[dpdk-dev] [PATCH] ethdev: add lock-less txq capability flag

[Jerin Jacob <jerin.jacob@caviumnetworks.com>]

if this flag is advertised by a PMD, Multiple threads can
invoke rte_eth_tx_burst() concurrently on the same tx queue
without SW lock. This is an HW feature found in some NICs
and useful in the following use cases if HW supports it.

1) Remove explicit spinlock in some application where cores
to tx queues are not mapped 1:1.
example: OVS has such instance
https://github.com/openvswitch/ovs/blob/master/lib/netdev-dpdk.c#L292
https://github.com/openvswitch/ovs/blob/master/lib/netdev-dpdk.c#L1821

2) In eventdev use case, Avoid dedicating a separate tx core
for transmit and thus enables more scaling as all workers
can transmit the packets.

Signed-off-by: Jerin Jacob <jerin.jacob@caviumnetworks.com>
---
 lib/librte_ether/rte_ethdev.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/lib/librte_ether/rte_ethdev.h b/lib/librte_ether/rte_ethdev.h
index f9de9a2b6..696bc9d44 100644
--- a/lib/librte_ether/rte_ethdev.h
+++ b/lib/librte_ether/rte_ethdev.h
@@ -899,6 +899,10 @@ struct rte_eth_conf {
 #define DEV_TX_OFFLOAD_IPIP_TNL_TSO     0x00000800    /**< Used for tunneling packet. */
 #define DEV_TX_OFFLOAD_GENEVE_TNL_TSO   0x00001000    /**< Used for tunneling packet. */
 #define DEV_TX_OFFLOAD_MACSEC_INSERT    0x00002000
+#define DEV_TX_OFFLOAD_TXQ_MT_LOCKFREE	0x00004000
+/**< Multiple threads can invoke rte_eth_tx_burst() concurrently on the same
+ * tx queue without SW lock.
+ */
 
 struct rte_pci_device;
 
-- 
2.12.2