On 01/17/2014 03:09 PM, Peter Zijlstra wrote:
On Fri, Jan 17, 2014 at 10:04:04AM +0100, Daniel Lezcano wrote:
- schedstat_inc(rq, sched_goidle);
+#ifdef CONFIG_SMP
- /* Trigger the post schedule to do an idle_enter for CFS */
- rq->post_schedule = 1;
+#endif
- return rq->idle;
Urgh, that retains the stupid idle crap like it is.
I've not yet tested this, but is there a reason something like the below couldn't work?
I tested it by running hackbench and it seems to work as expected.
Subject: sched: Clean up idle task SMP logic From: Peter Zijlstra peterz@infradead.org Date: Fri Jan 17 14:54:02 CET 2014
The idle post_schedule hook is just a vile waste of time, fix it proper.
Signed-off-by: Peter Zijlstra peterz@infradead.org
kernel/sched/fair.c | 5 +++-- kernel/sched/idle_task.c | 21 ++++++--------------- 2 files changed, 9 insertions(+), 17 deletions(-)
Index: linux-2.6/kernel/sched/fair.c
--- linux-2.6.orig/kernel/sched/fair.c +++ linux-2.6/kernel/sched/fair.c @@ -2416,7 +2416,8 @@ void idle_exit_fair(struct rq *this_rq) update_rq_runnable_avg(this_rq, 0); }
-#else +#else /* CONFIG_SMP */
- static inline void update_entity_load_avg(struct sched_entity *se, int update_cfs_rq) {} static inline void update_rq_runnable_avg(struct rq *rq, int runnable) {}
@@ -2428,7 +2429,7 @@ static inline void dequeue_entity_load_a int sleep) {} static inline void update_cfs_rq_blocked_load(struct cfs_rq *cfs_rq, int force_update) {} -#endif +#endif /* CONFIG_SMP */
static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se) { Index: linux-2.6/kernel/sched/idle_task.c =================================================================== --- linux-2.6.orig/kernel/sched/idle_task.c +++ linux-2.6/kernel/sched/idle_task.c @@ -13,18 +13,8 @@ select_task_rq_idle(struct task_struct * { return task_cpu(p); /* IDLE tasks as never migrated */ }
-static void pre_schedule_idle(struct rq *rq, struct task_struct *prev) -{
- idle_exit_fair(rq);
- rq_last_tick_reset(rq);
-}
-static void post_schedule_idle(struct rq *rq) -{
- idle_enter_fair(rq);
-} #endif /* CONFIG_SMP */
- /*
*/
- Idle tasks are unconditionally rescheduled:
@@ -37,8 +27,7 @@ static struct task_struct *pick_next_tas { schedstat_inc(rq, sched_goidle); #ifdef CONFIG_SMP
- /* Trigger the post schedule to do an idle_enter for CFS */
- rq->post_schedule = 1;
- idle_enter_fair(rq); #endif return rq->idle; }
@@ -58,6 +47,10 @@ dequeue_task_idle(struct rq *rq, struct
static void put_prev_task_idle(struct rq *rq, struct task_struct *prev) { +#ifdef CONFIG_SMP
- idle_exit_fair(rq);
- rq_last_tick_reset(rq);
+#endif }
static void task_tick_idle(struct rq *rq, struct task_struct *curr, int queued) @@ -101,8 +94,6 @@ const struct sched_class idle_sched_clas
#ifdef CONFIG_SMP .select_task_rq = select_task_rq_idle,
.pre_schedule = pre_schedule_idle,
.post_schedule = post_schedule_idle, #endif
.set_curr_task = set_curr_task_idle,