Re: [dpdk-stable] patch 'net/i40e: fix Rx instability with vector mode' has been queued to stable release 18.08.1

[Kevin Traynor <ktraynor@redhat.com>]

On 11/29/2018 01:20 PM, Kevin Traynor wrote:
> Hi,
> 
> FYI, your patch has been queued to stable release 18.08.1
> 
> Note it hasn't been pushed to http://dpdk.org/browse/dpdk-stable yet.
> It will be pushed if I get no objections before 12/08/18. So please
> shout if anyone has objections.
> 
> Also note that after the patch there's a diff of the upstream commit vs the patch applied
> to the branch. If the code is different (ie: not only metadata diffs), due for example to
> a change in context or macro names, please double check it.
> 

Hi, this is a resend to stable - previous version had a conflict in the
docs because of context.

> Thanks.
> 
> Kevin Traynor
> 
> ---
> From 710f8e2bcf60798ad1d7236d2609a50491c599a4 Mon Sep 17 00:00:00 2001
> From: Beilei Xing <beilei.xing@intel.com>
> Date: Mon, 5 Nov 2018 11:18:12 +0800
> Subject: [PATCH] net/i40e: fix Rx instability with vector mode
> 
> [ upstream commit 054d1be48cc114c5d3bf87c7ebdf46703876e8d5 ]
> 
> Previously, there is instability during vector Rx if descriptor
> number is not power of 2, e.g. process hang and some Rx packets
> are unexpectedly empty. That's because vector Rx mode assumes Rx
> descriptor number is power of 2 when doing bit mask.
> This patch allows vector mode only when the number of Rx descriptor
> is power of 2.
> 
> Fixes: 8e109464c022 ("i40e: allow vector Rx and Tx usage")
> Fixes: a3c83a2527e1 ("net/i40e: enable runtime queue setup")
> 
> Signed-off-by: Beilei Xing <beilei.xing@intel.com>
> Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>
> ---
>  doc/guides/nics/i40e.rst                |  7 +++++
>  drivers/net/i40e/i40e_rxtx.c            |  5 ++++
>  drivers/net/i40e/i40e_rxtx_vec_common.h | 38 +++++++++++++++++++++++++
>  3 files changed, 50 insertions(+)
> 
> diff --git a/doc/guides/nics/i40e.rst b/doc/guides/nics/i40e.rst
> index 65d87f869..643756dcd 100644
> --- a/doc/guides/nics/i40e.rst
> +++ b/doc/guides/nics/i40e.rst
> @@ -164,4 +164,11 @@ Runtime Config Options
>    representors must be specified on the creation of the PF.
>  
> +Vector RX Pre-conditions
> +~~~~~~~~~~~~~~~~~~~~~~~~
> +For Vector RX it is assumed that the number of descriptor rings will be a power
> +of 2. With this pre-condition, the ring pointer can easily scroll back to the
> +head after hitting the tail without a conditional check. In addition Vector RX
> +can use this assumption to do a bit mask using ``ring_size - 1``.
> +
>  Driver compilation and testing
>  ------------------------------
> diff --git a/drivers/net/i40e/i40e_rxtx.c b/drivers/net/i40e/i40e_rxtx.c
> index 26c2f17bd..e0d53d022 100644
> --- a/drivers/net/i40e/i40e_rxtx.c
> +++ b/drivers/net/i40e/i40e_rxtx.c
> @@ -1741,4 +1741,9 @@ i40e_dev_rx_queue_setup_runtime(struct rte_eth_dev *dev,
>  		i40e_set_rx_function(dev);
>  		return 0;
> +	} else if (ad->rx_vec_allowed && !rte_is_power_of_2(rxq->nb_rx_desc)) {
> +		PMD_DRV_LOG(ERR, "Vector mode is allowed, but descriptor"
> +			    " number %d of queue %d isn't power of 2",
> +			    rxq->nb_rx_desc, rxq->queue_id);
> +		return -EINVAL;
>  	}
>  
> diff --git a/drivers/net/i40e/i40e_rxtx_vec_common.h b/drivers/net/i40e/i40e_rxtx_vec_common.h
> index 63cb17742..ccaffef99 100644
> --- a/drivers/net/i40e/i40e_rxtx_vec_common.h
> +++ b/drivers/net/i40e/i40e_rxtx_vec_common.h
> @@ -193,6 +193,11 @@ i40e_rx_vec_dev_conf_condition_check_default(struct rte_eth_dev *dev)
>  {
>  #ifndef RTE_LIBRTE_IEEE1588
> +	struct i40e_adapter *ad =
> +		I40E_DEV_PRIVATE_TO_ADAPTER(dev->data->dev_private);
>  	struct rte_eth_rxmode *rxmode = &dev->data->dev_conf.rxmode;
>  	struct rte_fdir_conf *fconf = &dev->data->dev_conf.fdir_conf;
> +	struct i40e_rx_queue *rxq;
> +	uint16_t desc, i;
> +	bool first_queue;
>  
>  	/* no fdir support */
> @@ -210,4 +215,37 @@ i40e_rx_vec_dev_conf_condition_check_default(struct rte_eth_dev *dev)
>  		return -1;
>  
> +	/**
> +	 * Vector mode is allowed only when number of Rx queue
> +	 * descriptor is power of 2.
> +	 */
> +	if (!dev->data->dev_started) {
> +		first_queue = true;
> +		for (i = 0; i < dev->data->nb_rx_queues; i++) {
> +			rxq = dev->data->rx_queues[i];
> +			if (!rxq)
> +				continue;
> +			desc = rxq->nb_rx_desc;
> +			if (first_queue)
> +				ad->rx_vec_allowed =
> +					rte_is_power_of_2(desc);
> +			else
> +				ad->rx_vec_allowed =
> +					ad->rx_vec_allowed ?
> +					rte_is_power_of_2(desc) :
> +					ad->rx_vec_allowed;
> +			first_queue = false;
> +		}
> +	} else {
> +		/* Only check the first queue's descriptor number */
> +		for (i = 0; i < dev->data->nb_rx_queues; i++) {
> +			rxq = dev->data->rx_queues[i];
> +			if (!rxq)
> +				continue;
> +			desc = rxq->nb_rx_desc;
> +			ad->rx_vec_allowed = rte_is_power_of_2(desc);
> +			break;
> +		}
> +	}
> +
>  	return 0;
>  #else
>