Error: Timed-out thinking up post title.
I’m sure that no-one has noticed that I’ve been fairly silent on the blogging front for a while. I took a three month break from the Ph.D to do some work for Cambridge Silicon Radio. The experience working on a real-world project was great and the project itself was both interesting and challenging.
I am however looking forward to getting back into the Ph.D work. I’ve still got a week or so before the Ph.D kicks back in so at the moment I’m doing some driver work for RuralLink – specifically getting MadWiFi working better on the CPE/AP devices.
I spent a week or so before the CSR work started looking into performance improvements for MadWiFi. After spending quite a bit of time with oprofile I found a couple of areas in the driver which were causing a large number of PCI transactions to take place unnecessarily. Now, on a laptop or desktop platform this didn’t really make much difference. On an already resource-starved platform such as the Soekris 4526 however, this was resulting in some pretty significant overhead. A couple of patches to MadWiFi later (a couple merged upstream already, one that’s a bit more of a hack specific to our needs) and we’re seeing some much nicer throughput numbers. Off the top of my head, we went from being able to bridge about 9-10 Mbit/s of traffic over wireless through the wired ethernet to about ~15 Mbit/s.
The other neat hack we did was to create a transparent wireless bridge by hacking the ad-hoc demo mode to use 4-address 802.11 frames. This could already be done in other modes, but we really like ad-hoc demo due to its utter simplicity – no associations, no beacons, nothing – just passing frames.
Right now we’re working on implementing our own rate control algorithm. We seem to run into far too many problems on our networks with rate control and Perry came up with a neat idea – as is his wont – so we’re running with it. At the same time we’re looking at using it as a chance to collect large amounts of performance data to give us some deeper knowledge as to what’s going on on our networks. Hopefully lots more info on that soon.
At some point in the (very) near future I need to start thinking about the Ph.D again – I’m starting to think that I should be putting more of a measurement focus into it, but I need to nail down a few ideas first. And maybe play a bit of Guitar Hero as well 
1 comment August 9th, 2007