Re: PS/2 mouse latency was Re: [linux-audio-dev] Re: [DATAPOINT] kernels and latencies

From: Andrew Morton (andrewm@uow.edu.au)
Date: Tue Jul 04 2000 - 21:53:08 EST


Andi Kleen wrote:
>
> The PS/2 mouse interface has an incestuous relation to the keyboard
> controller; they use the same registers. Keyboard controller is writen
> to regularly in the keyboard interrupt when you press a key. Both
> have to be serialized.

Hi, Andi.

Writing to the k/b is a simple outb() and yes, the statefulness of the
host<->mouse-or-kb protocol presumably requires the higher level
serialisation.

But my question was: how often are aux_write_dev() and aux_write_ack()
actually called?

>From my reading, it's only when:

- The system is booted
- /dev/psaux is opened
- /dev/psaux is written to

If these are sufficiently rare events, we can shrug and move on, no?

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