Re: 2.5.69 Interrupt Latency

[Andrew Morton]

Paul Fulghum <[e-mail]> 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?