Ingo Molnar <[email protected]> wrote:
>
> ..
>
> this patch (ontop of the current -mm scheduler patchset) tweaks
> cpu_idle() semantics a bit: it changes the idle loops (that do
> preemption) to call the first schedule() unconditionally.
>
> the advantage is that as a result we dont have to set the idle thread's
> NEED_RESCHED flag in init_idle(), which in turn makes cond_resched()
> even more of an invariant: it can be called even from init code without
> it having any effect. A cond resched in the init codepath hangs
> otherwise.
>
> this patch, while having no negative side-effects, enables wider use of
> cond_resched()s. (which might happen in the stock kernel too, but it's
> particulary important for voluntary-preempt) (note that for now this
> patch only covers architectures that use kernel/Kconfig.preempt, but all
> other architectures will work just fine too.)
>
> --- linux/arch/x86_64/kernel/process.c.orig
> +++ linux/arch/x86_64/kernel/process.c
> @@ -162,6 +162,8 @@ EXPORT_SYMBOL_GPL(cpu_idle_wait);
> */
> void cpu_idle (void)
> {
> + set_tsk_need_resched(current);
> +
> /* endless idle loop with no priority at all */
> while (1) {
> while (!need_resched()) {
ia64 needed this treatment also to fix a hang during boot. u o me 3 hrs.
Are all the other architectures busted as well?
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