Re: [dpdk-dev] [PATCH v3 3/3] app/testpmd:change tx_checksum command and csum forwarding engine

["Liu, Jijiang" <jijiang.liu@intel.com>]

> -----Original Message-----
> From: Olivier MATZ [mailto:olivier.matz@6wind.com]
> Sent: Thursday, December 11, 2014 6:53 PM
> To: Liu, Jijiang; dev@dpdk.org
> Subject: Re: [dpdk-dev] [PATCH v3 3/3] app/testpmd:change tx_checksum
> command and csum forwarding engine
> 
> Hi Jijiang,
> 
> Some more comments, in addition to the one I've made in the cover letter.
> Reference link for patchwork readers:
> http://dpdk.org/ml/archives/dev/2014-December/009886.html
> 
> On 12/10/2014 02:03 AM, Jijiang Liu wrote:
> > --- a/app/test-pmd/cmdline.c
> > +++ b/app/test-pmd/cmdline.c
> > @@ -316,16 +316,30 @@ static void cmd_help_long_parsed(void
> *parsed_result,
> >   			"    Disable hardware insertion of a VLAN header in"
> >   			" packets sent on a port.\n\n"
> >
> > -			"tx_cksum set (ip|udp|tcp|sctp|vxlan) (hw|sw)
> (port_id)\n"
> > +			"tx_cksum set (ip|udp|tcp|sctp) (hw|sw) (port_id)\n"
> >   			"    Select hardware or software calculation of the"
> >   			" checksum with when transmitting a packet using the"
> >   			" csum forward engine.\n"
> > -			"    ip|udp|tcp|sctp always concern the inner layer.\n"
> > -			"    vxlan concerns the outer IP and UDP layer (in"
> > -			" case the packet is recognized as a vxlan packet by"
> > -			" the forward engine)\n"
> > +			"    In the case of tunneling packet, ip|udp|tcp|sctp"
> > +			" always concern the inner layer.\n\n"
> > +
> > +			"tx_cksum set tunnel (hw|sw|none) (port_id)\n"
> > +			" Select hardware or software calculation of the"
> > +			" checksum with when transmitting a tunneling packet"
> > +			" using the csum forward engine.\n"
> > +			" The none option means treat tunneling packet as
> ordinary"
> > +			" packet when using the csum forward engine\n."
> > +			"    Tunneling packet concerns the outer IP, inner IP"
> > +			" and inner L4\n"
> >   			"    Please check the NIC datasheet for HW limits.\n\n"
> >
> > +			"tx_cksum set (outer-ip) (hw|sw) (port_id)\n"
> > +			"    Select hardware or software calculation of the"
> > +			" checksum with when transmitting a packet using the"
> > +			" csum forward engine.\n"
> > +			"    outer-ip always concern the outer layer of"
> > +			" tunneling packet.\n\n"
> > +
> >   			"tx_checksum show (port_id)\n"
> >   			"    Display tx checksum offload configuration\n\n"
> >
> 
> not sure we need 2 different commands for tx_cksum set (outer-ip) and tx_cksum
> set (ip|udp|tcp|sctp). As the syntax is exactly the same, it may result in less code
> to have only one command.

Why do we have a separate command for outer layer, I have explained this in other mail.
Do you agree on this?
 
