[dpdk-dev] [PATCH] examples/ip_fragmentation: support bigger packets

[Ananyev, Konstantin]

Hi, 

> 
> Adding MTU and mbuf size configuration to the application's command
> line, in order to be able to receive all packet sizes by the NIC and
> DPDK application.
> The maximum transmission unit (MTU) is the largest size packet in
> bytes that can be sent on the network, therefore before adding MTU
> parameter, the NIC could not receive packets larger than 1500 bytes,
> which is the default MTU size.

I wonder why is that?
Currently ip_fragmentation sets max_rx_pkt_len to up to 9.5KB:

static struct rte_eth_conf port_conf = {
        .rxmode = {
                .max_rx_pkt_len = JUMBO_FRAME_MAX_SIZE,
...

local_port_conf.rxmode.max_rx_pkt_len = RTE_MIN(
                    dev_info.max_rx_pktlen,
                    local_port_conf.rxmode.max_rx_pkt_len);

That in theory should be enough to enable jumbo frame RX.
Did you find it is not working as expected, if yes on which NIC?

> The mbuf is the memory buffer that contains the packet. Before adding
> mbuf parameter, the DPDK application could not receive packets larger
> than 2KB, which is the default mbuf size.

Again why is that?
All packets that do support scatter-gather RX should be able to RX
frames bigger then mbuf size (if properly configured of course).
Are you trying to make it work on NICs with no multi-segment support for RX/TX?
But then how you plan to do TX (usually it is symmetric for RX/TX)?

> 
> Signed-off-by: Noa Ezra <noae at mellanox.com>
> ---
>  doc/guides/sample_app_ug/ip_frag.rst | 18 ++++++++-
>  examples/ip_fragmentation/main.c     | 77 +++++++++++++++++++++++++++++++++---
>  2 files changed, 88 insertions(+), 7 deletions(-)
> 
> diff --git a/doc/guides/sample_app_ug/ip_frag.rst b/doc/guides/sample_app_ug/ip_frag.rst
> index 7914a97..13933c7 100644
> --- a/doc/guides/sample_app_ug/ip_frag.rst
> +++ b/doc/guides/sample_app_ug/ip_frag.rst
> @@ -53,7 +53,7 @@ Application usage:
> 
>  .. code-block:: console
> 
> -    ./build/ip_fragmentation [EAL options] -- -p PORTMASK [-q NQ]
> +    ./build/ip_fragmentation [EAL options] -- -p PORTMASK [-q NQ] [-b MBUFSIZE] [-m MTUSIZE]
> 
>  where:
> 
> @@ -61,6 +61,15 @@ where:
> 
>  *   -q NQ is the number of queue (=ports) per lcore (the default is 1)
> 
> +*   -b MBUFSIZE is the mbuf size in bytes (the default is 2048)
> +
> +*   -m MTUSIZE is the mtu size in bytes (the default is 1500)
> +
> +The MTU is the maximum size of a single data unit that can be transmitted over the network, therefore it must be
> +greater than the requested max packet size, otherwise the NIC won't be able to get the packet.
> +The mbuf is a buffer that is used by the DPDK application to store message buffers.If not using scatter then the
> +mbuf size must be greater than the requested max packet size, otherwise the DPDK will not be able to receive the
> +packet.
>  To run the example in linuxapp environment with 2 lcores (2,4) over 2 ports(0,2) with 1 RX queue per lcore:
> 
>  .. code-block:: console
> @@ -96,6 +105,13 @@ To run the example in linuxapp environment with 1 lcore (4) over 2 ports(0,2) wi
> 
>      ./build/ip_fragmentation -l 4 -n 3 -- -p 5 -q 2
> 
> +To run the example with defined MTU size 4000 bytes and mbuf size 9000 byes:
> +
> +.. code-block:: console
> +
> +    ./build/ip_fragmentation -l 4 -n 3 -- -p 5 -m 4000 -b 9000
> +
> +
>  To test the application, flows should be set up in the flow generator that match the values in the
>  l3fwd_ipv4_route_array and/or l3fwd_ipv6_route_array table.
> 
> diff --git a/examples/ip_fragmentation/main.c b/examples/ip_fragmentation/main.c
> index 17a877d..0cf23b4 100644
> --- a/examples/ip_fragmentation/main.c
> +++ b/examples/ip_fragmentation/main.c
> @@ -111,6 +111,10 @@
> 
>  static int rx_queue_per_lcore = 1;
> 
> +static int mbuf_size = RTE_MBUF_DEFAULT_BUF_SIZE;
> +
> +static int mtu_size = ETHER_MTU;
> +
>  #define MBUF_TABLE_SIZE  (2 * MAX(MAX_PKT_BURST, MAX_PACKET_FRAG))
> 
>  struct mbuf_table {
> @@ -425,7 +429,6 @@ struct rte_lpm6_config lpm6_config = {
>  		 * Read packet from RX queues
>  		 */
>  		for (i = 0; i < qconf->n_rx_queue; i++) {
> -
>  			portid = qconf->rx_queue_list[i].portid;
>  			nb_rx = rte_eth_rx_burst(portid, 0, pkts_burst,
>  						 MAX_PKT_BURST);
> @@ -455,9 +458,11 @@ struct rte_lpm6_config lpm6_config = {
>  static void
>  print_usage(const char *prgname)
>  {
> -	printf("%s [EAL options] -- -p PORTMASK [-q NQ]\n"
> +	printf("%s [EAL options] -- -p PORTMASK [-q NQ] [-b MBUFSIZE] [-m MTUSIZE]\n"
>  	       "  -p PORTMASK: hexadecimal bitmask of ports to configure\n"
> -	       "  -q NQ: number of queue (=ports) per lcore (default is 1)\n",
> +	       "  -q NQ: number of queue (=ports) per lcore (default is 1)\n"
> +	       "  -b MBUFSIZE: set the data size of mbuf\n"
> +	       "  -m MTUSIZE: set the MTU size\n",
>  	       prgname);
>  }
> 
> @@ -496,6 +501,38 @@ struct rte_lpm6_config lpm6_config = {
>  	return n;
>  }
> 
> +static int
> +parse_mbufsize(const char *q_arg)
> +{
> +	char *end = NULL;
> +	unsigned long mbuf;
> +
> +	/* parse hexadecimal string */

