Commit c3decf0d authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

sched: Always initialize cpu-power 



Often when we run into mis-shapen topologies the balance iteration
fails to update the cpu power properly and we'll end up in /0 traps.

Always initialize the cpu-power to a semi-sane value so that we can
at least boot the machine, even if the load-balancer might not
function correctly.

Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/n/tip-3lbhyj25sr169ha7z3qht5na@git.kernel.org


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent c1174876

kernel/sched/core.c

+12 −1
Original line number Diff line number Diff line
@@ -5604,7 +5604,12 @@ static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level, 
			break;

		}



		if (!group->sgp->power) {

		/*

		 * Even though we initialize ->power to something semi-sane,

		 * we leave power_orig unset. This allows us to detect if

		 * domain iteration is still funny without causing /0 traps.

		 */

		if (!group->sgp->power_orig) {

			printk(KERN_CONT "\n");

			printk(KERN_ERR "ERROR: domain->cpu_power not "

					"set\n");
@@ -6075,6 +6080,12 @@ build_overlap_sched_groups(struct sched_domain *sd, int cpu) 
		if (atomic_inc_return(&sg->sgp->ref) == 1)

			build_group_mask(sd, sg);



		/*

		 * Initialize sgp->power such that even if we mess up the

		 * domains and no possible iteration will get us here, we won't

		 * die on a /0 trap.

		 */

		sg->sgp->power = SCHED_POWER_SCALE * cpumask_weight(sg_span);



		/*

		 * Make sure the first group of this domain contains the

kernel/sched/fair.c

+1 −1
Original line number Diff line number Diff line
@@ -3602,7 +3602,7 @@ void update_group_power(struct sched_domain *sd, int cpu) 
		} while (group != child->groups);

	}



	sdg->sgp->power = power;

	sdg->sgp->power_orig = sdg->sgp->power = power;

}



/*

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