Re: [dpdk-dev] [PATCH 2/3] net/i40e: add runtime option to disable vector rx

[Maxime Coquelin <maxime.coquelin@redhat.com>]

On 5/16/19 6:28 AM, Mesut Ali Ergin wrote:
> Vector RX functions are not at feature parity with non-vector ones and
> currently the vector RX path is enabled by default. Hence, the only
> option to force selection of non-vector variants and be able to retain
> functionality is to disable vector PMD globally at compile time via the
> config file option.
> 
> This patch introduces a new runtime device config option named
> disable-vec-rx to allow users to limit the driver to make a choice among
> non-vector RX functions, on a per device basis. This runtime option
> defaults to a value of zero, allowing vector RX functions to be
> selected (current behavior). When disable-vec-rx=1 is specified for a
> device, even if all the other requirements to select a vector RX
> function are satisfied, the driver will still pick one out of the
> appropriate non-vector RX functions.
> 
> Signed-off-by: Mesut Ali Ergin <mesut.a.ergin@intel.com>
> ---
>   doc/guides/nics/i40e.rst       | 14 +++++++++
>   drivers/net/i40e/i40e_ethdev.c | 70 +++++++++++++++++++++++++++++++++++++++++-
>   drivers/net/i40e/i40e_ethdev.h |  1 +
>   drivers/net/i40e/i40e_rxtx.c   |  4 +++
>   4 files changed, 88 insertions(+), 1 deletion(-)
> 
> diff --git a/doc/guides/nics/i40e.rst b/doc/guides/nics/i40e.rst
> index a97484c..532cc64 100644
> --- a/doc/guides/nics/i40e.rst
> +++ b/doc/guides/nics/i40e.rst
> @@ -183,6 +183,20 @@ Runtime Config Options
>   
>     -w 84:00.0,use-latest-supported-vec=1
>   
> +- ``Disable RX Vector Functions `` (default ``vector RX enabled``)
> +
> +  When config file option for the vector PMD is enabled, vector RX functions may
> +  be the default choice of the driver at device initialization time, if certain
> +  conditions apply. However, vector RX functions may not always be at feature
> +  parity with non-vector ones. In order to allow users to override vector RX
> +  function selection behavior at runtime, the ``devargs`` parameter
> +  ``disable-vec-rx`` is introduced, such that
> +
> +  -w DBDF,disable-vec-rx=1
> +
> +  would force driver to limit its choices to non-vector RX function variants for
> +  the device specified by the DBDF.
> +
>   Vector RX Pre-conditions
>   ~~~~~~~~~~~~~~~~~~~~~~~~
>   For Vector RX it is assumed that the number of descriptor rings will be a power
> diff --git a/drivers/net/i40e/i40e_ethdev.c b/drivers/net/i40e/i40e_ethdev.c
> index cab440f..19fbd23 100644
> --- a/drivers/net/i40e/i40e_ethdev.c
> +++ b/drivers/net/i40e/i40e_ethdev.c
> @@ -44,6 +44,7 @@
>   #define ETH_I40E_SUPPORT_MULTI_DRIVER	"support-multi-driver"
>   #define ETH_I40E_QUEUE_NUM_PER_VF_ARG	"queue-num-per-vf"
>   #define ETH_I40E_USE_LATEST_VEC	"use-latest-supported-vec"
> +#define ETH_I40E_DISABLE_VEC_RX	"disable-vec-rx"
>   
>   #define I40E_CLEAR_PXE_WAIT_MS     200
>   
> @@ -410,6 +411,7 @@ static const char *const valid_keys[] = {
>   	ETH_I40E_SUPPORT_MULTI_DRIVER,
>   	ETH_I40E_QUEUE_NUM_PER_VF_ARG,
>   	ETH_I40E_USE_LATEST_VEC,
> +	ETH_I40E_DISABLE_VEC_RX,
>   	NULL};
>   
>   static const struct rte_pci_id pci_id_i40e_map[] = {
> @@ -1263,6 +1265,68 @@ i40e_use_latest_vec(struct rte_eth_dev *dev)
>   	return 0;
>   }
>   
> +static int
> +i40e_parse_disable_vec_rx_handler(__rte_unused const char *key,
> +				const char *value,
> +				void *opaque)
> +{
> +	struct i40e_adapter *ad;
> +
> +	ad = (struct i40e_adapter *)opaque;
> +
> +	switch (atoi(value)) {
> +	case 0:
> +		/* Selection of RX vector functions left untouched*/
> +		break;
> +	case 1:
> +		/* Disable RX vector functions as requested*/
> +		ad->rx_vec_allowed = false;
> +	break;
> +	default:
> +		PMD_DRV_LOG(WARNING, "Value should be 0 or 1, set it as 1!");

You may want to propagate the error here.

