Re: [dpdk-dev] [PATCH v7 5/5] net/af_xdp: enable zero copy

[Ye Xiaolong <xiaolong.ye@intel.com>]

On 03/28, Ferruh Yigit wrote:
>On 3/27/2019 9:00 AM, Xiaolong Ye wrote:
>> Try to check if external mempool (from rx_queue_setup) is fit for
>> af_xdp, if it is, it will be registered to af_xdp socket directly and
>> there will be no packet data copy on Rx and Tx.
>> 
>> Signed-off-by: Xiaolong Ye <xiaolong.ye@intel.com>
>> ---
>>  drivers/net/af_xdp/rte_eth_af_xdp.c | 130 ++++++++++++++++++++--------
>>  1 file changed, 96 insertions(+), 34 deletions(-)
>> 
>> diff --git a/drivers/net/af_xdp/rte_eth_af_xdp.c b/drivers/net/af_xdp/rte_eth_af_xdp.c
>> index a1fda9212..c6ade4c94 100644
>> --- a/drivers/net/af_xdp/rte_eth_af_xdp.c
>> +++ b/drivers/net/af_xdp/rte_eth_af_xdp.c
>> @@ -67,6 +67,7 @@ struct xsk_umem_info {
>>  	struct xsk_umem *umem;
>>  	struct rte_mempool *mb_pool;
>>  	void *buffer;
>> +	uint8_t zc;
>>  };
>>  
>>  struct rx_stats {
>> @@ -85,6 +86,7 @@ struct pkt_rx_queue {
>>  
>>  	struct pkt_tx_queue *pair;
>>  	uint16_t queue_idx;
>> +	uint8_t zc;
>>  };
>>  
>>  struct tx_stats {
>
><...>
>
>> @@ -630,6 +685,13 @@ eth_rx_queue_setup(struct rte_eth_dev *dev,
>>  
>>  	internals->umem = rxq->umem;
>>  
>> +	if (mb_pool == internals->umem->mb_pool)
>> +		rxq->zc = internals->umem->zc;
>> +
>> +	if (rxq->zc)
>> +		AF_XDP_LOG(INFO,
>> +			"zero copy enabled on rx queue %d\n", rx_queue_id);
>> +
>
>The "zero copy" implemented in this patch, also the variable 'zc', is from
>'af_xdp' umem to mbuf data via versa copy, right?
>There is also another "zero copy" support in af_xdp, device to buffers...
>Do you think can these be confused with each other, should we have another log
>message and variable name for this one?
>Indeed I can't think of a good name, but something like, "pmd/driver zero copy"
>& 'pmd_zc' ??

That's a good suggestion, will adopt it.

Thanks,
Xiaolong