Tweak for RT kernel

gabtram · 2023-07-26 11:20:32

Hi to all,

i'm configuring my machine, i hope i'm in the final part of the standard configuration.
Now i'm having some problems with some vst, that are memory consumers.

I installed realtime privilege but not RTKIT.
I followed this https://wiki.linuxaudio.org/wiki/system … ime_kernel and install realtime and make some tweaks. Installed rtcqs python script to have a photo of my real time kernel.

These are my errors:
The scaling governor of one or more CPU's is not set to 'performance'. You can set the scaling governor to 'performance' with 'cpupower frequency-set -g performance' or 'cpufreq-set -r -g performance' (Debian/Ubuntu). See also https://wiki.linuxaudio.org/wiki/system … cy_scaling
Is necessary

Kernel 6.4.4-arch1-1 without 'threadirqs' parameter or real-time capabilities found. See also https://wiki.linuxaudio.org/wiki/system … ime_kernel
I followed the guidem can't find kernel file in boot and trying to unzip the kernel file and change the configuration maybe can't understand something

Kernel with Spectre/Meltdown mitigations found. This could have a negative impact on the performance of your system. See also https://wiki.linuxaudio.org/wiki/system … itigations
Is needed?

The following mounts should be avoided for audio purposes: /boot. See also https://wiki.linuxaudio.org/wiki/system … ilesystems
Can't understand this

Have you other hints?
I didn't want to make kernel tweaks cause the standard kernel of arch is just yet pretty well but if you use something very strong like vst3plugins via yabridge or ardour with 16 tracks (i have not yet installed ardour), for example, maybe is needed.

Thanks
Bye

Lone_Wolf · 2023-07-26 11:27:24

Guess you are not aware that there is a realtime kernel (linux-rt) in archlinux repos ?

I suggest you thoroughly read https://wiki.archlinux.org/title/Professional_audio a few times.

Last edited by Lone_Wolf (2023-07-26 11:27:35)

gabtram · 2023-10-17 07:32:41

Hi!!

How are you? Sorry for delayed response but my job overtake my arch progress!
Now i read many times the real time kernel page.
So i will install the RT kernerl patchset and configure the parameters like the page.

Actually i have almost 1 sec latency on my keyboard attached directly to the internal audio card of my HP and 400ms from the mic and guitar attached to my focusrite. I think is too much. When i register, for example, a guitar solo and have bass and drums on my hearphones the guitar arrive too late.

I have some question if you can help me:
1) the cpu freq scaling is really needed for hard real time?
2) I can install the kernel patchset from extra but after install the kernel how can i add to the boot loader? I read this on the RT patchset page "Note: Do not forget to add the newly installed kernel to your boot loader!"?
3) Is there some gui or command to set the buffer size and sample rate of pipewire-jack? Actually i use qpwgraph to handle the graphic chain and use Carla to test my lv2 and vst. I'm waiting to install arodur and zrythm and something else to start make my music finally.
4) Last but not least. Before i will make this updates, how can i freeze my arch linux and do a restore point to go back eventually?

After all of this i'd like to share my distro (there are 6 months of study and configurations) to the community. I think there so many distros for music but the best is tweaking you own starting from the base.

Thanks
Bye

Last edited by gabtram (2023-10-17 07:45:34)

Lone_Wolf · 2023-10-17 12:15:44

A1 :
Yes .
the linux kernel always sets a scaling governor, current default is schedutil. Setting the governor to performance improves performance a lot but does increase power drain. For RT pro audio you typically run time-ctritical stuff that needs a lot of computing power and the performance governor tends to be the best for that.

A2 : that depends entirely on the bootloader you use. Check its archwiki page.
(If you need help with it, starting a separate thread for it would be best).

A3: can't help with that. sorry.

A4: freezing archlinux tends to be a bad idea due to its rolling release model, but keeping a backup is always a good idea.
https://wiki.archlinux.org/title/System_backup shows several methods you can customize and there are ofcourse specialised programs for it (top link at the right of the page).

gabtram · 2023-10-17 16:15:50

Hi!

A1 :
Yes .
the linux kernel always sets a scaling governor, current default is schedutil. Setting the governor to performance improves performance a lot but does increase power drain. For RT pro audio you typically run time-ctritical stuff that needs a lot of computing power and the performance governor tends to be the best for that.

Ok thanks for the explanation. So i have to really use this. I have to read something more! The best is to do this passage before or after apply the pacth for real time kernel?

A2 : that depends entirely on the bootloader you use. Check its archwiki page.
(If you need help with it, starting a separate thread for it would be best).

Ok i will start another thread. I use grub

A4: freezing archlinux tends to be a bad idea due to its rolling release model, but keeping a backup is always a good idea.
https://wiki.archlinux.org/title/System_backup shows several methods you can customize and there are ofcourse specialised programs for it (top link at the right of the page).

What do you use? Which is you preferred program to backup?

Lone_Wolf · 2023-10-18 09:14:26

I have re-read the pro audio page and it looks like the system configuration section was written before the linux-rt kernel was added to repos.

You may not need to add the realtime kernel patch yourself, check mailing list post about linux-rt .

Backup :
I use rsync with a customized version of https://wiki.archlinux.org/title/Rsync# … tem_backup , but that doesn't suit everyone.

Many people select a tool and then try to use it to do the job they have in mind . I prefer to think about what the job needs to accomplish and search for tools that help with that.

gabtram · 2023-10-20 17:30:37

Lone_Wolf wrote:

I have re-read the pro audio page and it looks like the system configuration section was written before the linux-rt kernel was added to repos.
You may not need to add the realtime kernel patch yourself, check mailing list post about linux-rt .

Hi and really thanks fro your help!
Pardon me but maybe i have to learn some vocubulary about.
When you said "You may not need to add the realtime kernel patch yourself" it means that i can install pre-build package directly with pacman -S from Extra repo?

Lone_Wolf wrote:

IBackup :
I use rsync with a customized version of https://wiki.archlinux.org/title/Rsync# … tem_backup , but that doesn't suit everyone.
Many people select a tool and then try to use it to do the job they have in mind . I prefer to think about what the job needs to accomplish and search for tools that help with that.

Ok this is polite!
I've also thinked about follow the rsync scenario.
But fundamentally for this specific case i need something fast i can restore a backup if something went wrong during the RT patchset (installing from repo) or the CPU frequency changes.

Maybe the snapshot could be suitable in this case. I'd like to have something that one day i can use as a live cd in different pc.

So thanks again and have a nice weekend!
Bye

Arch Linux

#1 2023-07-26 11:20:32

Tweak for RT kernel

#2 2023-07-26 11:27:24

Re: Tweak for RT kernel

#3 2023-10-17 07:32:41

Re: Tweak for RT kernel

#4 2023-10-17 12:15:44

Re: Tweak for RT kernel

#5 2023-10-17 16:15:50

Re: Tweak for RT kernel

#6 2023-10-18 09:14:26

Re: Tweak for RT kernel

#7 2023-10-20 17:30:37

Re: Tweak for RT kernel

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