[PATCH] sched: null domains
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>
diff --git a/kernel/sched.c b/kernel/sched.c
index b141057..77c07c2 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -2579,11 +2579,15 @@
#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 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 @@
{
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 @@
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 @@
#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 @@
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 @@
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;