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sched: convert struct root_domain to cpumask_var_t.
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Impact: (future) size reduction for large NR_CPUS.

Dynamically allocating cpumasks (when CONFIG_CPUMASK_OFFSTACK) saves
space for small nr_cpu_ids but big CONFIG_NR_CPUS.  cpumask_var_t
is just a struct cpumask for !CONFIG_CPUMASK_OFFSTACK.

def_root_domain is static, and so its masks are initialized with
alloc_bootmem_cpumask_var.  After that, alloc_cpumask_var is used.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Rusty Russell authored and Ingo Molnar committed Nov 24, 2008
1 parent 6a7b3dc commit c6c4927
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Showing 2 changed files with 64 additions and 31 deletions.
69 changes: 51 additions & 18 deletions kernel/sched.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -487,14 +487,14 @@ struct rt_rq {
*/
struct root_domain {
atomic_t refcount;
cpumask_t span;
cpumask_t online;
cpumask_var_t span;
cpumask_var_t online;

/*
* The "RT overload" flag: it gets set if a CPU has more than
* one runnable RT task.
*/
cpumask_t rto_mask;
cpumask_var_t rto_mask;
atomic_t rto_count;
#ifdef CONFIG_SMP
struct cpupri cpupri;
Expand Down Expand Up @@ -6444,7 +6444,7 @@ static void set_rq_online(struct rq *rq)
if (!rq->online) {
const struct sched_class *class;

cpu_set(rq->cpu, rq->rd->online);
cpumask_set_cpu(rq->cpu, rq->rd->online);
rq->online = 1;

for_each_class(class) {
Expand All @@ -6464,7 +6464,7 @@ static void set_rq_offline(struct rq *rq)
class->rq_offline(rq);
}

cpu_clear(rq->cpu, rq->rd->online);
cpumask_clear_cpu(rq->cpu, rq->rd->online);
rq->online = 0;
}
}
Expand Down Expand Up @@ -6505,7 +6505,7 @@ migration_call(struct notifier_block *nfb, unsigned long action, void *hcpu)
rq = cpu_rq(cpu);
spin_lock_irqsave(&rq->lock, flags);
if (rq->rd) {
BUG_ON(!cpu_isset(cpu, rq->rd->span));
BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span));

set_rq_online(rq);
}
Expand Down Expand Up @@ -6567,7 +6567,7 @@ migration_call(struct notifier_block *nfb, unsigned long action, void *hcpu)
rq = cpu_rq(cpu);
spin_lock_irqsave(&rq->lock, flags);
if (rq->rd) {
BUG_ON(!cpu_isset(cpu, rq->rd->span));
BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span));
set_rq_offline(rq);
}
spin_unlock_irqrestore(&rq->lock, flags);
Expand Down Expand Up @@ -6768,6 +6768,14 @@ sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent)
return 1;
}

static void free_rootdomain(struct root_domain *rd)
{
free_cpumask_var(rd->rto_mask);
free_cpumask_var(rd->online);
free_cpumask_var(rd->span);
kfree(rd);
}

static void rq_attach_root(struct rq *rq, struct root_domain *rd)
{
unsigned long flags;
Expand All @@ -6777,38 +6785,60 @@ static void rq_attach_root(struct rq *rq, struct root_domain *rd)
if (rq->rd) {
struct root_domain *old_rd = rq->rd;

if (cpu_isset(rq->cpu, old_rd->online))
if (cpumask_test_cpu(rq->cpu, old_rd->online))
set_rq_offline(rq);

cpu_clear(rq->cpu, old_rd->span);
cpumask_clear_cpu(rq->cpu, old_rd->span);

if (atomic_dec_and_test(&old_rd->refcount))
kfree(old_rd);
free_rootdomain(old_rd);
}

atomic_inc(&rd->refcount);
rq->rd = rd;

cpu_set(rq->cpu, rd->span);
if (cpu_isset(rq->cpu, cpu_online_map))
cpumask_set_cpu(rq->cpu, rd->span);
if (cpumask_test_cpu(rq->cpu, cpu_online_mask))
set_rq_online(rq);

spin_unlock_irqrestore(&rq->lock, flags);
}

static void init_rootdomain(struct root_domain *rd)
static int init_rootdomain(struct root_domain *rd, bool bootmem)
{
memset(rd, 0, sizeof(*rd));

cpus_clear(rd->span);
cpus_clear(rd->online);
if (bootmem) {
alloc_bootmem_cpumask_var(&def_root_domain.span);
alloc_bootmem_cpumask_var(&def_root_domain.online);
alloc_bootmem_cpumask_var(&def_root_domain.rto_mask);
cpupri_init(&rd->cpupri);
return 0;
}

if (!alloc_cpumask_var(&rd->span, GFP_KERNEL))
goto free_rd;
if (!alloc_cpumask_var(&rd->online, GFP_KERNEL))
goto free_span;
if (!alloc_cpumask_var(&rd->rto_mask, GFP_KERNEL))
goto free_online;

