> Date: Thu, 4 Oct 2012 23:42:45 +0200
> From: Gregor Best <g...@ring0.de>
> Index: kern/kern_sched.c
> ===================================================================
> RCS file: /cvs/src/sys/kern/kern_sched.c,v
> retrieving revision 1.27
> diff -u -r1.27 kern_sched.c
> --- kern/kern_sched.c 10 Jul 2012 18:20:37 -0000 1.27
> +++ kern/kern_sched.c 4 Oct 2012 21:27:58 -0000
> @@ -158,18 +167,17 @@
>
> cpuset_add(&sched_idle_cpus, ci);
> cpu_idle_enter();
> - while (spc->spc_whichqs == 0) {
> - if (spc->spc_schedflags & SPCF_SHOULDHALT &&
> - (spc->spc_schedflags & SPCF_HALTED) == 0) {
> - cpuset_del(&sched_idle_cpus, ci);
> - SCHED_LOCK(s);
> - atomic_setbits_int(&spc->spc_schedflags,
> - spc->spc_whichqs ? 0 : SPCF_HALTED);
> - SCHED_UNLOCK(s);
> - wakeup(spc);
> - }
> - cpu_idle_cycle();
> +
> + if (spc->spc_schedflags & SPCF_SHOULDHALT &&
> + (spc->spc_schedflags & SPCF_HALTED) == 0) {
> + cpuset_del(&sched_idle_cpus, ci);
> + SCHED_LOCK(s);
> + atomic_setbits_int(&spc->spc_schedflags, SPCF_HALTED);
> + SCHED_UNLOCK(s);
> + wakeup(spc);
> }
> + cpu_idle_cycle();
> +
> cpu_idle_leave();
> cpuset_del(&sched_idle_cpus, ci);
> }
> @@ -222,14 +230,13 @@
I don't think changing the idle loop like this is ok. You want to
continue checking whether the runqueue is empty in between
cpu_idle_enter() and cpu_idle_leave().
