[dpdk-dev] [PATCH] eal: added new api to only enqueue a packet in tx buffer

[Ferruh Yigit]

On 10/18/2019 5:24 PM, Yigit, Ferruh wrote:
> On 8/8/2019 1:28 PM, Nilanjan Sarkar wrote:
>> This api is similar like api `rte_eth_tx_buffer` except it
>> does not attempt to flush the buffer in case buffer is full.
>> The advantage is that, this api does not need port id and
>> queue id. In case port id and queue id are shared within threads
>> then application can not buffer a packet until it gets access
>> to port and queue. So this function segregate buffering
>> job from flushing job and thus removes dependency on port and queue.
> 
> Hi Nilanjan,
> 
> Sorry, the patch seems missed because of the misleading module info in the patch
> title, this is not an 'eal' patch but a 'ethdev' patch ...
> 
> Related to the API, it looks like target is to reduce the critical section which
> looks reasonable to me.
> 
> A concern is related to the making this function inline, we are discussing
> moving existing inline functions to regular functions, this may have performance
> affect but if the drop is acceptable what about making this an ethdev API?
> 

There was no response on making the new proposed API a proper function.

@Thomas, @Andrew, et al,

What do you think about a new static inline ethdev API?

> 
>>
>> Signed-off-by: Nilanjan Sarkar <nsarkar at sandvine.com>
>> ---
>>  lib/librte_ethdev/rte_ethdev.h | 29 +++++++++++++++++++++++++++++
>>  1 file changed, 29 insertions(+)
>>
>> diff --git a/lib/librte_ethdev/rte_ethdev.h b/lib/librte_ethdev/rte_ethdev.h
>> index dc6596bc9..bd8b8fee4 100644
>> --- a/lib/librte_ethdev/rte_ethdev.h
>> +++ b/lib/librte_ethdev/rte_ethdev.h
>> @@ -4569,6 +4569,35 @@ rte_eth_tx_buffer(uint16_t port_id, uint16_t queue_id,
>>  	return rte_eth_tx_buffer_flush(port_id, queue_id, buffer);
>>  }
>>  
>> +/**
>> + * Buffer a single packet for future transmission on Tx buffer. This buffer
>> + * can be sent to a port and queue of a NIC using rte_eth_tx_buffer_flush ()
>> + * call.
>> + *
>> + * This function enqueues a packet to Tx buffer. In case there is no space
>> + * in Tx buffer, this function fails.
>> + * Tx buffer will be flushed using rte_eth_tx_buffer_flush () call. It is
>> + * application's responsibility to flush the Tx buffer in regular interval.
>> + *
>> + * @param buffer
>> + *  Buffer used to collect packets to be sent.
>> + * @param tx_pkt
>> + *  Pointer to the packet mbuf to be sent.
>> + * @return
>> + *  0 = packet has been buffered for later transmission
>> + *  -1 = Packet can not be buffered since it reached limit
>> + */
>> +static __rte_always_inline int
>> +rte_eth_tx_enqueue(struct rte_eth_dev_tx_buffer *buffer, struct rte_mbuf *tx_pkt)
>> +{
>> +	if (buffer->length < buffer->size) {
>> +		buffer->pkts[buffer->length++] = tx_pkt;
>> +		return 0;
>> +	}
>> +
>> +	return -1;
>> +}
>> +
>>  #ifdef __cplusplus
>>  }
>>  #endif
>>
>