cpupri_init(&rd->cpupri);
return 0;

free_online:
free_cpumask_var(rd->online);
free_span:
free_cpumask_var(rd->span);
free_rd:
kfree(rd);
return -ENOMEM;
}

static void init_defrootdomain(void)
{
init_rootdomain(&def_root_domain);
init_rootdomain(&def_root_domain, true);

atomic_set(&def_root_domain.refcount, 1);
}

Expand All @@ -6820,7 +6850,10 @@ static struct root_domain *alloc_rootdomain(void)
if (!rd)
return NULL;

init_rootdomain(rd);
if (init_rootdomain(rd, false) != 0) {
kfree(rd);
return NULL;
}

return rd;
}
Expand Down Expand Up @@ -7632,7 +7665,7 @@ static int __build_sched_domains(const cpumask_t *cpu_map,
#ifdef CONFIG_NUMA
error:
free_sched_groups(cpu_map, tmpmask);
kfree(rd);
free_rootdomain(rd);
goto free_tmpmask;
#endif
}
Expand Down
26 changes: 13 additions & 13 deletions kernel/sched_rt.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -15,7 +15,7 @@ static inline void rt_set_overload(struct rq *rq)
if (!rq->online)
return;

cpu_set(rq->cpu, rq->rd->rto_mask);
cpumask_set_cpu(rq->cpu, rq->rd->rto_mask);
/*
* Make sure the mask is visible before we set
* the overload count. That is checked to determine
Expand All @@ -34,7 +34,7 @@ static inline void rt_clear_overload(struct rq *rq)

/* the order here really doesn't matter */
atomic_dec(&rq->rd->rto_count);
cpu_clear(rq->cpu, rq->rd->rto_mask);
cpumask_clear_cpu(rq->cpu, rq->rd->rto_mask);
}

static void update_rt_migration(struct rq *rq)
Expand Down Expand Up @@ -139,14 +139,14 @@ static int rt_se_boosted(struct sched_rt_entity *rt_se)
}

#ifdef CONFIG_SMP
static inline cpumask_t sched_rt_period_mask(void)
static inline const struct cpumask *sched_rt_period_mask(void)
{
return cpu_rq(smp_processor_id())->rd->span;
}
#else
static inline cpumask_t sched_rt_period_mask(void)
static inline const struct cpumask *sched_rt_period_mask(void)
{
return cpu_online_map;
return cpu_online_mask;
}
#endif

Expand Down Expand Up @@ -212,9 +212,9 @@ static inline int rt_rq_throttled(struct rt_rq *rt_rq)
return rt_rq->rt_throttled;
}

static inline cpumask_t sched_rt_period_mask(void)
static inline const struct cpumask *sched_rt_period_mask(void)
{
return cpu_online_map;
return cpu_online_mask;
}

static inline
Expand All @@ -241,11 +241,11 @@ static int do_balance_runtime(struct rt_rq *rt_rq)
int i, weight, more = 0;
u64 rt_period;

weight = cpus_weight(rd->span);
weight = cpumask_weight(rd->span);

spin_lock(&rt_b->rt_runtime_lock);
rt_period = ktime_to_ns(rt_b->rt_period);
for_each_cpu_mask_nr(i, rd->span) {
for_each_cpu(i, rd->span) {
struct rt_rq *iter = sched_rt_period_rt_rq(rt_b, i);
s64 diff;

Expand Down Expand Up @@ -324,7 +324,7 @@ static void __disable_runtime(struct rq *rq)
/*
* Greedy reclaim, take back as much as we can.
*/
for_each_cpu_mask(i, rd->span) {
for_each_cpu(i, rd->span) {
struct rt_rq *iter = sched_rt_period_rt_rq(rt_b, i);
s64 diff;

Expand Down Expand Up @@ -429,13 +429,13 @@ static inline int balance_runtime(struct rt_rq *rt_rq)
static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun)
{
int i, idle = 1;
cpumask_t span;
const struct cpumask *span;

if (!rt_bandwidth_enabled() || rt_b->rt_runtime == RUNTIME_INF)
return 1;

span = sched_rt_period_mask();
for_each_cpu_mask(i, span) {
for_each_cpu(i, span) {
int enqueue = 0;
struct rt_rq *rt_rq = sched_rt_period_rt_rq(rt_b, i);
struct rq *rq = rq_of_rt_rq(rt_rq);
Expand Down Expand Up @@ -1181,7 +1181,7 @@ static int pull_rt_task(struct rq *this_rq)

next = pick_next_task_rt(this_rq);

for_each_cpu_mask_nr(cpu, this_rq->rd->rto_mask) {
for_each_cpu(cpu, this_rq->rd->rto_mask) {
if (this_cpu == cpu)
continue;

Expand Down

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