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

[Mesut Ali Ergin]

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 at 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!");
+	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);
+
 	/* 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);
+
 		dev->data->scattered_rx = use_scattered_rx;
 		if (use_def_burst_func)
 			ad->rx_bulk_alloc_allowed = false;
-- 
2.7.4