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

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

[Noa Ezra]

In some vendors the RX and TX configuration must be the same, therefore
the MTU size need to be equal to max_rx_pkt_len.
The MTU is the largest size packet in bytes that can be sent on the
network, therefore before changing this parameter, the NIC could not
receive packets larger than 1500 bytes, which is the default MTU size.
In addition, scatter-gather need to be enabled in order to receive
frames bigger than mbuf size.

Cc: stable@dpdk.org

Signed-off-by: Noa Ezra <noae@mellanox.com>
---
 examples/ip_fragmentation/main.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/examples/ip_fragmentation/main.c b/examples/ip_fragmentation/main.c
index 17a877d..d294f5f 100644
--- a/examples/ip_fragmentation/main.c
+++ b/examples/ip_fragmentation/main.c
@@ -141,6 +141,7 @@ struct lcore_queue_conf {
 		.max_rx_pkt_len = JUMBO_FRAME_MAX_SIZE,
 		.split_hdr_size = 0,
 		.offloads = (DEV_RX_OFFLOAD_CHECKSUM |
+			     DEV_RX_OFFLOAD_SCATTER |
 			     DEV_RX_OFFLOAD_JUMBO_FRAME),
 	},
 	.txmode = {
@@ -892,6 +893,16 @@ 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,
+			local_port_conf.rxmode.max_rx_pkt_len);
+		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

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

[Ananyev, Konstantin]

Hi ,

> 
> In some vendors the RX and TX configuration must be the same, therefore
> the MTU size need to be equal to max_rx_pkt_len.
> The MTU is the largest size packet in bytes that can be sent on the
> network, therefore before changing this parameter, the NIC could not
> receive packets larger than 1500 bytes, which is the default MTU size.
> In addition, scatter-gather need to be enabled in order to receive
> frames bigger than mbuf size.
> 
> Cc: stable@dpdk.org
> 
> Signed-off-by: Noa Ezra <noae@mellanox.com>
> ---
>  examples/ip_fragmentation/main.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/examples/ip_fragmentation/main.c b/examples/ip_fragmentation/main.c
> index 17a877d..d294f5f 100644
> --- a/examples/ip_fragmentation/main.c
> +++ b/examples/ip_fragmentation/main.c
> @@ -141,6 +141,7 @@ struct lcore_queue_conf {
>  		.max_rx_pkt_len = JUMBO_FRAME_MAX_SIZE,
>  		.split_hdr_size = 0,
>  		.offloads = (DEV_RX_OFFLOAD_CHECKSUM |
> +			     DEV_RX_OFFLOAD_SCATTER |
>  			     DEV_RX_OFFLOAD_JUMBO_FRAME),
>  	},
>  	.txmode = {
> @@ -892,6 +893,16 @@ 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,
> +			local_port_conf.rxmode.max_rx_pkt_len);
> +		if (ret < 0) {
> +			printf("\n");
> +			rte_exit(EXIT_FAILURE, "Set MTU failed: "
> +				"err=%d, port=%d\n",
> +			ret, portid);
> +		}
> +

It probably doesn't matter for that particular case, but
shouldn't set_mtu() be done after dev_configure()?
To avoid situation when max_rx_pkt_len will be set by set_mtu()
and then overwritten by dev_configure().
Konstantin 


>  		/* 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