Messages in this thread | | | From | "Mitchell Erblich" <> | Subject | QUESTION: RT & SCHED & fork: ?MISSING EQUIV of task_new_fair for RT tasks. | Date | Tue, 14 Aug 2007 12:28:02 -0700 |
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Group, Ingo Molnar, etc,
Why does the rt sched_class contain fewer elements than fair? missing is the RT for .task_new.
called by do_fork(): fork.c , which calls wake_up_new_task() via if (!(clone_flags & CLONE_STOPPED)) wake_up_new_task(p, clone_flags);
which is in sched.c and calls if (!p->sched_class->task_new ||
and p->sched_class->task_new(rq, p, now);
sched_rt.c: static struct sched_class rt_sched_class __read_mostly = { 217 .enqueue_task = enqueue_task_rt, 218 .dequeue_task = dequeue_task_rt, 219 .yield_task = yield_task_rt, 220 221 .check_preempt_curr = check_preempt_curr_rt, 222 223 .pick_next_task = pick_next_task_rt, 224 .put_prev_task = put_prev_task_rt, 225 226 .load_balance = load_balance_rt, 227 228 .task_tick = task_tick_rt, 229 };
sched_fair.c: struct sched_class fair_sched_class __read_mostly = { 1075 .enqueue_task = enqueue_task_fair, 1076 .dequeue_task = dequeue_task_fair, 1077 .yield_task = yield_task_fair, 1078 1079 .check_preempt_curr = check_preempt_curr_fair, 1080 1081 .pick_next_task = pick_next_task_fair, 1082 .put_prev_task = put_prev_task_fair, 1083 1084 .load_balance = load_balance_fair, 1085 1086 .set_curr_task = set_curr_task_fair, 1087 .task_tick = task_tick_fair, 1088 .task_new = task_new_fair, 1089 }; 1090
The missing rt equivalent item is: /* 1014 * Share the fairness runtime between parent and child, thus the 1015 * total amount of pressure for CPU stays equal - new tasks 1016 * get a chance to run but frequent forkers are not allowed to 1017 * monopolize the CPU. Note: the parent runqueue is locked, 1018 * the child is not running yet. 1019 */ 1020 static void task_new_fair(struct rq *rq, struct task_struct *p) 1021 {
Mitchell Erblich
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