Posted by Dave Martindale on 01/21/08 16:09

Ilya Zakharevich <nospam-abuse@ilyaz.org> writes:

>> The USB bus isn't interrupt-driven -- it's polled (as I wrote),

>Do not see any significant difference. The poller would set up a
>wake-up call, which would generate an interrupt. [And, BTW, why my
>PCI hardware view shows that USB controllers use interrupts?]

More likely, the poller would set a wakeup call, which would add an
entry into a timer queue somewhere. The timer interrupts regularly,
and when the specified time has elapsed, the process that asked for the
wakeup is scheduled to run again. But it would need to wait for CPU
resources to do anything. It's unlikely to be called directly from the
timer interrupt handler.

Dave

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