On Mon, Jan 25, 2021 at 1:15 PM Ferruh Yigit [off-list ref] wrote:

From: Steve Yang <redacted>

"port config all max-pkt-len" command fails because it doesn't set the
'DEV_RX_OFFLOAD_JUMBO_FRAME' offload flag properly.

Commit in the fixes line moved the 'DEV_RX_OFFLOAD_JUMBO_FRAME' offload
flag update from 'cmd_config_max_pkt_len_parsed()' to 'init_config()'.
'init_config()' function is only called during testpmd startup, but the
flag status needs to be calculated whenever 'max_rx_pkt_len' changes.

The issue can be reproduce as [1], where the 'max-pkt-len' reduced and
'DEV_RX_OFFLOAD_JUMBO_FRAME' offload flag should be cleared but it
didn't.

Adding the 'update_jumbo_frame_offload()' helper function to update
'DEV_RX_OFFLOAD_JUMBO_FRAME' offload flag and 'max_rx_pkt_len'. This
function is called both by 'init_config()' and
'cmd_config_max_pkt_len_parsed()'.

Default 'max-pkt-len' value set to zero, 'update_jumbo_frame_offload()'
updates it to "RTE_ETHER_MTU + PMD specific Ethernet overhead" when it
is zero.
If '--max-pkt-len=N' argument provided, it will be used instead.
And with each "port config all max-pkt-len" command, the
'DEV_RX_OFFLOAD_JUMBO_FRAME' offload flag, 'max-pkt-len' and MTU is
updated.

[1]

<snip>

+/*
+ * Helper function to arrange max_rx_pktlen value and JUMBO_FRAME offload,
+ * MTU is also aligned if JUMBO_FRAME offload is not set.
+ *
+ * port->dev_info should be get before calling this function.

Should this be "port->dev_info should be set ..." instead?


<snip>

+       if (rx_offloads != port->dev_conf.rxmode.offloads) {
+               uint16_t qid;
+
+               port->dev_conf.rxmode.offloads = rx_offloads;
+
+               /* Apply JUMBO_FRAME offload configuration to Rx queue(s) */
+               for (qid = 0; qid < port->dev_info.nb_rx_queues; qid++) {
+                       if (on)
+                               port->rx_conf[qid].offloads |= DEV_RX_OFFLOAD_JUMBO_FRAME;
+                       else
+                               port->rx_conf[qid].offloads &= ~DEV_RX_OFFLOAD_JUMBO_FRAME;
+               }

Is it correct to set per-queue offloads that aren't advertised by the PMD
as supported in rx_queue_offload_capa?

+       }
+
+       /* If JUMBO_FRAME is set MTU conversion done by ethdev layer,
+        * if unset do it here
+        */
+       if ((rx_offloads & DEV_RX_OFFLOAD_JUMBO_FRAME) == 0) {
+               ret = rte_eth_dev_set_mtu(portid,
+                               port->dev_conf.rxmode.max_rx_pkt_len - eth_overhead);
+               if (ret)
+                       printf("Failed to set MTU to %u for port %u\n",
+                               port->dev_conf.rxmode.max_rx_pkt_len - eth_overhead,
+                               portid);
+       }
+
+       return 0;
+}
+

Applied and tested with a few iterations of configuring max packet size
back and forth between jumbo and non-jumbo sizes, also tried setting
max packet size using the command-line option, all seems good based
on rx offloads and packet forwarding.

Two minor questions above, otherwise LGTM.