> 
> > --- a/app/test-pmd/csumonly.c
> > +++ b/app/test-pmd/csumonly.c
> > @@ -256,17 +256,16 @@ process_outer_cksums(void *outer_l3_hdr, uint16_t
> outer_ethertype,
> >   	struct udp_hdr *udp_hdr;
> >   	uint64_t ol_flags = 0;
> >
> > -	if (testpmd_ol_flags & TESTPMD_TX_OFFLOAD_VXLAN_CKSUM)
> > -		ol_flags |= PKT_TX_UDP_TUNNEL_PKT;
> > -
> >   	if (outer_ethertype == _htons(ETHER_TYPE_IPv4)) {
> >   		ipv4_hdr->hdr_checksum = 0;
> >
> > -		if (testpmd_ol_flags & TESTPMD_TX_OFFLOAD_VXLAN_CKSUM)
> > +		if (testpmd_ol_flags &
> TESTPMD_TX_OFFLOAD_OUTER_IP_CKSUM)
> >   			ol_flags |= PKT_TX_OUTER_IP_CKSUM;
> > -		else
> > +		else {
> >   			ipv4_hdr->hdr_checksum = rte_ipv4_cksum(ipv4_hdr);
> > -	} else if (testpmd_ol_flags & TESTPMD_TX_OFFLOAD_VXLAN_CKSUM)
> > +			ol_flags |= PKT_TX_OUTER_IPV4;
> > +		}
> > +	} else if (testpmd_ol_flags & TESTPMD_TX_OFFLOAD_TUNNEL_CKSUM)
> >   		ol_flags |= PKT_TX_OUTER_IPV6;
> >
> >   	udp_hdr = (struct udp_hdr *)((char *)outer_l3_hdr + outer_l3_len);
> > @@ -300,11 +299,14 @@ process_outer_cksums(void *outer_l3_hdr, uint16_t
> outer_ethertype,
> >    *   Ether / (vlan) / outer IP|IP6 / outer UDP / VxLAN / Ether / IP|IP6 /
> >    *           UDP|TCP|SCTP
> >    *
> > - * The testpmd command line for this forward engine sets the flags
> > + * These testpmd command lines for this forward engine sets the flags
> >    * TESTPMD_TX_OFFLOAD_* in ports[tx_port].tx_ol_flags. They control
> > - * wether a checksum must be calculated in software or in hardware.
> > The
> > - * IP, UDP, TCP and SCTP flags always concern the inner layer.  The
> > - * VxLAN flag concerns the outer IP (if packet is recognized as a vxlan packet).
> > + * wether a checksum must be calculated in software or in hardware.
> > + * In the case of tunneling packet, the IP, UDP, TCP and SCTP flags
> > + * always concern the inner layer; the outer IP flag always concern
> > + * the outer layer; the tunnel flag is used to tell the NIC that it
> > + * is a tunneing packet, want hardware offload for outer layer,
> > + * or inner layer, or both.
> 
> tunneing -> tunneling
> 
> "the tunnel flag is used to tell the NIC that it is a tunneing packet, want hardware
> offload for outer layer, or inner layer, or both."
> 
> what does that mean?

Ok,
Will replace the above the description with the following:
The tunnel flag  is used to set/clear the flag of enabling TX tunneling packet checksum hardware offload in application.

