Performance regression with rt2500pci (2.1.x vs 2.0.14)

Live forum:


16-03-2008 16:35:44

Hi there,

I'm now able to connect to my access point using version 2.1.4 of the rt2x00 driver, I consistently get much lower speeds. With 2.0.14 (specifically commit 1e0b4c51) I get speeds above 1000 kbps on the local network, with the current git HEAD (commit 5be66cd) the connection maxes out at 80 kbps.

This is even tough iwconfig claims that the BitRate is 54 Mb/s in both cases.

I'm attaching all the info I think may be pertinent, if you need anything else, I'm willing to do all kinds of tests D


16-03-2008 16:38:12

hit the attachment limit on the last post. Here come the slow versions (with driver version 2.1.4)


16-03-2008 20:49:10

Are the speeds you are quoting k bits/s or k Bytes/s, convention dictates using a small b for bits and capital B for Bytes? You will never achieve anything like the nominal 54 Mb/s rate, the theoretical maximum allowing for acknowledges etc is around 22 Mb/s. I used to be able to achieve that with rt73 with the device very close to the AP but at the moment I see closer to 15 Mb/s.

Tracking down performance problems can be a bit of effort as they often only affect one direction and the speed reported on the PC is only the Tx speed, you need to interrogate the AP if possible to find out what speed it is using. At the moment my AP seems to drop speed occasionally while transmitting but revert to 54M when there is no traffic.

If you want to try to diagnose the problem it would be helpful to look with wireshark and see what speeds packets are sent at in each direction and if there are lots of retries in one direction.


16-03-2008 21:02:03

The speeds reported are kBytes.

Speed packets, huh? Ok, I'll have a look at wireshark and see what I can diagnose.