[linux-audio-dev] A bit of an [ANN] :)

[james at dis-dot-dat.net]

On Mon, 10 Jul, 2006 at 12:39PM -0400, Dave Robillard spake thus:
> 
> 
> 
> james at dis-dot-dat.net wrote:
> 
> 
> >Howdy peeps.
> >
> >Not really much of a release, so not much fanfare, but in the
> >interests of sharing effort I give you...
> >
> >Powernap!
> >
> >http://dis-dot-dat.net/?item=code/powernap/
> >
> >If, like me, you need to drive an app from a Python interface,
> >powernap can help.  It's a small extension that switches to the
> >real-time scheduler and provides two handy sleep-like functions:
> >
> >nap() naps for a given number of milliseconds, timed with the RTC
> >
> >rnap() is a "rolling nap" that tries to make the time between calls
> >the given number of milliseconds.  A padding nap, if you will.
> >
> >It works for me and it might come in handy for someone else.
> 
> Nice, this will definitely come in handy for me.

Good!  I'm trying to see where I'm writing things that others can make
use of and make them fairly simple to reuse.
 
> Have you done any benchmarking on what kind of timing precision you can 
> get?

Nothing particularly concrete.  On my amd64 3700 sandiego, with other
apps running (normal desktop kinda stuff), aiming for a time between
sleeps of 310ms using rnap, I get a minimum gap of 308.34 and a
maximum of 312.48, so the range is about 5ms.  Standard deviation is
0.67, though and the average is 310.4.

Which is quite good, from Python, I think.

I think there might be a way for it to automatically compensate over
time for tending to be a little over, but 0.4ms probably isn't worth
it.

James
 
> -DR-
>