Sent: Thursday, July 16, 2020 9:57 PM
> To: Sun, Chenmin <chenmin.sun@intel.com>; Zhang, Qi Z
> <qi.z.zhang@intel.com>; Xing, Beilei <beilei.xing@intel.com>; Wang, Haiyue
> <haiyue.wang@intel.com>
> Cc: dev@dpdk.org
> Subject: RE: [PATCH V4 4/4] net/i40e: FDIR update rate optimization
> 
> 
> [...]
> 
> > +static inline unsigned char *
> > +i40e_find_available_buffer(struct rte_eth_dev *dev) {
> > +	struct i40e_pf *pf = I40E_DEV_PRIVATE_TO_PF(dev->data-
> >dev_private);
> > +	struct i40e_fdir_info *fdir_info = &pf->fdir;
> > +	struct i40e_tx_queue *txq = pf->fdir.txq;
> > +	volatile struct i40e_tx_desc *txdp = &txq->tx_ring[txq->tx_tail + 1];
> > +	uint32_t i;
> > +
> > +	/* no available buffer
> > +	 * search for more available buffers from the current
> > +	 * descriptor, until an unavailable one
> > +	 */
> > +	if (fdir_info->txq_available_buf_count <= 0) {
> > +		uint16_t tmp_tail;
> > +		volatile struct i40e_tx_desc *tmp_txdp;
> > +
> > +		tmp_tail = txq->tx_tail;
> > +		tmp_txdp = &txq->tx_ring[tmp_tail + 1];
> > +
> > +		do {
> > +			if ((tmp_txdp->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))
> > +				fdir_info->txq_available_buf_count++;
> > +			else
> > +				break;
> > +
> > +			tmp_tail += 2;
> > +			if (tmp_tail >= txq->nb_tx_desc)
> > +				tmp_tail = 0;
> > +		} while (tmp_tail != txq->tx_tail);
> > +	}
> > +
> > +	/*
> > +	 * if txq_available_buf_count > 0, just use the next one is ok,
> > +	 * else wait for the next DD until it's set to make sure the data
> > +	 * had been fetched by hardware
> > +	 */
> > +	if (fdir_info->txq_available_buf_count > 0) {
> > +		fdir_info->txq_available_buf_count--;
> > +	} else {
> > +		/* wait until the tx descriptor is ready */
> > +		for (i = 0; i < I40E_FDIR_MAX_WAIT_US; i++) {
> > +			if ((txdp->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))
> > +				break;
> > +			rte_delay_us(1);
> > +		}
> > +		if (i >= I40E_FDIR_MAX_WAIT_US) {
> > +			PMD_DRV_LOG(ERR,
> > +			    "Failed to program FDIR filter: time out to get DD on
> tx
> > queue.");
> > +			return NULL;
> > +		}
> > +	}
> Why wait for I40E_FDIR_MAX_WAIT_US but not return NULL immediately?

Done

> [...]
> 
> 
> >  i40e_flow_fdir_filter_programming(struct i40e_pf *pf,
> >  				  enum i40e_filter_pctype pctype,
> >  				  const struct i40e_fdir_filter_conf *filter,
> > -				  bool add)
> > +				  bool add, bool wait_status)
> >  {
> >  	struct i40e_tx_queue *txq = pf->fdir.txq;
> >  	struct i40e_rx_queue *rxq = pf->fdir.rxq; @@ -2011,8 +2092,10 @@
> > i40e_flow_fdir_filter_programming(struct i40e_pf *pf,
> >  	volatile struct i40e_tx_desc *txdp;
> >  	volatile struct i40e_filter_program_desc *fdirdp;
> >  	uint32_t td_cmd;
> > -	uint16_t vsi_id, i;
> > +	uint16_t vsi_id;
> >  	uint8_t dest;
> > +	uint32_t i;
> > +	uint8_t retry_count = 0;
> >
> >  	PMD_DRV_LOG(INFO, "filling filter programming descriptor.");
> >  	fdirdp = (volatile struct i40e_filter_program_desc *) @@ -2087,7
> > +2170,8 @@ i40e_flow_fdir_filter_programming(struct i40e_pf *pf,
> >
> >  	PMD_DRV_LOG(INFO, "filling transmit descriptor.");
> >  	txdp = &txq->tx_ring[txq->tx_tail + 1];
> > -	txdp->buffer_addr = rte_cpu_to_le_64(pf->fdir.dma_addr);
> > +	txdp->buffer_addr = rte_cpu_to_le_64(pf->fdir.dma_addr[txq->tx_tail
> > +/ 2]);
> > +
> [txq->tx_tail / 2] is not readable, how about use the avail pkt you get directly?
> Or another index to identify it?

Have replaced with >> 1

> >  	td_cmd = I40E_TX_DESC_CMD_EOP |
> >  		 I40E_TX_DESC_CMD_RS  |
> >  		 I40E_TX_DESC_CMD_DUMMY;
> > @@ -2100,25 +2184,34 @@ i40e_flow_fdir_filter_programming(struct
> i40e_pf *pf,
> >  		txq->tx_tail = 0;
> >  	/* Update the tx tail register */
> >  	rte_wmb();
> > +
> > +	/* capture the previous error report(if any) from rx ring */
> > +	while ((i40e_check_fdir_programming_status(rxq) < 0) &&
> > +		(++retry_count < 100))
> > +		PMD_DRV_LOG(INFO, "previous error report captured.");
> > +
> Why check FDIR ring for 100 times? And "&&" is used here, the log is only print if
> the 100th check fails?
No, it will print 100 times.
The purpose of this code is to clean up the fdir rx queue.
Have new an independent function for this

> >
> > --
> > 2.17.1