Re: [linux-audio-dev] introduction & ideas

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Subject: Re: [linux-audio-dev] introduction & ideas
From: Martijn Sipkema (msipkema_AT_sipkema-digital.com)
Date: Sat Mar 09 2002 - 19:30:54 EET


> > No, it doesn't accomplish this, but it can. The kernel will have to
> > support it, so Linux will have to gain accurate scheduling. In the
> > meantime I think getting the clock resolution on Intel from 10ms
> > down to 1ms will be sufficient in most cases.
>
> How likely is it that this will happen in mainstream Linux kernels?
> *heh*
>
> Then again, as it seems like the goal is to have properly working
> kernel preemption (required for real time, as well as high end SMP
> scalability), things like that actually start to become *useful* for
> real applications...

preemtible kernel patch is already in 2.5...

> After all, if games, audio applications and other multimedia
> applications are going to fight for the RTC, and then hog the
> scheduler with 1024+ Hz "wakeup rates", we have a problem.
>
> At that point, it would be a lot more efficient if those applications
> could just use high resolution software timers (driven by the
> programmable system timer, something like in KURT, AFAIK), programmed
> to wake threads up *only when required*, as opposed to "at an
> arbitrary rate, just high enough to do the job".

I think IBM had a patch that did this because the overhead of getting
interrupted by the system timer every 10ms was too large running a lot
of linux kernel images on their servers.

> Is this relevant to other applications than "professional MIDI
> applications"?

I think so.

> > I really don't think that's necessary. A <<ms accurate time should
> > be sufficient.
>
> Well, it all depends on your definition of "correct MIDI timing"...

<<ms

--martijn


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