Re: RE: [lwip-devel] Small request regarding autoip.h

[Simon Goldschmidt]

Bill Auerbach wrote:
> >I guess for AutoIP, 250ms are OK: the minimum delay used is 1 second. We
> >only have to keep an eye on the jitter: Currently, when we want to delay
> >1 second, we might end up with 900ms (which is OK, I guess). However,
> >when increasing the timer to 250ms, we could end up with a 750ms delay
> >only, so we might have to increase ttw by one.
> 
> I don't see this much jitter - or it's not apparent :)

OK, since the only case where ttw is set from outside the timer is the random 
interval, it's OK. Only if ttw was set outside the timer function, there could 
be a jitter because the first period might be shorter than expected (depending 
on when ttw is set vs. when the timer expires). However, since that's not the 
case, increasing the timer to 250 ms should be OK.

> >For IGMP, I'm not totally sure: The protocol includes a "Max Response
> >Time" given in 1/10 seconds (which is why the igmp_timer is set to
> >100ms, I guess). However, I don't suspect it to be smaller than 250ms,
> >so increasing the timer should be OK when the code is adjusted
> >accordingly.
> 
> I would test this if I used it or if I knew what effect to look for by
> changing the timer.  It sounds like with 1/10th of seconds timing that
> it's
> not a good candidate to change.

I guess so. Also, I don't mind that timer being 100ms since I don't use igmp, 
hehe. :-)

> Did your timer additions do anything to handle the lwIP timer calls? 
> Would
> it be a nice feature to have a single function that monitors elapsed time
> (in whatever resolution the user will call this function) and have this
> feature make the appropriate calls at the right intervals to lwIP
> functions?

That's what sys_check_timeouts() does for the NO_SYS==1 case. However, for the 
NO_SYS==0 case, it's not done yet but should be before 1.4.0.

Simon
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