Pipe queues

rihad rihad at mail.ru
Mon Dec 10 11:04:04 PST 2007


I'm having a hard time to understand what pipe queues are with respect 
to bandwidth limitation. ipfw(8) and dummynet(4) manuals didn't help me 

How does dummynet's traffic shaping function? Why does it need a queue 
at all? As each connection's queue takes some memory, can I just disable 
the queueing, or set its size to 1 slot (1500 bytes)? What if I set it 
to 10000 slots, why should it wait to fill the queue before starting to 
send stuff out the network interface? As packets arrive, AFAIK they are 
stored in mbufs in system memroy. Do pipe queues also use mbufs? I might 
be servicing hundreds of pipes simultaneously, this is why I'm concerned 
about memory use.

Thank you for any insights.

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