[PlanetCCRMA] max-user-freq in rc.local

Fernando Lopez-Lezcano nando@ccrma.Stanford.EDU
Sun Sep 23 12:29:02 2007

On Sun, 2007-09-23 at 04:01 -0700, Tracey Hytry wrote:
> Hi, I have fedora 6 and 7 on my machine and decided I am going to boot 
> into fedora 7 from now on.  I used to stay in fc6 most of the time, doing 
> updates to fedora 7 via chroot.
> I've done some testing on 7 and found I like it a lot.  It seems to be 
> take my usual torture test of dragging a 1280x1024 wine session of world 
> of warcraft (openGL) around the screen while checking the audio system
> (jack at 5.8msec latency(128/2 on audiophile 2496) running a hydrogen demo).  
> I used the rtlimits trick of of giving realtime to a group that I'm in, 
> but not the one that the user of the wine session is in.
> So,
> I had noticed that "/proc/sys/dev/rtc/max-user-freq" on another machine 
> was set to 64 and went over to my fedora 6/7 box to get the "/etc/rc.local" 
> thing where I set the max-user-freq to 1024.  Since I was now running 
> fedora 7 I checked "rc.local" and saw that I hadn't set it up.  So I go 
> to /proc/sys/dev onthe f7 box and find there is no rtc.  Instead I find 
> that I have a "/proc/sys/dev/hpet/max-user-freq" that says it's set to 64.
> Now, after all of the above intro, I have a question.
> Should I change the hpet/max-user-freq from 64 to 1024?

Hmmm, good question that I don't really know the answer to (but I'd like
to know). I guess it depends on whether any of the software actually
uses the hpet timer directly. The one I can think of as being important
would be alsa. But I really don't know what the timing source (for midi
specially) is these days. 

I imagine it does not depend on rtc (hpet now?) any more but I'm not
sure. Also, I'm not even sure if hpet is available on all hardware. The
newest kernels have high resolution timers and a tickless system but I
don't know whether alsa uses them for its timing. Any alsa experts
reading this?

-- Fernando