On 30/04/14 14:39, Dietmar Eggemann wrote:
> From: Dietmar Eggemann <dietmar.eggem...@arm.com>
>
> There is no need to zero struct sched_group member cpumask and struct
> sched_group_power member power since both structures are already allocated
> as zeroed memory in __sdt_alloc().
>
> This patch has been tested with
> BUG_ON(!cpumask_empty(sched_group_cpus(sg))); and BUG_ON(sg->sgp->power);
> in build_sched_groups() on ARM TC2 and INTEL i5 M520 platform including
> CPU hotplug scenarios.
>
> Signed-off-by: Dietmar Eggemann <dietmar.eggem...@arm.com>
> ---
> kernel/sched/core.c | 2 --
> 1 file changed, 2 deletions(-)
>
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index 9cae286824bb..6bc51aebbf1b 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -5807,8 +5807,6 @@ build_sched_groups(struct sched_domain *sd, int cpu)
> continue;
>
> group = get_group(i, sdd, &sg);
> - cpumask_clear(sched_group_cpus(sg));
> - sg->sgp->power = 0;
> cpumask_setall(sched_group_mask(sg));
>
> for_each_cpu(j, span) {
>
there is also a discrepancy between build_sched_groups() and
build_overlap_sched_groups(). The latter one sets power and power_orig
to SCHED_POWER_SCALE * cpumask_weight(sg_span) (since c3decf0dfbc95
'sched: Always initialize cpu-power' and 8e8339a3a1069 'sched:
Initialize power_orig for overlapping groups').
So we could do the same in build_sched_groups(). IMHO, then the
appropriate check 'if (!group->sgp->power_orig)' in
sched_domain_debug_one() becomes superfluous.
-- Dietmar
Patch proposal against tip_sched_core.
-- >8 --
Subject: [PATCH] sched: Initialize sg->sgp->power and sg->sgp->power_orig for
non-overlapping groups
---
kernel/sched/core.c | 17 +++--------------
1 file changed, 3 insertions(+), 14 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 9cae286824bb..ccf9b811ba37 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -5206,18 +5206,6 @@ static int sched_domain_debug_one(struct sched_domain
*sd, int cpu, int level,
break;
}
- /*
- * 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");
- break;
- }
-
if (!cpumask_weight(sched_group_cpus(group))) {
printk(KERN_CONT "\n");
printk(KERN_ERR "ERROR: empty group\n");
@@ -5807,8 +5795,6 @@ build_sched_groups(struct sched_domain *sd, int cpu)
continue;
group = get_group(i, sdd, &sg);
- cpumask_clear(sched_group_cpus(sg));
- sg->sgp->power = 0;
cpumask_setall(sched_group_mask(sg));
for_each_cpu(j, span) {
@@ -5819,6 +5805,9 @@ build_sched_groups(struct sched_domain *sd, int cpu)
cpumask_set_cpu(j, sched_group_cpus(sg));
}
+ sg->sgp->power = SCHED_POWER_SCALE *
cpumask_weight(sched_group_cpus(sg));
+ sg->sgp->power_orig = sg->sgp->power;
+
if (!first)
first = sg;
if (last)
--
1.7.9.5
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