Re: [dpdk-dev] [PATCH v2 5/6] net/af_xdp: enable zero copy

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

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Hi, Mattias

Thanks for the review.

On 03/19, Mattias Rönnblom wrote:
>On 2019-03-19 08:12, 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 | 128 ++++++++++++++++++++--------
>>   1 file changed, 91 insertions(+), 37 deletions(-)
>> 
>> diff --git a/drivers/net/af_xdp/rte_eth_af_xdp.c b/drivers/net/af_xdp/rte_eth_af_xdp.c
>> index fc60cb5c5..c22791e51 100644
>> --- a/drivers/net/af_xdp/rte_eth_af_xdp.c
>> +++ b/drivers/net/af_xdp/rte_eth_af_xdp.c
>> @@ -62,6 +62,7 @@ struct xsk_umem_info {
>>   	struct xsk_umem *umem;
>>   	struct rte_mempool *mb_pool;
>>   	void *buffer;
>> +	uint8_t zc;
>>   };
>>   struct pkt_rx_queue {
>> @@ -76,6 +77,7 @@ struct pkt_rx_queue {
>>   	struct pkt_tx_queue *pair;
>>   	uint16_t queue_idx;
>> +	uint8_t zc;
>>   };
>>   struct pkt_tx_queue {
>> @@ -191,17 +193,24 @@ eth_af_xdp_rx(void *queue, struct rte_mbuf **bufs, uint16_t nb_pkts)
>>   		uint32_t len = xsk_ring_cons__rx_desc(rx, idx_rx++)->len;
>>   		char *pkt = xsk_umem__get_data(rxq->umem->buffer, addr);
>> -		mbuf = rte_pktmbuf_alloc(rxq->mb_pool);
>> -		if (mbuf) {
>> -			memcpy(rte_pktmbuf_mtod(mbuf, void*), pkt, len);
>> +		if (rxq->zc) {
>> +			mbuf = addr_to_mbuf(rxq->umem, addr);
>>   			rte_pktmbuf_pkt_len(mbuf) =
>>   				rte_pktmbuf_data_len(mbuf) = len;
>> -			rx_bytes += len;
>>   			bufs[count++] = mbuf;
>>   		} else {
>> -			dropped++;
>> +			mbuf = rte_pktmbuf_alloc(rxq->mb_pool);
>> +			if (mbuf) {
>
>if (likely(mbuf != NULL))

Got it.

>
>> +				memcpy(rte_pktmbuf_mtod(mbuf, void*), pkt, len);
>
>Use rte_memcpy.

Got it.

>
>> +				rte_pktmbuf_pkt_len(mbuf) =
>> +					rte_pktmbuf_data_len(mbuf) = len;
>> +				rx_bytes += len;
>> +				bufs[count++] = mbuf;
>> +			} else {
>> +				dropped++;
>> +			}
>> +			rte_pktmbuf_free(addr_to_mbuf(umem, addr));
>>   		}
>> -		rte_pktmbuf_free(addr_to_mbuf(umem, addr));
>>   	}
>>   	xsk_ring_cons__release(rx, rcvd);
>> @@ -285,22 +294,29 @@ eth_af_xdp_tx(void *queue, struct rte_mbuf **bufs, uint16_t nb_pkts)
>>   					- ETH_AF_XDP_DATA_HEADROOM;
>>   		desc = xsk_ring_prod__tx_desc(&txq->tx, idx_tx + i);
>>   		mbuf = bufs[i];
>> -		if (mbuf->pkt_len <= buf_len) {
>> -			mbuf_to_tx = rte_pktmbuf_alloc(umem->mb_pool);
>> -			if (!mbuf_to_tx) {
>> -				rte_pktmbuf_free(mbuf);
>> -				continue;
>> -			}
>> -			desc->addr = mbuf_to_addr(umem, mbuf_to_tx);
>> +		if (txq->pair->zc && mbuf->pool == umem->mb_pool) {
>> +			desc->addr = mbuf_to_addr(umem, mbuf);
>>   			desc->len = mbuf->pkt_len;
>> -			pkt = xsk_umem__get_data(umem->buffer,
>> -						 desc->addr);
>> -			memcpy(pkt, rte_pktmbuf_mtod(mbuf, void *),
>> -			       desc->len);
>>   			valid++;
>>   			tx_bytes += mbuf->pkt_len;
>> +		} else {
>> +			if (mbuf->pkt_len <= buf_len) {
>> +				mbuf_to_tx = rte_pktmbuf_alloc(umem->mb_pool);
>> +				if (!mbuf_to_tx) {
>
>if (unlikely(mbuf_to_tx == NULL))
>
>See DPDK coding conventions 1.8.1 for how to do pointer comparisons.

I'll check it and do it correctly in next version.

>
>> +					rte_pktmbuf_free(mbuf);
>> +					continue;
>> +				}
>> +				desc->addr = mbuf_to_addr(umem, mbuf_to_tx);
>> +				desc->len = mbuf->pkt_len;
>> +				pkt = xsk_umem__get_data(umem->buffer,
>> +							 desc->addr);
>> +				memcpy(pkt, rte_pktmbuf_mtod(mbuf, void *),
>> +				       desc->len);
>
>rte_memcpy()

Got it.

