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authorIngo Molnar <mingo@elte.hu>2005-06-28 10:40:42 -0400
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-06-28 17:56:51 -0400
commitf340c0d1a3f40fdcba69cd291530a4debc58748f (patch)
tree22fca5983aff6ce2aa7d4ede0b031666dfe1f28d /kernel/sched.c
parent082cf69eb82681f4eacb3a5653834c7970714bef (diff)
[PATCH] Tweak idle thread setup semantics
This patch tweaks idle thread setup semantics a bit: instead of setting NEED_RESCHED in init_idle(), we do an explicit schedule() before calling into cpu_idle(). 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) Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'kernel/sched.c')
-rw-r--r--kernel/sched.c9
1 files changed, 8 insertions, 1 deletions
diff --git a/kernel/sched.c b/kernel/sched.c
index e2b0d3e4dd06..5f2182d42241 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -4166,6 +4166,14 @@ void show_state(void)
4166 read_unlock(&tasklist_lock); 4166 read_unlock(&tasklist_lock);
4167} 4167}
4168 4168
4169/**
4170 * init_idle - set up an idle thread for a given CPU
4171 * @idle: task in question
4172 * @cpu: cpu the idle task belongs to
4173 *
4174 * NOTE: this function does not set the idle thread's NEED_RESCHED
4175 * flag, to make booting more robust.
4176 */
4169void __devinit init_idle(task_t *idle, int cpu) 4177void __devinit init_idle(task_t *idle, int cpu)
4170{ 4178{
4171 runqueue_t *rq = cpu_rq(cpu); 4179 runqueue_t *rq = cpu_rq(cpu);
@@ -4183,7 +4191,6 @@ void __devinit init_idle(task_t *idle, int cpu)
4183#if defined(CONFIG_SMP) && defined(__ARCH_WANT_UNLOCKED_CTXSW) 4191#if defined(CONFIG_SMP) && defined(__ARCH_WANT_UNLOCKED_CTXSW)
4184 idle->oncpu = 1; 4192 idle->oncpu = 1;
4185#endif 4193#endif
4186 set_tsk_need_resched(idle);
4187 spin_unlock_irqrestore(&rq->lock, flags); 4194 spin_unlock_irqrestore(&rq->lock, flags);
4188 4195
4189 /* Set the preempt count _outside_ the spinlocks! */ 4196 /* Set the preempt count _outside_ the spinlocks! */