Comment 13 for bug 1032342

On Fri, 3 Aug 2012, mat brown wrote:

> Already done as requested by the Ubuntu devs. File is here:
> https://launchpadlibrarian.net/111697628/usbmon.out
>
> The transfer which created that file was generated using dd
> if=/dev/zero of=/media/littlun/tmp oflag=direct bs=120K count=2K

It's odd. The usbmon log shows things working pretty well most of the
time, with transfer speeds around 200 Mb/s, but every now and then a
single 120-KB transfer takes more than half a second!

I have no idea why. We can rule out hardware problems because it
doesn't happen under Fedora. Maybe interrupt delivery gets delayed
somehow under Ubuntu, or maybe something is different in the xhci-hcd
driver. Can you compare the driver source files?

To do more serious testing will require you to build your own kernel,
or at least, your own version of the driver.

Alan Stern