Re: USB performance bug since kernel 2.6.13 (CRITICAL???)

Lee Revell
2006-10-12T19:55:01Z

On Thu, 2006-10-12 at 12:33 -0700, Open Source wrote:
> I am using a device that submits URBs asynchronously using the libusb
> devio infrastructure. In version 2.6.12 I am able to submit and reap
> URBs for my particular application at a transaction rate of one per
> millisecond. A transaction consists of a single WRITE URB (< 512
> bytes) followed by a single READ URB (1024 bytes). Once I upgrade to
> version 2.6.13, the transactional rate drops to one per 4
> milliseconds!

The kernel's internal tick rate was lowered from 1000Hz to 250Hz
starting with 2.6.13. Rebuild with CONFIG_HZ=1000 and the performance
should return to normal.

Lee