Re: [dpdk-dev] [PATCH v9 3/4] net/ixgbe: cleanup Tx buffers

[Ferruh Yigit <ferruh.yigit@intel.com>]

On 1/13/2020 9:57 AM, Chenxu Di wrote:
> Add support to the ixgbe driver for the API rte_eth_tx_done_cleanup
> to force free consumed buffers on Tx ring.
> 
> Signed-off-by: Chenxu Di <chenxux.di@intel.com>
> ---
>  drivers/net/ixgbe/ixgbe_ethdev.c |   2 +
>  drivers/net/ixgbe/ixgbe_rxtx.c   | 109 +++++++++++++++++++++++++++++++
>  drivers/net/ixgbe/ixgbe_rxtx.h   |   2 +-
>  3 files changed, 112 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ixgbe/ixgbe_ethdev.c b/drivers/net/ixgbe/ixgbe_ethdev.c
> index 2c6fd0f13..75bdd391a 100644
> --- a/drivers/net/ixgbe/ixgbe_ethdev.c
> +++ b/drivers/net/ixgbe/ixgbe_ethdev.c
> @@ -601,6 +601,7 @@ static const struct eth_dev_ops ixgbe_eth_dev_ops = {
>  	.udp_tunnel_port_add  = ixgbe_dev_udp_tunnel_port_add,
>  	.udp_tunnel_port_del  = ixgbe_dev_udp_tunnel_port_del,
>  	.tm_ops_get           = ixgbe_tm_ops_get,
> +	.tx_done_cleanup      = ixgbe_dev_tx_done_cleanup,
>  };
>  
>  /*
> @@ -649,6 +650,7 @@ static const struct eth_dev_ops ixgbevf_eth_dev_ops = {
>  	.reta_query           = ixgbe_dev_rss_reta_query,
>  	.rss_hash_update      = ixgbe_dev_rss_hash_update,
>  	.rss_hash_conf_get    = ixgbe_dev_rss_hash_conf_get,
> +	.tx_done_cleanup      = ixgbe_dev_tx_done_cleanup,
>  };
>  
>  /* store statistics names and its offset in stats structure */
> diff --git a/drivers/net/ixgbe/ixgbe_rxtx.c b/drivers/net/ixgbe/ixgbe_rxtx.c
> index fa572d184..a2e85ed5b 100644
> --- a/drivers/net/ixgbe/ixgbe_rxtx.c
> +++ b/drivers/net/ixgbe/ixgbe_rxtx.c
> @@ -2306,6 +2306,115 @@ ixgbe_tx_queue_release_mbufs(struct ixgbe_tx_queue *txq)
>  	}
>  }
>  
> +static int
> +ixgbe_tx_done_cleanup_full(struct ixgbe_tx_queue *txq, uint32_t free_cnt)
> +{
> +	struct ixgbe_tx_entry *swr_ring = txq->sw_ring;
> +	uint16_t i, tx_last, tx_id;
> +	uint16_t nb_tx_free_last;
> +	uint16_t nb_tx_to_clean;
> +	uint32_t pkt_cnt;
> +
> +	/* Start free mbuf from the next of tx_tail */
> +	tx_last = txq->tx_tail;
> +	tx_id  = swr_ring[tx_last].next_id;
> +
> +	if (txq->nb_tx_free == 0 && ixgbe_xmit_cleanup(txq))
> +		return 0;
> +
> +	nb_tx_to_clean = txq->nb_tx_free;
> +	nb_tx_free_last = txq->nb_tx_free;
> +	if (!free_cnt)
> +		free_cnt = txq->nb_tx_desc;
> +
> +	/* Loop through swr_ring to count the amount of
> +	 * freeable mubfs and packets.
> +	 */
> +	for (pkt_cnt = 0; pkt_cnt < free_cnt; ) {
> +		for (i = 0; i < nb_tx_to_clean &&
> +			pkt_cnt < free_cnt &&
> +			tx_id != tx_last; i++) {
> +			if (swr_ring[tx_id].mbuf != NULL) {
