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[PATCH] sched: null domains

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Fix the last 2 places that directly access a runqueue's sched-domain and
assume it cannot be NULL.

That allows the use of NULL for domain, instead of a dummy domain, to signify
no balancing is to happen.  No functional changes.

Signed-off-by: Nick Piggin <nickpiggin@yahoo.com.au>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Nick Piggin 2005-06-25 14:57:24 -07:00 committed by Linus Torvalds
parent 4866cde064
commit 41c7ce9ad9
1 changed files with 21 additions and 15 deletions
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36
kernel/sched.c
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@ -2579,11 +2579,15 @@ void scheduler_tick(void)
#ifdef CONFIG_SCHED_SMT
static inline void wake_sleeping_dependent(int this_cpu, runqueue_t *this_rq)
{
struct sched_domain *sd = this_rq->sd;
struct sched_domain *tmp, *sd = NULL;
cpumask_t sibling_map;
int i;
if (!(sd->flags & SD_SHARE_CPUPOWER))
for_each_domain(this_cpu, tmp)
if (tmp->flags & SD_SHARE_CPUPOWER)
sd = tmp;
if (!sd)
return;
/*
@ -2624,13 +2628,17 @@ static inline void wake_sleeping_dependent(int this_cpu, runqueue_t *this_rq)
static inline int dependent_sleeper(int this_cpu, runqueue_t *this_rq)
{
struct sched_domain *sd = this_rq->sd;
struct sched_domain *tmp, *sd = NULL;
cpumask_t sibling_map;
prio_array_t *array;
int ret = 0, i;
task_t *p;
if (!(sd->flags & SD_SHARE_CPUPOWER))
for_each_domain(this_cpu, tmp)
if (tmp->flags & SD_SHARE_CPUPOWER)
sd = tmp;
if (!sd)
return 0;
/*
@ -4617,6 +4625,11 @@ static void sched_domain_debug(struct sched_domain *sd, int cpu)
{
int level = 0;
if (!sd) {
printk(KERN_DEBUG "CPU%d attaching NULL sched-domain.\n", cpu);
return;
}
printk(KERN_DEBUG "CPU%d attaching sched-domain:\n", cpu);
do {
@ -4874,7 +4887,7 @@ static void __devinit arch_init_sched_domains(void)
cpus_and(cpu_default_map, cpu_default_map, cpu_online_map);
/*
* Set up domains. Isolated domains just stay on the dummy domain.
* Set up domains. Isolated domains just stay on the NULL domain.
*/
for_each_cpu_mask(i, cpu_default_map) {
int group;
@ -4987,18 +5000,11 @@ static void __devinit arch_destroy_sched_domains(void)
#endif /* ARCH_HAS_SCHED_DOMAIN */
/*
* Initial dummy domain for early boot and for hotplug cpu. Being static,
* it is initialized to zero, so all balancing flags are cleared which is
* what we want.
*/
static struct sched_domain sched_domain_dummy;
#ifdef CONFIG_HOTPLUG_CPU
/*
* Force a reinitialization of the sched domains hierarchy. The domains
* and groups cannot be updated in place without racing with the balancing
* code, so we temporarily attach all running cpus to a "dummy" domain
* code, so we temporarily attach all running cpus to the NULL domain
* which will prevent rebalancing while the sched domains are recalculated.
*/
static int update_sched_domains(struct notifier_block *nfb,
@ -5010,7 +5016,7 @@ static int update_sched_domains(struct notifier_block *nfb,
case CPU_UP_PREPARE:
case CPU_DOWN_PREPARE:
for_each_online_cpu(i)
cpu_attach_domain(&sched_domain_dummy, i);
cpu_attach_domain(NULL, i);
arch_destroy_sched_domains();
return NOTIFY_OK;
@ -5072,7 +5078,7 @@ void __init sched_init(void)
rq->best_expired_prio = MAX_PRIO;
#ifdef CONFIG_SMP
rq->sd = &sched_domain_dummy;
rq->sd = NULL;
for (j = 1; j < 3; j++)
rq->cpu_load[j] = 0;
rq->active_balance = 0;