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Commit 16cfb1c0 authored by Nick Piggin's avatar Nick Piggin Committed by Linus Torvalds
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[PATCH] sched: reduce active load balancing 



Fix up active load balancing a bit so it doesn't get called when it shouldn't.
Reset the nr_balance_failed counter at more points where we have found
conditions to be balanced.  This reduces too aggressive active balancing seen
on some workloads.

Signed-off-by: default avatarNick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 81026794

kernel/sched.c

+10 −6
Original line number Diff line number Diff line
@@ -2021,6 +2021,7 @@ static int load_balance(int this_cpu, runqueue_t *this_rq, 


	schedstat_inc(sd, lb_balanced[idle]);



	sd->nr_balance_failed = 0;

	/* tune up the balancing interval */

	if (sd->balance_interval < sd->max_interval)

		sd->balance_interval *= 2;
@@ -2046,16 +2047,14 @@ static int load_balance_newidle(int this_cpu, runqueue_t *this_rq, 
	schedstat_inc(sd, lb_cnt[NEWLY_IDLE]);

	group = find_busiest_group(sd, this_cpu, &imbalance, NEWLY_IDLE);

	if (!group) {

		schedstat_inc(sd, lb_balanced[NEWLY_IDLE]);

		schedstat_inc(sd, lb_nobusyg[NEWLY_IDLE]);

		goto out;

		goto out_balanced;

	}



	busiest = find_busiest_queue(group);

	if (!busiest || busiest == this_rq) {

		schedstat_inc(sd, lb_balanced[NEWLY_IDLE]);

		schedstat_inc(sd, lb_nobusyq[NEWLY_IDLE]);

		goto out;

		goto out_balanced;

	}



	/* Attempt to move tasks */
@@ -2066,11 +2065,16 @@ static int load_balance_newidle(int this_cpu, runqueue_t *this_rq, 
					imbalance, sd, NEWLY_IDLE, NULL);

	if (!nr_moved)

		schedstat_inc(sd, lb_failed[NEWLY_IDLE]);

	else

		sd->nr_balance_failed = 0;



	spin_unlock(&busiest->lock);



out:

	return nr_moved;



out_balanced:

	schedstat_inc(sd, lb_balanced[NEWLY_IDLE]);

	sd->nr_balance_failed = 0;

	return 0;

}



/*