> 
> 
> >    */
> >   static void
> >   pkt_burst_checksum_forward(struct fwd_stream *fs) @@ -376,7 +378,9
> > @@ pkt_burst_checksum_forward(struct fwd_stream *fs)
> >   		l3_hdr = (char *)eth_hdr + l2_len;
> >
> >   		/* check if it's a supported tunnel (only vxlan for now) */
> > -		if (l4_proto == IPPROTO_UDP) {
> > +		if (((testpmd_ol_flags &
> > +			TESTPMD_TX_OFFLOAD_NON_TUNNEL_CKSUM) == 0)
> > +			&& (l4_proto == IPPROTO_UDP)) {
> >   			udp_hdr = (struct udp_hdr *)((char *)l3_hdr + l3_len);
> >
> >   			/* check udp destination port, 4789 is the default @@ -
> 386,17
> > +390,23 @@ pkt_burst_checksum_forward(struct fwd_stream *fs)
> >   				tunnel = 1;
> >
> >   			/* currently, this flag is set by i40e only if the
> > -			 * packet is vxlan */
> > +			 * packet is a tunneling packet */
> >   			} else if (m->ol_flags & (PKT_RX_TUNNEL_IPV4_HDR |
> >   					PKT_RX_TUNNEL_IPV6_HDR))
> >   				tunnel = 1;
> >
> >   			if (tunnel == 1) {
> > +
> > +				if (testpmd_ol_flags
> > +					&
> TESTPMD_TX_OFFLOAD_TUNNEL_CKSUM)
> > +					ol_flags |= PKT_TX_UDP_TUNNEL_PKT;
> > +
> >   				outer_ethertype = ethertype;
> >   				outer_l2_len = l2_len;
> >   				outer_l3_len = l3_len;
> >   				outer_l3_hdr = l3_hdr;
> >
> > +				/* currently, only VXLAN packet is supported */
> >   				eth_hdr = (struct ether_hdr *)((char *)udp_hdr +
> >   					sizeof(struct udp_hdr) +
> >   					sizeof(struct vxlan_hdr));
> > @@ -434,7 +444,7 @@ pkt_burst_checksum_forward(struct fwd_stream *fs)
> >   		/* step 4: fill the mbuf meta data (flags and header lengths) */
> >
> >   		if (tunnel == 1) {
> > -			if (testpmd_ol_flags &
> TESTPMD_TX_OFFLOAD_VXLAN_CKSUM) {
> > +			if (testpmd_ol_flags &
> TESTPMD_TX_OFFLOAD_TUNNEL_CKSUM) {
> >   				m->outer_l2_len = outer_l2_len;
> >   				m->outer_l3_len = outer_l3_len;
> >   				m->l2_len = l4_tun_len + l2_len; @@ -505,7
> +515,7 @@
> > pkt_burst_checksum_forward(struct fwd_stream *fs)
> >   					"m->l4_len=%d\n",
> >   					m->l2_len, m->l3_len, m->l4_len);
> >   			if ((tunnel == 1) &&
> > -				(testpmd_ol_flags &
> TESTPMD_TX_OFFLOAD_VXLAN_CKSUM))
> > +				(testpmd_ol_flags &
> TESTPMD_TX_OFFLOAD_TUNNEL_CKSUM))
> >   				printf("tx: m->outer_l2_len=%d m-
> >outer_l3_len=%d\n",
> >   					m->outer_l2_len, m->outer_l3_len);
> >   			if (tso_segsz != 0)
> > diff --git a/app/test-pmd/testpmd.h b/app/test-pmd/testpmd.h index
> > f8b0740..09caa6a 100644
> > --- a/app/test-pmd/testpmd.h
> > +++ b/app/test-pmd/testpmd.h
> > @@ -125,10 +125,20 @@ struct fwd_stream {
> >   #define TESTPMD_TX_OFFLOAD_TCP_CKSUM         0x0004
> >   /** Offload SCTP checksum in csum forward engine */
> >   #define TESTPMD_TX_OFFLOAD_SCTP_CKSUM        0x0008
> > -/** Offload VxLAN checksum in csum forward engine */
> > -#define TESTPMD_TX_OFFLOAD_VXLAN_CKSUM       0x0010
> > +/** Offload tunneling packet checksum in csum forward engine */
> > +#define TESTPMD_TX_OFFLOAD_TUNNEL_CKSUM      0x0010
> >   /** Insert VLAN header in forward engine */
> >   #define TESTPMD_TX_OFFLOAD_INSERT_VLAN       0x0020
> > +/**
> > + * Offload outer-IP checksum in csum forward engine
> > + * for tunneling packet
> > + */
> > +#define TESTPMD_TX_OFFLOAD_OUTER_IP_CKSUM    0x0040
> > +/**
> > + * For a tunneling packet, user requests HW offload for its outer
> > + * layer checksum, and don't care is it a tunneled packet or not.
> > + */
> > +#define TESTPMD_TX_OFFLOAD_NON_TUNNEL_CKSUM  0x0080
> >
> >   /**
> >    * The data structure associated with each port.
> >
> 
> For now, I did not check the implementation of the patch. I'm not sure I
> understand the specifications, so I cannot check if the code conforms to it.
> 
> How this patch is tested? 
Yes, it is tested for i40e and ixgbe.

> I think a report similar to
> http://dpdk.org/ml/archives/dev/2014-November/007991.html would help to
> verify that it works (at least on one driver), and to understand the test-pmd API
> and the different use cases.
Ok, will send test report.

> Regards,
> Olivier