>
>> +				valid++;
>> +				tx_bytes += mbuf->pkt_len;
>> +			}
>> +			rte_pktmbuf_free(mbuf);
>>   		}
>> -		rte_pktmbuf_free(mbuf);
>>   	}
>>   	xsk_ring_prod__submit(&txq->tx, nb_pkts);
>> @@ -479,7 +495,7 @@ static inline uint64_t get_len(struct rte_mempool *mp)
>>   	return (uint64_t)(memhdr->len);
>>   }
>> -static struct xsk_umem_info *xdp_umem_configure(void)
>> +static struct xsk_umem_info *xdp_umem_configure(struct rte_mempool *mb_pool)
>>   {
>>   	struct xsk_umem_info *umem;
>>   	struct xsk_umem_config usr_config = {
>> @@ -497,20 +513,25 @@ static struct xsk_umem_info *xdp_umem_configure(void)
>>   		return NULL;
>>   	}
>> -	snprintf(pool_name, 0x100, "af_xdp_ring");
>> -	umem->mb_pool = rte_pktmbuf_pool_create_with_flags(pool_name,
>> -			ETH_AF_XDP_NUM_BUFFERS,
>> -			250, 0,
>> -			ETH_AF_XDP_FRAME_SIZE -
>> -			ETH_AF_XDP_MBUF_OVERHEAD,
>> -			MEMPOOL_F_NO_SPREAD | MEMPOOL_F_PAGE_ALIGN,
>> -			SOCKET_ID_ANY);
>> -
>> -	if (!umem->mb_pool || umem->mb_pool->nb_mem_chunks != 1) {
>> -		RTE_LOG(ERR, AF_XDP,
>> -			"Failed to create rte_mempool\n");
>> -		goto err;
>> +	if (!mb_pool) {
>
>1.8.1

Got it.

>
>> +		snprintf(pool_name, 0x100, "af_xdp_ring");
>
>0x100??

Will use RTE_MEMPOOL_NAMESIZE instead.

>
>> +		umem->mb_pool = rte_pktmbuf_pool_create_with_flags(pool_name,
>> +				ETH_AF_XDP_NUM_BUFFERS,
>> +				250, 0,
>> +				ETH_AF_XDP_FRAME_SIZE -
>> +				ETH_AF_XDP_MBUF_OVERHEAD,
>> +				MEMPOOL_F_NO_SPREAD | MEMPOOL_F_PAGE_ALIGN,
>> +				SOCKET_ID_ANY);
>> +
>> +		if (!umem->mb_pool || umem->mb_pool->nb_mem_chunks != 1) {
>
>1.8.1

Got it.

>
>> +			RTE_LOG(ERR, AF_XDP, "Failed to create rte_mempool\n");
>> +			goto err;
>> +		}
>> +	} else {
>> +		umem->mb_pool = mb_pool;
>> +		umem->zc = 1;
>>   	}
>> +
>>   	base_addr = (void *)get_base_addr(umem->mb_pool);
>>   	ret = xsk_umem__create(&umem->umem, base_addr,
>> @@ -531,16 +552,43 @@ static struct xsk_umem_info *xdp_umem_configure(void)
>>   	return NULL;
>>   }
>> +static uint8_t
>> +check_mempool_zc(struct rte_mempool *mp)
>> +{
>> +	RTE_ASSERT(mp);
>> +
>> +	/* must continues */
>> +	if (mp->nb_mem_chunks > 1)
>> +		return 0;
>> +
>> +	/* check header size */
>> +	if (mp->header_size != RTE_CACHE_LINE_SIZE)
>> +		return 0;
>> +
>> +	/* check base address */
>> +	if ((uint64_t)get_base_addr(mp) % getpagesize() != 0)
>
>This should be an uintptr_t cast.

Got it.

Thanks,
Xiaolong
>
>> +		return 0;
>> +
>> +	/* check chunk size */
>> +	if ((mp->elt_size + mp->header_size + mp->trailer_size) %
>> +	    ETH_AF_XDP_FRAME_SIZE != 0)
>> +		return 0;
>> +
>> +	return 1;
>> +}
>> +
>>   static int
>>   xsk_configure(struct pmd_internals *internals, struct pkt_rx_queue *rxq,
>> -	      int ring_size)
>> +	      int ring_size, struct rte_mempool *mb_pool)
>>   {
>>   	struct xsk_socket_config cfg;
>>   	struct pkt_tx_queue *txq = rxq->pair;
>> +	struct rte_mempool *mp;
>>   	int ret = 0;
>>   	int reserve_size;
>> -	rxq->umem = xdp_umem_configure();
>> +	mp = check_mempool_zc(mb_pool) ? mb_pool : NULL;
>> +	rxq->umem = xdp_umem_configure(mp);
>>   	if (!rxq->umem) {
>>   		ret = -ENOMEM;
>>   		goto err;
>> @@ -627,15 +675,21 @@ eth_rx_queue_setup(struct rte_eth_dev *dev,
>>   	rxq->mb_pool = mb_pool;
>> -	if (xsk_configure(internals, rxq, nb_rx_desc)) {
>> -		RTE_LOG(ERR, AF_XDP,
>> -			"Failed to configure xdp socket\n");
>> +	if (xsk_configure(internals, rxq, nb_rx_desc, mb_pool)) {
>> +		RTE_LOG(ERR, AF_XDP, "Failed to configure xdp socket\n");
>>   		ret = -EINVAL;
>>   		goto err;
>>   	}
>>   	internals->umem = rxq->umem;
>> +	if (mb_pool == internals->umem->mb_pool)
>> +		rxq->zc = internals->umem->zc;
>> +
>> +	if (rxq->zc)
>> +		RTE_LOG(INFO, AF_XDP,
>> +			"zero copy enabled on rx queue %d\n", rx_queue_id);
>> +
>>   	dev->data->rx_queues[rx_queue_id] = rxq;
>>   	return 0;
>>