[64studio-devel] [Jackit-devel] CPU load reading too high on dual-core and SMP machines?

[Daniel James]

Hi Paul,

> JACK doesn't report CPU load. it reports "DSP load"

Both qjackctl and jamin label this figure as CPU load, which is probably 
where we got confused. Ardour gets it right, of course :-)

 > in reality, you can only get up to
> about 80-85% DSP load before things fall apart

We've had a report of a successful test at 95% for two hours, no xruns.

> any normal measure
> of CPU load (top or any other system monitor) would have been reading
> 100% long before that.

We're seeing the opposite on dual-core and dual processor machines; the 
'average' figure from top is half that reported by jack.

> Which wall clock
> are you using with JACK (gettimeofday, TSC, HPET etc.) ?

Our latest 2.6.18 kernel packages have CONFIG_HPET_TIMER=y but this is 
preventing certain systems from booting, so unless there's a fix soon 
we'll have to disable HPET by default. Is there a way to get jackd to 
report which clock source it is actually using? I couldn't see anything 
relevant in the verbose message output.

Cheers!

Daniel