Commit b9fa3df3 authored Oct 15, 2007 by Srivatsa Vaddagiri Committed by Ingo Molnar Oct 15, 2007

sched: group scheduler, fix latency

There is a possibility that because of task of a group moving from one
cpu to another, it may gain more cpu time that desired. See 
http://marc.info/?l=linux-kernel&m=119073197730334

 for details.

This is an attempt to fix that problem. Basically it simulates dequeue
of higher level entities as if they are going to sleep. Similarly it
simulate wakeup of higher level entities as if they are waking up from
sleep.

Signed-off-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>

parent fad095a7

kernel/sched_fair.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -727,6 +727,7 @@ static void enqueue_task_fair(struct rq rq, struct task_struct p, int wakeup)
		break;
		cfs_rq = cfs_rq_of(se);
		enqueue_entity(cfs_rq, se, wakeup);
		wakeup = 1;
		}
		}

		@@ -746,6 +747,7 @@ static void dequeue_task_fair(struct rq rq, struct task_struct p, int sleep)
		/* Don't dequeue parent if it has other entities besides us */
		if (cfs_rq->load.weight)
		break;
		sleep = 1;
		}
		}

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