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sched: convert nohz_cpu_mask 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.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Rusty Russell 2008-11-25 02:35:04 +10:30 committed by Ingo Molnar
parent 6c99e9ad47
commit 6a7b3dc344
4 changed files with 12 additions and 9 deletions
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2
include/linux/sched.h
View file

@ -249,7 +249,7 @@ extern void init_idle_bootup_task(struct task_struct *idle);
extern int runqueue_is_locked(void);
extern void task_rq_unlock_wait(struct task_struct *p);
extern cpumask_t nohz_cpu_mask;
extern cpumask_var_t nohz_cpu_mask;
#if defined(CONFIG_SMP) && defined(CONFIG_NO_HZ)
extern int select_nohz_load_balancer(int cpu);
#else

2
kernel/rcuclassic.c
View file

@ -393,7 +393,7 @@ static void rcu_start_batch(struct rcu_ctrlblk *rcp)
* unnecessarily.
*/
smp_mb();
cpus_andnot(rcp->cpumask, cpu_online_map, nohz_cpu_mask);
cpumask_andnot(&rcp->cpumask, cpu_online_mask, nohz_cpu_mask);
rcp->signaled = 0;
}

7
kernel/sched.c
View file

@ -5870,9 +5870,9 @@ void __cpuinit init_idle(struct task_struct *idle, int cpu)
* indicates which cpus entered this state. This is used
* in the rcu update to wait only for active cpus. For system
* which do not switch off the HZ timer nohz_cpu_mask should
* always be CPU_MASK_NONE.
* always be CPU_BITS_NONE.
*/
cpumask_t nohz_cpu_mask = CPU_MASK_NONE;
cpumask_var_t nohz_cpu_mask;
/*
* Increase the granularity value when there are more CPUs,
@ -8274,6 +8274,9 @@ void __init sched_init(void)
*/
current->sched_class = &fair_sched_class;
/* Allocate the nohz_cpu_mask if CONFIG_CPUMASK_OFFSTACK */
alloc_bootmem_cpumask_var(&nohz_cpu_mask);
scheduler_running = 1;
}

10
kernel/time/tick-sched.c
View file

@ -144,7 +144,7 @@ void tick_nohz_update_jiffies(void)
if (!ts->tick_stopped)
return;
cpu_clear(cpu, nohz_cpu_mask);
cpumask_clear_cpu(cpu, nohz_cpu_mask);
now = ktime_get();
ts->idle_waketime = now;
@ -283,7 +283,7 @@ void tick_nohz_stop_sched_tick(int inidle)
if ((long)delta_jiffies >= 1) {
if (delta_jiffies > 1)
cpu_set(cpu, nohz_cpu_mask);
cpumask_set_cpu(cpu, nohz_cpu_mask);
/*
* nohz_stop_sched_tick can be called several times before
* the nohz_restart_sched_tick is called. This happens when
@ -296,7 +296,7 @@ void tick_nohz_stop_sched_tick(int inidle)
/*
* sched tick not stopped!
*/
cpu_clear(cpu, nohz_cpu_mask);
cpumask_clear_cpu(cpu, nohz_cpu_mask);
goto out;
}
@ -354,7 +354,7 @@ void tick_nohz_stop_sched_tick(int inidle)
* softirq.
*/
tick_do_update_jiffies64(ktime_get());
cpu_clear(cpu, nohz_cpu_mask);
cpumask_clear_cpu(cpu, nohz_cpu_mask);
}
raise_softirq_irqoff(TIMER_SOFTIRQ);
out:
@ -432,7 +432,7 @@ void tick_nohz_restart_sched_tick(void)
select_nohz_load_balancer(0);
now = ktime_get();
tick_do_update_jiffies64(now);
cpu_clear(cpu, nohz_cpu_mask);
cpumask_clear_cpu(cpu, nohz_cpu_mask);
/*
* We stopped the tick in idle. Update process times would miss the