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

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.orgSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent c1174876
...@@ -5604,7 +5604,12 @@ static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level, ...@@ -5604,7 +5604,12 @@ static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level,
break; 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_CONT "\n");
printk(KERN_ERR "ERROR: domain->cpu_power not " printk(KERN_ERR "ERROR: domain->cpu_power not "
"set\n"); "set\n");
...@@ -6075,6 +6080,12 @@ build_overlap_sched_groups(struct sched_domain *sd, int cpu) ...@@ -6075,6 +6080,12 @@ build_overlap_sched_groups(struct sched_domain *sd, int cpu)
if (atomic_inc_return(&sg->sgp->ref) == 1) if (atomic_inc_return(&sg->sgp->ref) == 1)
build_group_mask(sd, sg); 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 * Make sure the first group of this domain contains the
......
...@@ -3602,7 +3602,7 @@ void update_group_power(struct sched_domain *sd, int cpu) ...@@ -3602,7 +3602,7 @@ void update_group_power(struct sched_domain *sd, int cpu)
} while (group != child->groups); } while (group != child->groups);
} }
sdg->sgp->power = power; sdg->sgp->power_orig = sdg->sgp->power = power;
} }
/* /*
......
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