[LAU] realtime kernel

[Mulyadi Santosa]

Hi...
> Hi everyone!
>   Short question only: If I compile a realtime kernel, with Ingo's patches, do 
> I need to set the timer to 1000Hz. 
It still worths to use 1000 Hz even if you use realtime kernel. real 
time kernel, AFAIK, makes interrupts management (especially timer) more 
fluid (read: fast). However, that also depends on the timer granularity 
itself. That's why using 1000Hz is important: finer granularity.

If you care about power consumption, enable no_hz so clock ticks are 
skipped whenever no timers need to be handled at certain time. This is 
to compensate the fact that higher HZ means more time spent to handle 
interrupts.

In my experiment (for still unpublished article), making HZ higher makes 
UI (User Interface)  somewhat more responsible to mouse movement/click 
and keyboard press. This is probably due to the way signal is handled in 
Linux: they are piggybacking kernel-to-user space code path

And don't forget to use full preemption. So the full recipe is:
1000HZ + no_hz + full preemption

AFAIK, most MIDI applications now use RTC, so they don't rely on HZ 
granularity. But still, using HZ=1000 bring advantage for another aspect.


> Or is it best to do so. My system is about 
> 2 and a half years old athlon 2500+ CPU 1.8gHz.
>   
Single CPU single core, then? Make sure not to compile your kernel for 
SMP, that will make your kernel a bit smaller and somewhat faster.

Hope this helps.

regards,

Mulyadi