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

Bruce Richardson bruce.richardson at intel.com
Mon May 25 11:29:37 CEST 2020


On Sun, May 24, 2020 at 06:13:22PM +0200, Thomas Monjalon wrote:
> Bruce, as maintainer of l2fwd example, any opinion about this change?
> 
Assuming all previous discussion on it is resolved, I'm fine with this
patch, though I suspect it will only make 20.08 now.

Acked-by: Bruce Richardson <bruce.richardson at intel.com>

> 
> 11/05/2020 02:23, Pavan Nikhilesh Bhagavatula:
> > 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
> 
> 
> 
> 


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