Re: Periodic rant about SCHED_ULE

From: George Mitchell <>
Date: Thu, 23 Mar 2023 18:55:22 UTC
On 3/23/23 06:03, David Chisnall wrote:
> On 22/03/2023 18:03, George Mitchell wrote:
>> Rebuilding the kernel is the only way I know.  In an ideal world, the
>> scheduler would be a loadable kernel module (if that's even possible),
> Solaris supports multiple schedulers, as I believe does Linux, but I 
> think in both cases it's a boot-time option.  It's been too long since I 
> looked at the early boot order to know if there's anything that handles 
> linking the loader-provided modules that depends on any scheduler data 
> structures.  Doing that audit and ensuring that there aren't would be 
> the first step.  From there, it should be mostly build-system 
> infrastructure to allow building the two schedulers as modules and 
> switching between them at boot.
> Allowing switching schedulers after boot time is a much harder problem. 
> I know some microkernels have done it, but even there (where the 
> scheduler is a separate service) it's far from easy.
> David

I never expected to be able to switch schedulers after boot time, but
I assume even switching at boot time would require the scheduler to be
a kernel loadable module.                                   -- George