sched: convert struct sched_group/sched_domain cpumask_ts to variable bitmaps
Impact: (future) size reduction for large NR_CPUS.
We move the 'cpumask' member of sched_group to the end, so when we
kmalloc it we can do a minimal allocation: saves space for small
nr_cpu_ids but big CONFIG_NR_CPUS. Similar trick for 'span' in
sched_domain.
This isn't quite as good as converting to a cpumask_var_t, as some
sched_groups are actually static, but it's safer: we don't have to
figure out where to call alloc_cpumask_var/free_cpumask_var.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 2b95aa9..c5be6c6 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -771,7 +771,6 @@
struct sched_group {
struct sched_group *next; /* Must be a circular list */
- cpumask_t cpumask;
/*
* CPU power of this group, SCHED_LOAD_SCALE being max power for a
@@ -784,11 +783,13 @@
* (see include/linux/reciprocal_div.h)
*/
u32 reciprocal_cpu_power;
+
+ unsigned long cpumask[];
};
static inline struct cpumask *sched_group_cpus(struct sched_group *sg)
{
- return &sg->cpumask;
+ return to_cpumask(sg->cpumask);
}
enum sched_domain_level {
@@ -814,7 +815,6 @@
struct sched_domain *parent; /* top domain must be null terminated */
struct sched_domain *child; /* bottom domain must be null terminated */
struct sched_group *groups; /* the balancing groups of the domain */
- cpumask_t span; /* span of all CPUs in this domain */
unsigned long min_interval; /* Minimum balance interval ms */
unsigned long max_interval; /* Maximum balance interval ms */
unsigned int busy_factor; /* less balancing by factor if busy */
@@ -869,11 +869,14 @@
#ifdef CONFIG_SCHED_DEBUG
char *name;
#endif
+
+ /* span of all CPUs in this domain */
+ unsigned long span[];
};
static inline struct cpumask *sched_domain_span(struct sched_domain *sd)
{
- return &sd->span;
+ return to_cpumask(sd->span);
}
extern void partition_sched_domains(int ndoms_new, cpumask_t *doms_new,