> +				rte_pktmbuf_free_seg(swr_ring[tx_id].mbuf);
> +				swr_ring[tx_id].mbuf = NULL;
> +
> +				/*
> +				 * last segment in the packet,
> +				 * increment packet count
> +				 */
> +				pkt_cnt += (swr_ring[tx_id].last_id == tx_id);
> +			}
> +
> +			tx_id = swr_ring[tx_id].next_id;
> +		}
> +
> +		if (txq->tx_rs_thresh > txq->nb_tx_desc -
> +			txq->nb_tx_free || tx_id == tx_last)
> +			break;
> +
> +		if (pkt_cnt < free_cnt) {
> +			if (ixgbe_xmit_cleanup(txq))
> +				break;
> +
> +			nb_tx_to_clean = txq->nb_tx_free - nb_tx_free_last;
> +			nb_tx_free_last = txq->nb_tx_free;
> +		}
> +	}
> +
> +	return (int)pkt_cnt;
> +}
> +
> +static int
> +ixgbe_tx_done_cleanup_simple(struct ixgbe_tx_queue *txq,
> +			uint32_t free_cnt)
> +{
> +	int i, n, cnt;
> +
> +	if (free_cnt == 0 || free_cnt > txq->nb_tx_desc)
> +		free_cnt = txq->nb_tx_desc;
> +
> +	cnt = free_cnt - free_cnt % txq->tx_rs_thresh;
> +
> +	for (i = 0; i < cnt; i += n) {
> +		if (txq->nb_tx_desc - txq->nb_tx_free < txq->tx_rs_thresh)
> +			break;
> +
> +		n = ixgbe_tx_free_bufs(txq);
> +
> +		if (n == 0)
> +			break;
> +	}
> +
> +	return i;
> +}
> +
> +static int
> +ixgbe_tx_done_cleanup_vec(struct ixgbe_tx_queue *txq __rte_unused,
> +			uint32_t free_cnt __rte_unused)
> +{
> +	return -ENOTSUP;
> +}
> +
> +int
> +ixgbe_dev_tx_done_cleanup(void *tx_queue, uint32_t free_cnt)
> +{
> +	struct ixgbe_tx_queue *txq = (struct ixgbe_tx_queue *)tx_queue;
> +	if (txq->offloads == 0 &&
> +#ifdef RTE_LIBRTE_SECURITY
> +			!(txq->using_ipsec) &&
> +#endif
> +			txq->tx_rs_thresh >= RTE_PMD_IXGBE_TX_MAX_BURST)
> +#ifdef RTE_IXGBE_INC_VECTOR
> +		if (txq->tx_rs_thresh <= RTE_IXGBE_TX_MAX_FREE_BUF_SZ &&
> +				(rte_eal_process_type() != RTE_PROC_PRIMARY ||
> +					txq->sw_ring_v != NULL))
> +			return ixgbe_tx_done_cleanup_vec(txq, free_cnt);
> +#endif
> +		return ixgbe_tx_done_cleanup_simple(txq, free_cnt);
> +
> +	return ixgbe_tx_done_cleanup_full(txq, free_cnt);
> +}
> +

Missing curly parantheses in the 'if' blocks are causing confusion on which
return patch to take.

the above code is like this:
if (txq->offloads == 0 && ...)
  if (txq->tx_rs_thresh <= RTE_IXGBE_TX_MAX_FREE_BUF_SZ && ...)
    return ixgbe_tx_done_cleanup_vec(txq, free_cnt);
  return ixgbe_tx_done_cleanup_simple(txq, free_cnt); <----- [*]
return ixgbe_tx_done_cleanup_full(txq, free_cnt);

It is not clear, and looks like wrong based on indentation, when to get the [*]
path above.

I will add curly parantheses while merging.

Btw, why we need "#ifdef RTE_IXGBE_INC_VECTOR" here, can't we remove it?