Re: [dpdk-dev] [PATCH v4 1/2] e1000: enable igb TSO support

["Wang, Xiao W" <xiao.w.wang@intel.com>]

Hi, Helin

	Thanks a lot for your comments, please find my reply inline.

> -----Original Message-----
> From: Zhang, Helin
> Sent: Friday, October 23, 2015 10:04 AM
> To: Wang, Xiao W; dev@dpdk.org
> Cc: Lu, Wenzhuo; Richardson, Bruce
> Subject: RE: [PATCH v4 1/2] e1000: enable igb TSO support
> 
> 
> 
> > -----Original Message-----
> > From: Wang, Xiao W
> > Sent: Wednesday, October 21, 2015 3:55 PM
> > To: dev@dpdk.org
> > Cc: Lu, Wenzhuo; Richardson, Bruce; Zhang, Helin; Wang, Xiao W
> > Subject: [PATCH v4 1/2] e1000: enable igb TSO support
> >
> > This patch enables igb TSO feature, the feature works on both PF and VF.
> > The TCP segmentation offload needs to write the offload related
> > information into the advanced context descriptors, which is similar to
> checksum offload.
> >
> > Signed-off-by: Wang Xiao W <xiao.w.wang@intel.com>
> > ---
> >  drivers/net/e1000/igb_ethdev.c |   6 +-
> >  drivers/net/e1000/igb_rxtx.c   | 200
> > +++++++++++++++++++++++++----------------
> >  2 files changed, 127 insertions(+), 79 deletions(-)
> >
> > diff --git a/drivers/net/e1000/igb_ethdev.c
> > b/drivers/net/e1000/igb_ethdev.c index 848ef6e..2e69394 100644
> > --- a/drivers/net/e1000/igb_ethdev.c
> > +++ b/drivers/net/e1000/igb_ethdev.c
> > @@ -1497,7 +1497,8 @@ eth_igb_infos_get(struct rte_eth_dev *dev,
> > struct rte_eth_dev_info *dev_info)
> >  		DEV_TX_OFFLOAD_IPV4_CKSUM  |
> >  		DEV_TX_OFFLOAD_UDP_CKSUM   |
> >  		DEV_TX_OFFLOAD_TCP_CKSUM   |
> > -		DEV_TX_OFFLOAD_SCTP_CKSUM;
> > +		DEV_TX_OFFLOAD_SCTP_CKSUM  |
> > +		DEV_TX_OFFLOAD_TCP_TSO;
> >
> >  	switch (hw->mac.type) {
> >  	case e1000_82575:
> > @@ -1588,7 +1589,8 @@ eth_igbvf_infos_get(struct rte_eth_dev *dev,
> > struct rte_eth_dev_info *dev_info)
> >  				DEV_TX_OFFLOAD_IPV4_CKSUM  |
> >  				DEV_TX_OFFLOAD_UDP_CKSUM   |
> >  				DEV_TX_OFFLOAD_TCP_CKSUM   |
> > -				DEV_TX_OFFLOAD_SCTP_CKSUM;
> > +				DEV_TX_OFFLOAD_SCTP_CKSUM  |
> > +				DEV_TX_OFFLOAD_TCP_TSO;
> >  	switch (hw->mac.type) {
> >  	case e1000_vfadapt:
> >  		dev_info->max_rx_queues = 2;
> > diff --git a/drivers/net/e1000/igb_rxtx.c
> > b/drivers/net/e1000/igb_rxtx.c index
> > 19905fd..2b8a1c8 100644
> > --- a/drivers/net/e1000/igb_rxtx.c
> > +++ b/drivers/net/e1000/igb_rxtx.c
> > @@ -76,7 +76,8 @@
> >  #define IGB_TX_OFFLOAD_MASK (			 \
> >  		PKT_TX_VLAN_PKT |		 \
> >  		PKT_TX_IP_CKSUM |		 \
> > -		PKT_TX_L4_MASK)
> > +		PKT_TX_L4_MASK |		 \
> > +		PKT_TX_TCP_SEG)
> >
> >  static inline struct rte_mbuf *
> >  rte_rxmbuf_alloc(struct rte_mempool *mp) @@ -146,32 +147,40 @@
> enum
> > igb_advctx_num {  };
> >
> >  /** Offload features */
> > -union igb_vlan_macip {
> > -	uint32_t data;
> > +union igb_tx_offload {
> > +	uint64_t data;
> Adding previous definition back to this union is helpful of using the first 16
> bits and second 16 bits?
> Of cause, the newly added struct should be kept as is.
> 	struct {
> 		uint16_t l2_l3_len;
> 		uint16_t vlan_tci;
> 		uint16_t l4_tso_len;
> 		uint16_t others;
> 	};

