[rt2x00-users] So many USB interrupts

[Michael Fox]

Hi all. 

I'm using rt2800usb on a 32-bit machine with a USB 1.1 (full-speed, 12Mbps, uhci) port. linux-2.6.33 with a very recent compat-wireless.

I have also tested this device for comparison on a 64-bit machine with a USB 2.0 (480Mbps, ehci) port. linux-3.3.

It works well. The only problem is that on the 32-bit-USB-1.1 machine there's a lot of interrupts, about 1000/s when the interface comes up, and up to 3000/s depending on traffic. This bogs down the machine a bit. By comparison, on the 64-bit-USB-2.0 machine, there seems to be about 200 interrupts/s. A further comparison is a built in, iwlagn device which runs at about 20 interrupts/s.

My question for the group is: Is this a bug, or is this behavior expected based on the limitations of USB 1.1 or the limitations of a slower 32-bit machine? If it is a bug, what further steps would you recommend for understanding and fixing it? 

-- 
Michael Fox
Sent with Sparrow (http://www.sparrowmailapp.com/?sig)

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://rt2x00.serialmonkey.com/pipermail/users_rt2x00.serialmonkey.com/attachments/20120316/86d67f3b/attachment.html>