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

[Olivier MATZ <olivier.matz-pdR9zngts4EAvxtiuMwx3w@public.gmane.org>]

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.


> --- 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?


>    */
>   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? 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.

Regards,
Olivier