On Fri, 2003-05-09 at 16:28, Andrew Morton wrote:
> Paul Fulghum <paulkf@microgate.com> wrote:
> >
> > In the process of eliminating kernel options to isolate
> > the problem, eliminating USB completely appears to fix it.
> >
> > One machine (server) was using usb-uhci and
> > the other (laptop) was using usb-ohci.
> >
> > So it looks like something with USB in 2.5.68-bk11
The latency problem seen on the laptop turned out to
be a stupid mistake on my part: I enabled the ALI15XX
IDE controller option as a module instead of in kernel
and so it was not available for using DMA mode. Once
corrected the latency is running at a smooth 20us without
the >5ms spikes associated with PIO IDE.
Final Diagnosis:
server latency problem = USB wakeup_hc() delay added in 2.5.68-bk11
laptop latency problem = user with dain bramage
Thanks,
Paul
-- Paul Fulghum, paulkf@microgate.com Microgate Corporation, http://www.microgate.com- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
This archive was generated by hypermail 2b29 : Thu May 15 2003 - 22:00:53 EST