Re: [Jack-Devel] jack dsp load calculation

On Tue, December 29, 2015 2:54 am, Kjetil Matheussen wrote:
> I don't know the kernel very well, but 4-10 percentage points sounds
> a lot for kernel house keeping.

Speaking of percentage differences in the abstract is not very useful.
Check the period size in use and convert that percentage difference to an
actual time difference to see whether the time difference is reasonable.
Latency variations I have seen quoted are in the high three digit
milliseconds to over a second for a kernel with no preemption, multiple
tens of milliseconds for voluntary preempt (but not hard limited), and
around one millisecond or less for full RT patches.

Keep in mind that a lot of motherboards use system management mode for
things like checking temperature, and SMM preempts even the kernel, so no
matter which kernel variant you use that time is lost.  The only thing you
can do is try to disable options in the BIOS to reduce the time spent in
SMM.

--
Chris Caudle

1451419931.13491_0.ltw:2,a <283d71f9cbeb5b25f52de1cad28a394d.squirrel at email dot powweb dot com>