sched: Fix migration thread runtime bogosity (8f618968) · Commits · 戴 / test

Make stop scheduler class do the same accounting as other classes, Migration threads can be caught in the act while doing exec balancing, leading to the below due to use of unmaintained ->se.exec_start. The load that triggered this particular instance was an apparently out of control heavily threaded application that does system monitoring in what equated to an exec bomb, with one of the VERY frequently migrated tasks being ps. %CPU PID USER CMD 99.3 45 root [migration/10] 97.7 53 root [migration/12] 97.0 57 root [migration/13] 90.1 49 root [migration/11] 89.6 65 root [migration/15] 88.7 17 root [migration/3] 80.4 37 root [migration/8] 78.1 41 root [migration/9] 44.2 13 root [migration/2] Signed-off-by:

Mike Galbraith <mgalbraith@suse.de> Signed-off-by:

Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1344051854.6739.19.camel@marge.simpson.net Signed-off-by:

Thomas Gleixner <tglx@linutronix.de>

kernel/sched/stop_task.c

+21 −1

Original line number	Diff line number	Diff line
		@@ -27,8 +27,10 @@ static struct task_struct pick_next_task_stop(struct rq rq)
		{
		struct task_struct *stop = rq->stop;

		if (stop && stop->on_rq)
		if (stop && stop->on_rq) {
		stop->se.exec_start = rq->clock_task;
		return stop;
		}

		return NULL;
		}
		@@ -52,6 +54,21 @@ static void yield_task_stop(struct rq *rq)

		static void put_prev_task_stop(struct rq rq, struct task_struct prev)
		{
		struct task_struct *curr = rq->curr;
		u64 delta_exec;

		delta_exec = rq->clock_task - curr->se.exec_start;
		if (unlikely((s64)delta_exec < 0))
		delta_exec = 0;

		schedstat_set(curr->se.statistics.exec_max,
		max(curr->se.statistics.exec_max, delta_exec));

		curr->se.sum_exec_runtime += delta_exec;
		account_group_exec_runtime(curr, delta_exec);

		curr->se.exec_start = rq->clock_task;
		cpuacct_charge(curr, delta_exec);
		}

		static void task_tick_stop(struct rq rq, struct task_struct curr, int queued)
		@@ -60,6 +77,9 @@ static void task_tick_stop(struct rq rq, struct task_struct curr, int queued)

		static void set_curr_task_stop(struct rq *rq)
		{
		struct task_struct *stop = rq->stop;

		stop->se.exec_start = rq->clock_task;
		}

		static void switched_to_stop(struct rq rq, struct task_struct p)

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