Re: [lwip-users] Could TCP traffic slow down UDP?

[Kieran Mansley]

On 9 Jul 2012, at 19:52, Chen wrote:

> Hi there,
> 
> According to lwIP wiki: 
> 
> After lwip_init() is called, you must call tcp_tmr() every TCP_TMR_INTERVAL 
> milliseconds (default is 250 milliseconds). 
> 
> My quesiton: Is there any unpleasant side effect if I call it at a rate other 
> than 250ms? Further, how about randomized intervals, say 80ms, 83ms, 98ms.... 
> (I tried and haven't notice any yet but would like to hear from the gurus to 
> be sure)
> 
> I just like to tag this on an existing thread.

Slight variation would be fine.  Calling every 80ms instead of every 250 
probably isn't as lwIP uses this to control things like TCP retransmission.  If 
it is called too early, it may unnecessarily retransmit packets.  But it's easy 
to convert one to the other: just call a function that every third time 
(roughly 240ms) will call tcp_tmr()

Kieran