Re: 2.5.69 Interrupt Latency

Andrew Morton (akpm@digeo.com)
Fri, 9 May 2003 14:28:28 -0700


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

ah, that helps.

This code was added to wakeup_hc(). It is called from uhci_irq():

+ /* Global resume for 20ms */
+ outw(USBCMD_FGR | USBCMD_EGSM, io_addr + USBCMD);
+ wait_ms(20);

The changelog just says "Minor patch for uhci-hcd.c"

Can you delete the wait_ms() and see if that is our culprit?
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