Messages in this thread | | | Subject | Re: 2.5.69 Interrupt Latency | From | Paul Fulghum <> | Date | 14 May 2003 12:50:17 -0500 |
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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
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