You expect decimal string below.

> +	mbuf = strtoul(q_arg, &end, 10);
> +	if ((q_arg[0] == '\0') || (end == NULL) || (*end != '\0'))
> +		return -1;

You probably need to set and test errno too.

> +	if (mbuf == 0)
> +		return -1;
> +
> +	return mbuf;
> +}


These 2 parse functions looks identical.
Why you need two of them?

> +
> +static int
> +parse_mtusize(const char *q_arg)
> +{
> +	char *end = NULL;
> +	unsigned long mtu;
> +
> +	/* parse hexadecimal string */
> +	mtu = strtoul(q_arg, &end, 10);
> +	if ((q_arg[0] == '\0') || (end == NULL) || (*end != '\0'))
> +		return -1;
> +	if (mtu == 0)
> +		return -1;
> +
> +	return mtu;
> +}
> +
>  /* Parse the argument given in the command line of the application */
>  static int
>  parse_args(int argc, char **argv)
> @@ -510,7 +547,7 @@ struct rte_lpm6_config lpm6_config = {
> 
>  	argvopt = argv;
> 
> -	while ((opt = getopt_long(argc, argvopt, "p:q:",
> +	while ((opt = getopt_long(argc, argvopt, "p:q:b:m:",
>  				  lgopts, &option_index)) != EOF) {
> 
>  		switch (opt) {
> @@ -534,6 +571,26 @@ struct rte_lpm6_config lpm6_config = {
>  			}
>  			break;
> 
> +		/* mbufsize */
> +		case 'b':
> +			mbuf_size = parse_mbufsize(optarg);
> +			if (mbuf_size < 0) {
> +				printf("invalid mbuf size\n");
> +				print_usage(prgname);
> +				return -1;
> +			}
> +			break;
> +
> +		/* mtusize */
> +		case 'm':
> +			mtu_size = parse_mtusize(optarg);
> +			if (mtu_size < 0) {
> +				printf("invalid mtu size\n");
> +				print_usage(prgname);
> +				return -1;
> +			}
> +			break;
> +
>  		/* long options */
>  		case 0:
>  			print_usage(prgname);
> @@ -777,9 +834,8 @@ struct rte_lpm6_config lpm6_config = {
>  			RTE_LOG(INFO, IP_FRAG, "Creating direct mempool on socket %i\n",
>  					socket);
>  			snprintf(buf, sizeof(buf), "pool_direct_%i", socket);
> -
>  			mp = rte_pktmbuf_pool_create(buf, NB_MBUF, 32,
> -				0, RTE_MBUF_DEFAULT_BUF_SIZE, socket);
> +				0, mbuf_size, socket);
>  			if (mp == NULL) {
>  				RTE_LOG(ERR, IP_FRAG, "Cannot create direct mempool\n");
>  				return -1;
> @@ -892,6 +948,15 @@ struct rte_lpm6_config lpm6_config = {
>  		    dev_info.max_rx_pktlen,
>  		    local_port_conf.rxmode.max_rx_pkt_len);
> 
> +		/* set the mtu to the maximum received packet size */
> +		ret = rte_eth_dev_set_mtu(portid, mtu_size);
> +		if (ret < 0) {
> +			printf("\n");
> +			rte_exit(EXIT_FAILURE, "Set MTU failed: "
> +				"err=%d, port=%d\n",
> +			ret, portid);
> +		}
> +
>  		/* get the lcore_id for this port */
>  		while (rte_lcore_is_enabled(rx_lcore_id) == 0 ||
>  		       qconf->n_rx_queue == (unsigned)rx_queue_per_lcore) {
> --
> 1.8.3.1