[dpdk-dev] [PATCH v2 03/20] i40e: call i40e_txd_enable_checksum only for offloaded packets

Zhang, Helin helin.zhang at intel.com
Tue Feb 10 07:03:02 CET 2015



> -----Original Message-----
> From: Olivier Matz [mailto:olivier.matz at 6wind.com]
> Sent: Wednesday, February 4, 2015 5:25 PM
> To: dev at dpdk.org
> Cc: Ananyev, Konstantin; Liu, Jijiang; Zhang, Helin; olivier.matz at 6wind.com
> Subject: [PATCH v2 03/20] i40e: call i40e_txd_enable_checksum only for
> offloaded packets
> 
> From i40e datasheet:
> 
>   The IP header type and its offload. In case of tunneling, the IIPT
>   relates to the inner IP header. See also EIPT field for the outer
>   (External) IP header offload.
> 
>   00 - non IP packet or packet type is not defined by software
>   01 - IPv6 packet
>   10 - IPv4 packet with no IP checksum offload
>   11 - IPv4 packet with IP checksum offload
> 
> Therefore it is not needed to fill the IIPT field if no offload is requested (we can
> keep the value to 00). For instance, the linux driver code does not set it when
> (skb->ip_summed != CHECKSUM_PARTIAL). We can do the same in the dpdk
> driver.
> 
> The function i40e_txd_enable_checksum() that fills the offload registers can
> only be called for packets requiring an offload.
> 
> Signed-off-by: Olivier Matz <olivier.matz at 6wind.com>
> ---
>  lib/librte_pmd_i40e/i40e_rxtx.c | 15 +++++++++++----
>  1 file changed, 11 insertions(+), 4 deletions(-)
> 
> diff --git a/lib/librte_pmd_i40e/i40e_rxtx.c b/lib/librte_pmd_i40e/i40e_rxtx.c
> index 8e9df96..9acdeee 100644
> --- a/lib/librte_pmd_i40e/i40e_rxtx.c
> +++ b/lib/librte_pmd_i40e/i40e_rxtx.c
> @@ -74,6 +74,11 @@
> 
>  #define I40E_TXD_CMD (I40E_TX_DESC_CMD_EOP |
> I40E_TX_DESC_CMD_RS)
> 
> +#define I40E_TX_CKSUM_OFFLOAD_MASK (		 \
> +		PKT_TX_IP_CKSUM |		 \
> +		PKT_TX_L4_MASK |		 \
> +		PKT_TX_OUTER_IP_CKSUM)
> +
>  #define RTE_MBUF_DATA_DMA_ADDR_DEFAULT(mb) \
>  	(uint64_t) ((mb)->buf_physaddr + RTE_PKTMBUF_HEADROOM)
> 
> @@ -1272,10 +1277,12 @@ i40e_xmit_pkts(void *tx_queue, struct rte_mbuf
> **tx_pkts, uint16_t nb_pkts)
> 
>  		/* Enable checksum offloading */
>  		cd_tunneling_params = 0;
> -		i40e_txd_enable_checksum(ol_flags, &td_cmd, &td_offset,
> -						l2_len, l3_len, outer_l2_len,
> -						outer_l3_len,
> -						&cd_tunneling_params);
> +		if (ol_flags & I40E_TX_CKSUM_OFFLOAD_MASK) {
likely should be added.

> +			i40e_txd_enable_checksum(ol_flags, &td_cmd, &td_offset,
> +				l2_len, l3_len, outer_l2_len,
> +				outer_l3_len,
> +				&cd_tunneling_params);
> +		}
As this code changes are in fast path, performance regression test is needed. I would
like to see the performance difference with or without this patch set. Hopefully nothing
different. If you need any helps, just let me know.

Regards,
Helin

> 
>  		if (unlikely(nb_ctx)) {
>  			/* Setup TX context descriptor if required */
> --
> 2.1.4



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