This patch adds an RT overload accounting system. When a runqueue has more than one RT task queued, it is marked as overloaded. That is that it is a candidate to have RT tasks pulled from it. Along with the rt_overload counter (number of overloaded runqueues) a bit mask of overloaded runqueues with RT tasks is set. Signed-off-by: Steven Rostedt --- kernel/sched_rt.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) Index: linux-test.git/kernel/sched_rt.c =================================================================== --- linux-test.git.orig/kernel/sched_rt.c 2007-10-19 12:34:46.000000000 -0400 +++ linux-test.git/kernel/sched_rt.c 2007-10-19 12:35:58.000000000 -0400 @@ -25,10 +25,23 @@ static void update_curr_rt(struct rq *rq curr->se.exec_start = rq->clock; } +#ifdef CONFIG_SMP +static __cacheline_aligned_in_smp atomic_t rt_overload; +static cpumask_t rto_cpumask; +#endif /* CONFIG_SMP*/ + static inline void inc_rt_tasks(struct task_struct *p, struct rq *rq) { if (rt_task(p)) rq->rt_nr_running++; +#ifdef CONFIG_SMP + if (rq->rt_nr_running == 2) { + cpu_set(rq->cpu, rto_cpumask); + /* Make sure this cpu is visible on rt_overloads */ + smp_wmb(); + atomic_inc(&rt_overload); + } +#endif } static inline void dec_rt_tasks(struct task_struct *p, struct rq *rq) @@ -37,6 +50,12 @@ static inline void dec_rt_tasks(struct t WARN_ON(!rq->rt_nr_running); rq->rt_nr_running--; } +#ifdef CONFIG_SMP + if (rq->rt_nr_running == 1) { + atomic_dec(&rt_overload); + cpu_clear(rq->cpu, rto_cpumask); + } +#endif } static void enqueue_task_rt(struct rq *rq, struct task_struct *p, int wakeup) -- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/