[LAD] Timers, hpet, hrtimer

Paul Davis paul at linuxaudiosystems.com
Tue Nov 10 19:45:52 UTC 2009

On Tue, Nov 10, 2009 at 1:33 PM,  <fons at kokkinizita.net> wrote:

> What I don't see is how e.g. MIDI generators can use it
> in this way to get accurate event timing. Either they are
> spinning (evil), or they'd need a system call anyway, and
> it that case they should use kernel services instead.

you're confusing two different ways of interacting with the HPET.

as jussi described, the HPET consists of both a free-running timer,
and schedulable timers that cause interrupts. the comments earlier in
thread regarding MIDI scheduling rely on the second part of the HPET,
not the first, and yes, user space would interact with them via normal
system calls like usleep().

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