[Click] Problem in click and madwifi interaction

[Ramana]

Hi,

I am working with click and madwifi driver for a simple task of
classifying the packets and sending them to either ath0 or host.
(script is given below). I am running this script on soekris single
board computers (operating at 233 MHz, 128 MB RAM etc.,).

There will be 3 flows going from a Station to an AP. In normal mode
(i.e., without click enabled), there are no packet drops.

However, for the same configuration, there are many packets (about
2000-4000 packets) getting dropped at the sending station when I
enabled click.

I could overcome this problem by increasing buffer limits in the
driver  (i.e, changing the value of TAIL_DROP_COUNT from 50 to 400 in
madwifi driver). However, we wanted it without increasing buffer
limits as it is leading to another problem of increasing delays etc.

So, my question is why the packets are getting dropped with click?. Is
there any solution?.

Also kindly share the details of how click (todevice) interacts with
madwifi device driver.

Regards
Ramana
-------------------------------------------------------------------------------

tod0:: Queue(100) ->ToDevice(ath0);
tohs::ToHost()

host :: FromHost(fake0, 172.16.4.90/16, ETHER 00:0B:6B:57:BD:51)
fod0 :: FromDevice(ath0)

aq0 :: ARPQuerier(172.16.4.90, 00:0B:6B:57:BD:51);


hs_cl :: Classifier(12/0806 20/0001, 12/0806 20/0002, 12/0800,-);
f0_cl :: Classifier(12/0806 20/0001, 12/0806 20/0002, -);

host  ->  hs_cl;
fod0  -> f0_cl;

hs_cl[0] -> ARPResponder(0.0.0.0/0 ff:ff:ff:ff:ff:ff) -> tohs;
hs_cl[1] -> Discard;
hs_cl[3] -> tod0;
f0_cl[0] -> ARPResponder(172.16.4.90 00:0B:6B:57:BD:51) -> tod0;
f0_cl[1] -> [1]aq0;
f0_cl[2] -> tohs

rt :: RadixIPLookup(172.16.0.0/16 172.16.4.81 0, 0.0.0.0 1)
ip::Strip(14) ->  CheckIPHeader(CHECKSUM false) -> [0]rt;
hs_cl[2] -> ip
rt[0] ->  [0]aq0;
rt[1] ->  Discard;
aq0[0] -> tod0;
aq0[1] -> tod0;


-- 
Regards
Ramana