sched/deadline: Add SCHED_DEADLINE inheritance logic
Some method to deal with rt-mutexes and make sched_dl interact with
the current PI-coded is needed, raising all but trivial issues, that
needs (according to us) to be solved with some restructuring of
the pi-code (i.e., going toward a proxy execution-ish implementation).
This is under development, in the meanwhile, as a temporary solution,
what this commits does is:
- ensure a pi-lock owner with waiters is never throttled down. Instead,
when it runs out of runtime, it immediately gets replenished and it's
deadline is postponed;
- the scheduling parameters (relative deadline and default runtime)
used for that replenishments --during the whole period it holds the
pi-lock-- are the ones of the waiting task with earliest deadline.
Acting this way, we provide some kind of boosting to the lock-owner,
still by using the existing (actually, slightly modified by the previous
commit) pi-architecture.
We would stress the fact that this is only a surely needed, all but
clean solution to the problem. In the end it's only a way to re-start
discussion within the community. So, as always, comments, ideas, rants,
etc.. are welcome! :-)
Signed-off-by: Dario Faggioli <raistlin@linux.it>
Signed-off-by: Juri Lelli <juri.lelli@gmail.com>
[ Added !RT_MUTEXES build fix. ]
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1383831828-15501-11-git-send-email-juri.lelli@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 9ea1501..13c53a9 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1124,8 +1124,12 @@
* @dl_new tells if a new instance arrived. If so we must
* start executing it with full runtime and reset its absolute
* deadline;
+ *
+ * @dl_boosted tells if we are boosted due to DI. If so we are
+ * outside bandwidth enforcement mechanism (but only until we
+ * exit the critical section).
*/
- int dl_throttled, dl_new;
+ int dl_throttled, dl_new, dl_boosted;
/*
* Bandwidth enforcement timer. Each -deadline task has its
@@ -1359,6 +1363,8 @@
struct rb_node *pi_waiters_leftmost;
/* Deadlock detection and priority inheritance handling */
struct rt_mutex_waiter *pi_blocked_on;
+ /* Top pi_waiters task */
+ struct task_struct *pi_top_task;
#endif
#ifdef CONFIG_DEBUG_MUTEXES
diff --git a/include/linux/sched/rt.h b/include/linux/sched/rt.h
index 440434d..34e4ebe 100644
--- a/include/linux/sched/rt.h
+++ b/include/linux/sched/rt.h
@@ -35,6 +35,7 @@
#ifdef CONFIG_RT_MUTEXES
extern int rt_mutex_getprio(struct task_struct *p);
extern void rt_mutex_setprio(struct task_struct *p, int prio);
+extern struct task_struct *rt_mutex_get_top_task(struct task_struct *task);
extern void rt_mutex_adjust_pi(struct task_struct *p);
static inline bool tsk_is_pi_blocked(struct task_struct *tsk)
{
@@ -45,6 +46,10 @@
{
return p->normal_prio;
}
+static inline struct task_struct *rt_mutex_get_top_task(struct task_struct *task)
+{
+ return NULL;
+}
# define rt_mutex_adjust_pi(p) do { } while (0)
static inline bool tsk_is_pi_blocked(struct task_struct *tsk)
{