Re: ULE realtime scheduler advice needed

On Tue, 22 Nov 2022 22:38:04 +0100
Hans Petter Selasky <hps@selasky.org> wrote:

> On 11/22/22 20:28, mike tancsa wrote:
> > On 11/17/2022 11:47 PM, Hans Petter Selasky wrote:
> >> Hi,
> >>
> >> I'm doing some work with audio and have noticed some problems with the 
> >> ULE scheduler. I have a program that generate audio based on 
> >> key-presses. When no keys are pressed, the load is near 0%, but as 
> >> soon as you start pressing keys, the load goes maybe to 80% of a CPU 
> >> core. This program I run with rtprio 8 xxx. The issue I observe or 
> >> hear actually, is that it takes too long until the scheduler grasps 
> >> that this program needs it's own CPU core and stops time-sharing the 
> >> program. When I however use cpuset -l xxx rtprio 8 yyy everything is 
> >> good, and the program outputs realtime audio in-time.
> >>
> >> Or is this perhaps a CPU frequency stepping issue?
> >>
> >> Any advice on where to look?
> >>
> > A long shot, but I am curious if by chance you have hwpstate_intel for 
> > your cpu frequency driver. If so, does setting 
> > dev.hwpstate_intel.0.epp=0 make any difference ?
> > 
> 
> Yes, I have four of those, set to 50 by default. Let me try.
> 
> --HPS

FYI: I habitally run below manually (as root) when I'm on AC powerline.

sysctl -aN | fgrep dev.hwpstate | fgrep epp | while read OID ; do ; \
sysctl ${OID}=0 ; done

-- 
Tomoaki AOKI    <junchoon@dec.sakura.ne.jp>