Kernel-preempt

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1

By the last update of my Leap 15.2 box, the kernel was updated to kernel “kernel-preempt”.
What is the meaning of such a name change?

2

I think, kernel-preempt was installed besides kernel-default.

You are not the first one.

Delete the preempt and use the deafult kernel.

Kernel-preempt:

The kernel for arm64 and x86_64 architectures that supports CONFIG_PREEMPT. Its
main purpose is to serve workloads with a higher demand on smaller latencies
than the default kernel in average.

3

Thanks.
I suppose, if I want to use the default kernel, I’ll also have to remove the nvidia-gfxG05-kmp-preempt and virtualbox-kmp-preempt packages, won’t I?

4

Yes and install the xxxxx-default packages.

5

The xxx-default packages stayed installed by the last update.
Shall removing the xxx-preempt packages do the trick?

6

I’m surprised that it’s so easy to convert from cooperative to preemptive. I think there has been maybe two threads over the past 15 years likely in the Development Forums related to this characteristic.

All systems should be “cooperative” by default and any time it’s been mentioned in the past I’m pretty sure it required special compilation. Apparently not totally true nowadays if you can simply pass a boot parameter?

https://www.geeksforgeeks.org/difference-between-preemptive-and-cooperative-multitasking/

TSU

7

Post:

zypper se -si kernel nvidia
8

Ooops …


 # uname -a
Linux xxx 5.3.18-lp152.57-preempt #1 SMP PREEMPT Fri Dec 4 07:27:58 UTC 2020 (7be5551) x86_64 x86_64 x86_64 GNU/Linux
 #

In the boot configuration, I always had simply “openSUSE Leap 15.2” setup …

  • Because I was testing a Kernel patch, I installed the “kernel-syms” package for the build and, that pulled in “kernel-preempt-devel” …
  • Then “virtualbox-kmp-preempt” got pulled in which, pulled “kernel-preempt” in …
  • “kernel-preempt” is at the top of the list, and therefore, the “openSUSE Leap 15.2” setting in the Bootloader uses that … :frowning:
  • It seems that, neither the patch openSUSE-2020-2161 nor the patch openSUSE-2020-2180 caused this behaviour …

[HR][/HR]It seems that, I have some housekeeping to do …

  • Grrr!!!
9

I have been forced to “zypper rm kernel-preempt” on every OpenSUSE machine that I have access to. Many laptops lost network connectivity when kernel-preempt was the default.
Fortunately - the second grub menu entry was for kernel-default which restored network connectivity.

10

Could someone tell me if it is possible to reverse back to default as I have the feeling the preemptive kernel is slower at boot and more buggy than the default (NFS seems to be slower when moving big files) ?

I moved all the preempt$ files to old folder in /boot folder.
I just want to know if I modify the symlink vmlinuz and initrd to default they will keep pointing to the default kernel even if updating ?

Is there another way to switch the symlinks to default kernel ?
Yast doesn’t seem to modify them.

11

Hi
I would select the default kernel at boot, then just remove the preempt kernel via zypper.