Subject: Re: multiple wireless cards
Newsgroups: gmane.linux.drivers.madwifi.devel
Date: 2008-07-26 11:36:16 GMT (23 weeks, 6 days, 15 hours and 53 minutes ago)
This is my network topology: A<--B-->C To exclude Interference between antennas I replicated the same experiments with two soekris instead of one. Specifically, I use the same antenna placement but I sobstituted the second wireless card of B with another dedicated soekris A<--B D-->C In this scenario I achieved a per flow throughput of about 24-25 Mbps. So there isn't interference between antennas. To excluded interference between wireless cards I repeated the same experiment of the first scenario using a PC equipped with an Athlon 64 processor (2043.086 MHz processor with 1GB of memory). I put both the wireless cards into two contiguous PCI slots using two miniPCI to PCI single Slot Adapter so that the wireless cards are about 1-2 cm from each other. Also in this case both the wireless cards are able to work simultaneously and I obtained a per flow throughput of about 24-25Mbps. I also opened the case of the soekris B and D of the second scenario and I bring the wireless card of soekris B near to the wireless card of soekris D (varying their relative position ). Also in this case I obtained a per flow throughput of about 24-25Mbps. This is a snapshot of the CPU utilization obtained with the top command when both wireless cards work simultaneously: Cpu(s): 4.2%us, 27.8%sy, 0.0%ni, 0.0%id, 0.0%wa, 15.2%hi, 52.8%si, 0.0%st As you can observe, the amount of time the CPU has been servicing software interrupts is about 52.8%, and the total CPU utilization is about 100%. When I only use one wireless cards, the output of the top command is very similar to that obtained with two wireless card Specifically, the %si field is about 50%, and the total CPU usage is about 100%. It's very strange that also with one wireless card and one asimptotic UDP flow the %si filed is about 50%. Consequently, I think that the problem is related to the madwifi driver or to the soekris board. Any suggestion? Emilio ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/