In the patch, we need to quote the l3_len and l2_len separately for some times, for example "tx_offload.l3_len = tx_pkt->l3_len;" 
It's more convenient to define them separately.

> >  	struct {
> > -		uint16_t l2_l3_len; /**< 7bit L2 and 9b L3 lengths combined
> */
> > -		uint16_t vlan_tci;
> > -		/**< VLAN Tag Control Identifier (CPU order). */
> > -	} f;
> > +		uint64_t l3_len:9; /**< L3 (IP) Header Length. */
> > +		uint64_t l2_len:7; /**< L2 (MAC) Header Length. */
> > +		uint64_t vlan_tci:16;  /**< VLAN Tag Control Identifier(CPU
> order). */
> > +		uint64_t l4_len:8; /**< L4 (TCP/UDP) Header Length. */
> > +		uint64_t tso_segsz:16; /**< TCP TSO segment size. */
> > +
> > +		/* uint64_t unused:8; */
> > +	};
> >  };
> >
> >  /*
> > - * Compare mask for vlan_macip_len.data,
> > - * should be in sync with igb_vlan_macip.f layout.
> > + * Compare mask for igb_tx_offload.data,
> > + * should be in sync with igb_tx_offload layout.
> >   * */
> > -#define TX_VLAN_CMP_MASK        0xFFFF0000  /**< VLAN length -
> > 16-bits. */
> > -#define TX_MAC_LEN_CMP_MASK     0x0000FE00  /**< MAC length - 7-
> bits.
> > */
> > -#define TX_IP_LEN_CMP_MASK      0x000001FF  /**< IP  length - 9-bits. */
> > -/** MAC+IP  length. */
> > -#define TX_MACIP_LEN_CMP_MASK   (TX_MAC_LEN_CMP_MASK |
> > TX_IP_LEN_CMP_MASK)
> > +#define TX_MACIP_LEN_CMP_MASK	0x000000000000FFFFULL /**<
> L2L3
> > header mask. */
> > +#define TX_VLAN_CMP_MASK		0x00000000FFFF0000ULL /**<
> Vlan mask.
> > */
> > +#define TX_TCP_LEN_CMP_MASK		0x000000FF00000000ULL /**<
> TCP
> > header mask. */
> > +#define TX_TSO_MSS_CMP_MASK		0x00FFFF0000000000ULL /**<
> TSO
> > segsz mask. */
> > +/** Mac + IP + TCP + Mss mask. */
> > +#define TX_TSO_CMP_MASK	\
> > +	(TX_MACIP_LEN_CMP_MASK | TX_TCP_LEN_CMP_MASK |
> > TX_TSO_MSS_CMP_MASK)
> >
> >  /**
> >   * Strucutre to check if new context need be built
> >   */
> >  struct igb_advctx_info {
> >  	uint64_t flags;           /**< ol_flags related to context build. */
> > -	uint32_t cmp_mask;        /**< compare mask for vlan_macip_lens */
> > -	union igb_vlan_macip vlan_macip_lens; /**< vlan, mac & ip length.
> */
> > +	/** tx offload: vlan, tso, l2-l3-l4 lengths. */
> > +	union igb_tx_offload tx_offload;
> > +	/** compare mask for tx offload. */
> > +	union igb_tx_offload tx_offload_mask;
> Would above mask be better/clearer replaced by uint64_t directly?
> You can think a bit, I am not quite sure if it is really better.
> 
> Regards,
> Helin

Since we only use 56 of the 64 bits as mask bits, I think using the union will make it easier to understand the
structure of the offload_mask.

Thanks,
Wang Xiao