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authorPeter Zijlstra <a.p.zijlstra@chello.nl>2012-05-31 12:05:32 +0200
committerIngo Molnar <mingo@kernel.org>2012-06-06 16:52:27 +0200
commitc3decf0dfbc95736b7c0ab68fa4e5854c4734da9 (patch)
treec21748af2b4c7e4b738cefd2076c1ccc6ed2c664 /kernel
parentc1174876874dcf8986806e4dad3d7d07af20b439 (diff)
downloadlinux-c3decf0dfbc95736b7c0ab68fa4e5854c4734da9.tar.bz2
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>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/sched/core.c13
-rw-r--r--kernel/sched/fair.c2
2 files changed, 13 insertions, 2 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 781acb91a50a..725ee7c1c8cf 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -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
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 54cbaa4e7b37..c9fd6d673d05 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -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;
}
/*