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

[Nils Tonnätt]

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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