Re: [dpdk-dev] [PATCH v4] examples/l2fwd: add cmdline option for forwarding port info

[Pavan Nikhilesh Bhagavatula <pbhagavatula@marvell.com>]

Hi Vipin,

>Hi Pavan,
>
>snipped
>> >
>> >Should we check & warn the user if
>> >1. port speed mismatch
>> >2. on different NUMA
>> >3. port pairs are physical and vdev like tap, and KNI (performance).
>> >
>>
>> Sure, it can be a separate patch as it will be applicable for multiple
>examples.
>I believe this patch is for example `l2fwd`. But you would like to have to
>updated for all `example`. I am ok for this.
>
>snipped
>> >
>> >Should not the check_port_pair be after this? If the port is not
>> >enabled in port_mask will you skip that pair? or skip RX-TX from that
>port?
>>
>> We check every port pair against l2fwd_enabled_port_mask in
>> check_port_pair_config()
>
>
>>
>snipped
>> >
>> >As mentioned above there can ports in mask which might be
>disabled for
>> >port pair. Should not that be skipped rather than setting last port rx-
>> >tx loopback?
>>
>> There could be scenarios where user might want to test 2x10G and
>1x40G Why
>> force the user to explicitly mention 1x40G as port pair of itself in the
>portpair
>> config?
>I am not sure if I follow your thought, as your current port map only
>allows `1:1` mapping by `struct port_pair_params`. This can be to self
>like `(port0:port0),(port1:port1)` or `(port-0:port-1)`.
>
>1. But current `l2fwd_parse_port_pair_config` does not consider the
>same port mapping as we have hard check for `if (nb_port_pair_params
>>= RTE_MAX_ETHPORTS/2)`.
>
>2. `l2fwd_enabled_port_mask` is global variable of user port mask. This
>can contain both valid and invalid mask. Hence we check
>`l2fwd_enabled_port_mask & ~((1 << nb_ports) - 1)`.
>
>3. can these scenarios are true if we invoke `check_port_pair_config`
>before actual port_mask check.
> a. there are only 4 ports, hence possible mask is `0xf`.
> b. user passes port argument as `0xe`
> c. `check_port_pair_config` gets masks for `(1,3)` as input and
>populates `port_pair_config_mask`.
> d.  As per the code, port 2 which is valid port and part of user port mask
>will have lastport (which is port 3)? May be I did understand the logic
>correct. Can you help me?

Here user needs to explicitly mention (2,2) for port 2 to be setup else it 
will be skipped. 
If you see `check_port_pair_config` below we disable the ports that are not 
Mentioned in portmap.

"
check_port_pair_config(void)
{

<snip>
		port_pair_config_mask |= port_pair_mask;
	}

	l2fwd_enabled_port_mask &= port_pair_config_mask;

	return 0;
}
"


>
>So my concerns are 1) there is no same port mapping, 2) my
>understanding on lastport logic is not clear and 3) as per the code there
>is 1:N but 1:1.
>
>Hence there should be sufficient warning to user if port are of wrong
>speed and NUMA.

Unless the user disables stats using -T 0 option all the prints will be skipped.

>
>Note: current speed can be fetched only if the port are started too (in
>Fortville).
>
>snipped