Messages in this thread | | | Date | Tue, 29 Sep 2015 17:05:02 +0200 | From | Peter Zijlstra <> | Subject | Re: [RFC][PATCH 01/11] sched: Simplify INIT_PREEMPT_COUNT |
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On Tue, Sep 29, 2015 at 11:00:49AM -0400, Steven Rostedt wrote: > > [ Resend, with the Cc list back ]
You seem to have a hard time with these buttons today ;-)
> Hmm, I just looked closer and I'm wondering if this still works? > > We have: > > #ifdef CONFIG_PREEMPT_COUNT > #define PREEMPT_DISABLED (1 + PREEMPT_ENABLED) > #else > #define PREEMPT_DISABLED PREEMPT_ENABLED > #endif > > Now if we just remove the PREEMPT_ACTIVE from the INIT_PREEMPT_COUNT, > when CONFIG_PREEMPT_COUNT is not set, wouldn't a _cond_resched() in > boot up schedule?
Good point, PREEMPT_COUNT isn't required for voluntary preemption; when I tested the voluntary build nothing bad happened, but that could have been luck of course.
So what we can do is use an unconditional 1 for INIT_PREEMPT_COUNT, such that the init task will have a raised preempt_count() during boot, even on !PREEMPT_COUNT kernels.
But that means we cannot use INIT_PREEMPT_COUNT for init_task_preempt_count() and such like, as I wanted to. I'll make FORK_PREEMPT_COUNT for that instead.
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