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SubjectRe: PS/2 mouse latency was Re: [linux-audio-dev] Re: [DATAPOINT] kernels and latencies
[Cc list trimmed]
Andi Kleen writes:
> On Tue, Jul 04, 2000 at 12:04:59PM -0600, Richard Gooch wrote:
> > So with all that locking, the ISR may have to wait a long time for the
> > lock to yield. Even if other interrupts are not blocked, this will
> > still delay BH/tasklet processing, not to mention scheduling
> > latencies.
>
> It would be possible to use a work queue similar to the socket lock:
> You lock against interrupts with a counter and when it is >0 they
> queue items (in this case function pointer + data) into a special
> queue. The queue is processed after unlock with the functions called
> in turn. A cheap variant for infrequent accesses of this is to
> start a 1 jiffie timer.

I don't understand how this would work. Taking a lock doesn't prevent
interrupts. And once you start playing with the KBD controller, how
can the ISR do anything but wait until you've finished? The problem is
the time spent playing with the KBD controller (most of it spent
waiting for it to become ready).

Regards,

Richard....
Permanent: rgooch@atnf.csiro.au
Current: rgooch@ras.ucalgary.ca

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