Re: [PATCH v2] net/mlx5: setup RSS regardless of queue count

["Nélio Laranjeiro" <nelio.laranjeiro@6wind.com>]

On Wed, Mar 21, 2018 at 01:47:51PM +0100, Nelio Laranjeiro wrote:
> From: Dahir Osman <dahir.osman@windriver.com>
> 
> In some environments it is desirable to have the NIC perform RSS
> normally on the packet regardless of the number of queues configured.
> The RSS hash result that is stored in the mbuf can then be used by
> the application to make decisions about how to distribute workloads
> to threads, secondary processes, or even virtual machines if the
> application is a virtual switch.  This change to the mlx5 driver
> aligns with how other drivers in the Intel family work.
> 
> Signed-off-by: Allain Legacy <allain.legacy@windriver.com>
> Signed-off-by: Nelio Laranjeiro <nelio.laranjeiro@6wind.com>
> ---
>  drivers/net/mlx5/mlx5_flow.c |  2 +-
>  drivers/net/mlx5/mlx5_rss.c  | 10 ++++++++++
>  drivers/net/mlx5/mlx5_rxq.c  |  3 ++-
>  3 files changed, 13 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/mlx5/mlx5_flow.c b/drivers/net/mlx5/mlx5_flow.c
> index 3eecdc604..49600e174 100644
> --- a/drivers/net/mlx5/mlx5_flow.c
> +++ b/drivers/net/mlx5/mlx5_flow.c
> @@ -909,7 +909,7 @@ mlx5_flow_convert_finalise(struct mlx5_flow_parse *parser)
>  	unsigned int i;
>  
>  	/* Remove any other flow not matching the pattern. */
> -	if (parser->queues_n == 1) {
> +	if (parser->queues_n == 1 && !parser->rss_conf.rss_hf) {
>  		for (i = 0; i != hash_rxq_init_n; ++i) {
>  			if (i == HASH_RXQ_ETH)
>  				continue;
> diff --git a/drivers/net/mlx5/mlx5_rss.c b/drivers/net/mlx5/mlx5_rss.c
> index 5ac650163..c490854e1 100644
> --- a/drivers/net/mlx5/mlx5_rss.c
> +++ b/drivers/net/mlx5/mlx5_rss.c
> @@ -42,6 +42,8 @@ mlx5_rss_hash_update(struct rte_eth_dev *dev,
>  		     struct rte_eth_rss_conf *rss_conf)
>  {
>  	struct priv *priv = dev->data->dev_private;
> +	unsigned int i;
> +	unsigned int idx;
>  
>  	if (rss_conf->rss_hf & MLX5_RSS_HF_MASK) {
>  		rte_errno = EINVAL;
> @@ -59,6 +61,14 @@ mlx5_rss_hash_update(struct rte_eth_dev *dev,
>  		priv->rss_conf.rss_key_len = rss_conf->rss_key_len;
>  	}
>  	priv->rss_conf.rss_hf = rss_conf->rss_hf;
> +	/* Enable the RSS hash in all Rx queues. */
> +	for (i = 0, idx = 0; idx != priv->rxqs_n; ++i) {
> +		if (!(*priv->rxqs)[i])
> +			continue;
> +		(*priv->rxqs)[i]->rss_hash = !!rss_conf->rss_hf &&
> +			!!(dev->data->dev_conf.rxmode.mq_mode & ETH_MQ_RX_RSS);
> +		++idx;
> +	}
>  	return 0;
>  }
>  
> diff --git a/drivers/net/mlx5/mlx5_rxq.c b/drivers/net/mlx5/mlx5_rxq.c
> index 56b2d19f2..1b4570586 100644
> --- a/drivers/net/mlx5/mlx5_rxq.c
> +++ b/drivers/net/mlx5/mlx5_rxq.c
> @@ -1070,7 +1070,8 @@ mlx5_rxq_new(struct rte_eth_dev *dev, uint16_t idx, uint16_t desc,
>  		tmpl->rxq.crc_present ? "disabled" : "enabled",
>  		tmpl->rxq.crc_present << 2);
>  	/* Save port ID. */
> -	tmpl->rxq.rss_hash = priv->rxqs_n > 1;
> +	tmpl->rxq.rss_hash = !!priv->rss_conf.rss_hf &&
> +		(!!(dev->data->dev_conf.rxmode.mq_mode & ETH_MQ_RX_RSS));
>  	tmpl->rxq.port_id = dev->data->port_id;
>  	tmpl->priv = priv;
>  	tmpl->rxq.mp = mp;
> -- 
> 2.11.0

I forgot to say that this patch applies on top of [1] and [2].

Regards,

[1] https://dpdk.org/browse/next/dpdk-next-net-mlx
[2] https://dpdk.org/dev/patchwork/patch/36066/

-- 
Nélio Laranjeiro
6WIND