On Thu, May 31, 2007 at 06:46:41PM +0200, Flemming Frandsen wrote: > Hi, I'm using Atheros 5212 minipci cards with the latest linux driver > (from SVN) and I find that I cannot get more than 24Mb/s out of the > wireless link, is that normal? > > I've tested it by routing traffic through the link and running iperf on > separate machines, so nothing runs on the net4801 machines other than > the kernel and top. > > I first tried setting one box to AP and the other to Sta and that got me > 13Mb/s with the CPU maxed out, when I switched to ahdemo mode (like > adhoc, but without any fancy stuff like mac addresses) that got me 22Mb/s. > > Then I upgraded to the very latest driver and that got me 24Mb/s, but > the CPU is still the bottleneck, which is really quite sad as I was > hoping to saturate the wireless link.
I have some questions: Do you expect much more than 24 Mb/s? According to my back-of-an-envelope computation, you cannot expect much more than 28 Mb/s with 1500-byte packets and a 54 Mb/s 802.11g link, which is about what I got under "ideal" conditions. How do you know that the CPU is the bottleneck? Sometimes CPU usage measurements are not reliable. What iperf parameters do you use? Are you measuring TCP or UDP performance? If TCP, are you sure that your window size is large enough? Do you have enough buffers Is the 4801 the "source" or "sink" for the data stream? If not, does the 4801 route or bridge from the wire to the wireless? Have you tried fixing the wireless transmission rate to the very highest? Can you isolate the devices under test from interference? Dave -- David Young OJC Technologies [EMAIL PROTECTED] Urbana, IL * (217) 278-3933 ext 24 _______________________________________________ Soekris-tech mailing list [email protected] http://lists.soekris.com/mailman/listinfo/soekris-tech
