[PlanetCCRMA] preempt=full in 5.16.0 (was: Akmod for the realtime kernel)

[Be]

Oh great news! I installed the kernel following the instructions on the
wiki:
https://fedoraproject.org/wiki/Test_Day:2022-01-23_Kernel_5.16_Test_Week

Now, how do I configure Pipewire to get realtime priority without
needing to manually run chrt? The Pipewire documentation is unclear...
https://gitlab.freedesktop.org/pipewire/pipewire/-/issues/2024

If we could get preempt=full and Pipewire with realtime priority by
default in upstream Fedora, that would be wonderful. Just plug and play
for realtime audio... well, I can dream.

On 1/24/22 16:10, Nils Tonnätt wrote:
> Hi,
>
> I checked out the upcoming kernel for Fedora 35:
>
> [    0.069100] Kernel command line:
> BOOT_IMAGE=(hd2,gpt2)/boot/vmlinuz-5.16.2-200.fc35.x86_64
> root=UUID=7812bc02-a2ea-4335-bc7b-636e1612841a ro rhgb quiet
> threadirqs preempt=full
> [    0.069632] Dynamic Preempt: full
>
> This week is kernel test week. So probably next week, we will have a
> kernel with dynamic preemption in Fedora.
>
> Best,
> Nils
>
>
> Am Di, 11. Jan 2022 um 17:55:04 -0800 schrieb Fernando Lopez-Lezcano
> <nando at ccrma.Stanford.EDU>:
>> On 1/10/22 3:06 PM, Fernando Lopez-Lezcano wrote: ...
>>
>>     ==== System A: kernel 5.14.8-200.1.motu.fc34.ccrma (preempt=full)
>>
>> I did a local build for fc34 of the latest Koji 5.16.0 Fedora source
>> package and installed it in my "System B". At least in that source
>> package CONFIG_PREEMPT_DYNAMIC is set to "y" (yay!, cross fingers it
>> stays that way!) and I can switch to preempt=full when booting
>> without any further tweaks. The kernel no longer prints the status
>> when booting, but "cat /sys/kernel/debug/check/preempt" confirms the
>> system is in preempt=full state. The latency numbers I see on my
>> first test and reported by cyclictest are not quite as good as
>> "System A" (running 5.14.8), but they are good. -- Fernando PS:
>> Anyone knows how to convince pipewire to let go of an audio
>> interface? That is, not use it anymore? I'm trying the Motu driver
>> and I would like to remove the snd_usb_audio kernel driver to reload
>> the motu driver - long story of why, and it is not easy as the driver
>> is in use by pipewire...
>
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