[LTP] [PATCH v2 1/3] network/stress/multicast/packet-flood: Update to new API

[Alexey Kodanev]

On 19.11.2020 10:49, Joerg Vehlow wrote:
> Hi Alexey,
>> The following command should support both udp/udp6:
>>

Hi Joerg,

>> local mcast_port=$(tst_get_unused_port ipv${TST_IPVER} dgram)
> Actually find_portbundle doesn't distinguish between ipv6 and ipv4 when 
> looking for a window of free ports, so it works for both variants. The 

I see, find_portbundle is just a wrapper for netstat and it's not setting
any address family, so netstat list all.

> only thing that can happen, is that it finds no free ports at all, even 
> if there are some free ports, but that is probably highly unlikely.
> Still I would say: Let's get rid of this function and remove usage as we 
> go: I will change it anyway, because I don't like this.
>> This check can be replaced with
>>
>> ROD ns-mcast_receiver -f $TST_IPVER -I $(tst_iface lhost) -m $mcast_addr -p $mcast_port -b
> ACK
>> What if we swap sender and receiver, i.e.
>>
>> local ns_opts="-f $TST_IPVER -p $mcast_port"
>>
>> tst_rhost_run -s -c "ns-mcast_receiver $ns_opts -I $(tst_iface rhost) -m $mcast_addr -b"
>> EXPECT_PASS ns-udpsender -D $mcast_addr $ns_opts -s 32767 -m -I $(tst_iface) -t $NS_DURATION
>>
>> By default, ltp is using network namespace, so it's probably better
>> to run the background service there.
> I think the "thing-under-test" here is the receiver, not the sender. I 
> don't see any benefit swapping this, it will only move the test to the 
> wrong machine, if network namespaces are not in us
>>

Both machines are under test.

>>> +	done
>>> +
>>> +	sleep $NS_DURATION
>>
>> It would be nice to have a small loop instead of a single 'sleep' and
>> periodically check that the background senders are really running...
> I also don't normally like sleeps, but  actually the way the test is 
> implemented at the moment it would make little sense to add all the 
> complexity required, to collect pids, to check the senders and implement 
> a timeout Right after the last ns-udpsender is started, that runs for 
> NS_DURATION, the sleep is executed for NS_DURATION. Even if the sleep 
> exits before ns-udpsender, it doesn't matter, because it is just a bit 
> earlier and the test time is actually variable. I wouldn't change this 
> to be more complex, although I would design it differently, if I would 
> implement the this as a new test.
> An alternative would be to not background the last ns-udpsender 
> execution, but that could be a bit obscure

OK