[Click] About queues scheduling

[Roberto Riggio]

Hi,

I have some doubts about how push and pull are scheduled.

I'm running click on two wireless routers and I'm generating some
traffic between them using iPerf. Wireless interfaces are operating in
monitor mode and click is running in userspace.

The configuration essentially consist of:

KernelTun
  -> CheckIPHeader
  -> ... other push elements that set route etc. ...
  -> FullNoteQueue
  -> WifiEncap, SetTXRate, Radiotapencap
  -> ToDevice

The tx rate is statically set to 6 mbps. The strange this is that if
I generate traffic with Iperf at a very high rate (e.g. 10Mbps) I
do get an high packet loss as expected, but there is only one packet
in the queue.

I've added some debug message to the Queue' push and pull method
and this is what I get:

push
pull
pull
pull
pull
pull
pull
pull
pull
pull
pull
pull
push
pull
pull
pull
pull
pull
pull
pull
pull
pull
pull
pull
push

basically it seems that the driver is alway trying to pull from the 
queue, until the
_empty_note is put to sleep and only then a packet is pushed into the queue.

What I would expect is that incoming packet should be pushed in to the queue
and then eventually dropped if todevice cannot pull them all. Am I 
missing somthing?

R.

-- 
--------------------------------------------------------
Roberto Riggio, Ph.D.
CREATE-NET
Network&  Security Solutions for Pervasive Computing Systems (iNSPIRE)
Senior Researcher
Via alla Cascata 56/D - 38123 Povo Trento (Italy)
e-mail: roberto.riggio at create-net.org
Tel: (+39) 0461 408400 - interno/extension 708
Fax: (+39) 0461 421157
www.create-net.org/~rriggio
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