Messages in this thread | | | From | Valentin Schneider <> | Subject | Re: [PATCH] sched: Tweak default dynamic preempt mode selection | Date | Mon, 08 Nov 2021 11:17:38 +0000 |
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On 06/11/21 05:40, Mike Galbraith wrote: > On Fri, 2021-11-05 at 10:40 +0000, Valentin Schneider wrote: >> Commit c597bfddc9e9 ("sched: Provide Kconfig support for default dynamic >> preempt mode") changed the selectable config names for the preemption >> model. This means a config file must now select >> >> CONFIG_PREEMPT_BEHAVIOUR=y >> >> rather than >> >> CONFIG_PREEMPT=y >> >> to get a preemptible kernel. This means all arch config files need to be >> updated - right now arm64 defconfig selects CONFIG_PREEMPT=y but ends up >> with CONFIG_PREEMPT_NONE_BEHAVIOUR=y. >> >> Instead, have CONFIG_*PREEMPT be the selectable configs again, and make >> them select their _BEHAVIOUR equivalent if CONFIG_PREEMPT_DYNAMIC is set. > > > Is there any way to get to PREEMPT_RT in the first selection again as > well? I had created a behavior entry for RT (below) and inverted the > dependency to make it appear in the initial selection again, but that's > clearly not gonna fly. > > Starting with a 5.15 config, to select RT you currently must first > select a model you don't want, then reject PREEMPT_DYNAMIC and you'll > be offered the full menu of models immediately. With your patch added, > that became worse. After rejecting PREEMPT_DYNAMIC, I had to go > through new 5.15+ options before finally being offered the full menu. >
Do you mean at the syncconfig step? I've only really played with upstream arm64 / x86 defconfigs and didn't have to fight with any prompts, though yes for x86 the default-y PREEMPT_DYNAMIC makes it a bit annoying to select PREEMPT_RT.
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