[PlanetCCRMA] jackfreq 0.2.0

Martin Tarenskeen m.tarenskeen at kpnmail.nl
Sun Mar 1 12:30:52 PST 2020


Sounds interesting, I am going to give it a try. Is there a reason why it 
can't be offered to the normal Fedora repository, instead of PlanetCCRMA? 
That would be preferable, I think?


On Sun, 1 Mar 2020, Oleg Samarin wrote:

> Hi, All!
> I'd like to add a new package 'jackfreq' to the CCRMA repository.
> A lot of time ago Robin Gareus created jackfreqd: a daemon that changes
> the CPU frequency based on the jack DSP load. It used the 'userspace'
> cpu scaling governor.
> Then the newer CPUs appeared. The newer Linux kernel started using the
> 'intel_pstate' cpu scaling driver that supports a lot of features of
> the new cpus, including turbo bust. CPU frequency raises automaticaly
> when CPU is loaded and it returns back to the minimal value (usually
> 800mhz) when CPU is idle.
> But when using jack audio connection kit with several application
> threads, these threads are spreading across cpu cores, and cpu load is
> not sufficient for required rasing cpu frequency. It causes XRuns and
> the sound distortion.
> Unfortunately, the intel_pstate driver does not provide the 'userspace'
> governor required by jackfreqd. provides only two cpu scaling
> governors: 'powersave' - cpu itself selectss the frequency to work at -
> and 'performance, that locks CPU frequency at the hihest value
> available for 100% load on all cores. Most of linux audio tuning guides
> recommend to set governor to 'performance' all the time.
> But there are some disadvantages of this solution.
> 1. The cpu frequency is high even this is not necessary.
> 2. It causes high CPU voltage that lowers the CPU time to live.
> 3. It is unable to achieve tfor he maximum frequency for single-core
> load, that is usually higher then all cores. It may be not desirable if
> the computer is not dedicated for audio tasks and there are some
> single-thread applications that are preferred to run at the higest
> single-core frequency.
> The resolution of this chalange: to set the 'powersave' governor when
> no jack audio alpplications are active and switch it to 'performance'
> when jack DSP load is exceeds a configured threshold (50% by default).
> The new version of jackfreqd makes this automatically when the
> 'intel_pstate' driver is active. It continues to use the old
> 'userspace' governor for elder drivers.
> The sourcecode of jackfreqd is available at
> https://github.com/oleg68/jackfreqd
> Both rpm and source rpm packages are available rpm-based linux
> distributions (I've tested it with Fedora 31).
> https://github.com/oleg68/jackfreqd/releases/download/v0.2.0/jackfreq-0.2.0-0.fc31.src.rpm
> https://github.com/oleg68/jackfreqd/releases/download/v0.2.0/jackfreq-0.2.0-0.fc31.x86_64.rpm
> Oleg Samarin.
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