Messages in this thread Patch in this message | | | Date | Wed, 30 Apr 2014 14:46:55 +0100 | From | Dietmar Eggemann <> | Subject | Re: [PATCH] sched: Do not zero sg->cpumask and sg->sgp->power in build_sched_groups |
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On 30/04/14 14:39, Dietmar Eggemann wrote: > From: Dietmar Eggemann <Dietmar.Eggemann@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.eggemann@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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