Messages in this thread |  | | Date | Mon, 28 Aug 2000 15:20:50 -0700 (PDT) | From | Linus Torvalds <> | Subject | RE: [patch] scheduler bugfix, SMP, 2.4.0-test7 |
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On Mon, 28 Aug 2000, Dimitris Michailidis wrote: > > On 28-Aug-2000 Ingo Molnar wrote: > > > the attached sched-2.4.0-test7-C1 patch fixes a 'missed wakeup' > > SMP-scheduler bug. > > +running_again: > + if (prev == idle_task(smp_processor_id())) > + goto out_unlock; > > Why don't you move the test for the idle task to the beginning of the > function so we don't need to take the run queue lock if prev is idle? There > is nothing to be done for idle tasks, we don't even need to set ->has_cpu.
No, that's not the right solution.
I think the right solution is to completely split up "schedule()" into two different functions (which just share 99% of the code), and basically have the idle thread call the _other_ schedule. The one that never does the test at all.
That way you know statically whether you are the idle thread or not. No test at all.
Linus
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