> +	break;
> +	}
> +
> +	return 0;
> +}
> +
> +int
> +i40e_disable_vec_rx(struct rte_eth_dev *dev)
> +{
> +	struct i40e_adapter *ad =
> +		I40E_DEV_PRIVATE_TO_ADAPTER(dev->data->dev_private);
> +	struct rte_kvargs *kvlist;
> +	int kvargs_count;
> +
> +
> +	if (!dev->device->devargs)
> +		return 0;
> +
> +	kvlist = rte_kvargs_parse(dev->device->devargs->args, valid_keys);
> +	if (!kvlist)
> +		return -EINVAL;
> +
> +	kvargs_count = rte_kvargs_count(kvlist, ETH_I40E_DISABLE_VEC_RX);
> +	if (!kvargs_count) {
> +		rte_kvargs_free(kvlist);
> +		return 0;
> +	}
> +
> +	if (kvargs_count > 1)
> +		PMD_DRV_LOG(WARNING, "More than one argument \"%s\" and only "
> +			    "the first invalid or last valid one is used !",
> +			    ETH_I40E_DISABLE_VEC_RX);
> +
> +	if (rte_kvargs_process(kvlist, ETH_I40E_DISABLE_VEC_RX,
> +				i40e_parse_disable_vec_rx_handler, ad) < 0) {
> +		rte_kvargs_free(kvlist);
> +		return -EINVAL;
> +	}
> +
> +	rte_kvargs_free(kvlist);
> +	return 0;
> +}
> +
>   #define I40E_ALARM_INTERVAL 50000 /* us */
>   
>   static int
> @@ -1795,6 +1859,9 @@ i40e_dev_configure(struct rte_eth_dev *dev)
>   	ad->tx_simple_allowed = true;
>   	ad->tx_vec_allowed = true;
>   
> +	/* Check if users wanted to disable vector RX functions */
> +	i40e_disable_vec_rx(dev);

Ditto, error should be propagated.

> +
>   	/* Only legacy filter API needs the following fdir config. So when the
>   	 * legacy filter API is deprecated, the following codes should also be
>   	 * removed.
> @@ -12790,4 +12857,5 @@ RTE_PMD_REGISTER_PARAM_STRING(net_i40e,
>   			      ETH_I40E_FLOATING_VEB_LIST_ARG "=<string>"
>   			      ETH_I40E_QUEUE_NUM_PER_VF_ARG "=1|2|4|8|16"
>   			      ETH_I40E_SUPPORT_MULTI_DRIVER "=1"
> -			      ETH_I40E_USE_LATEST_VEC "=0|1");
> +			      ETH_I40E_USE_LATEST_VEC "=0|1"
> +			      ETH_I40E_DISABLE_VEC_RX "=0|1");
> diff --git a/drivers/net/i40e/i40e_ethdev.h b/drivers/net/i40e/i40e_ethdev.h
> index 9855038..906bfe9 100644
> --- a/drivers/net/i40e/i40e_ethdev.h
> +++ b/drivers/net/i40e/i40e_ethdev.h
> @@ -1248,6 +1248,7 @@ int i40e_config_rss_filter(struct i40e_pf *pf,
>   		struct i40e_rte_flow_rss_conf *conf, bool add);
>   int i40e_vf_representor_init(struct rte_eth_dev *ethdev, void *init_params);
>   int i40e_vf_representor_uninit(struct rte_eth_dev *ethdev);
> +int i40e_disable_vec_rx(struct rte_eth_dev *dev);
>   
>   #define I40E_DEV_TO_PCI(eth_dev) \
>   	RTE_DEV_TO_PCI((eth_dev)->device)
> diff --git a/drivers/net/i40e/i40e_rxtx.c b/drivers/net/i40e/i40e_rxtx.c
> index 1489552..7e66f59 100644
> --- a/drivers/net/i40e/i40e_rxtx.c
> +++ b/drivers/net/i40e/i40e_rxtx.c
> @@ -1736,6 +1736,10 @@ i40e_dev_rx_queue_setup_runtime(struct rte_eth_dev *dev,
>   		 */
>   		ad->rx_bulk_alloc_allowed = true;
>   		ad->rx_vec_allowed = true;
> +
> +		/* Check if users wanted to disable vector RX functions */
> +		i40e_disable_vec_rx(dev);
> +

Ditto, error should be propagated.

>   		dev->data->scattered_rx = use_scattered_rx;
>   		if (use_def_burst_func)
>   			ad->rx_bulk_alloc_allowed = false;
>