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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: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/n/tip-3lbhyj25sr169ha7z3qht5na@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Peter Zijlstra 2012-05-31 12:05:32 +02:00 committed by Ingo Molnar
parent c117487687
commit c3decf0dfb
2 changed files with 13 additions and 2 deletions
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13
kernel/sched/core.c
View File

@ -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

2
kernel/sched/fair.c
View File

@ -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;
}
/*