C++ set_cpus_allowed函数代码示例

void cpu_idle_wait(void)
{
    unsigned int cpu, this_cpu = get_cpu();
    cpumask_t map, tmp = current->cpus_allowed;

    set_cpus_allowed(current, cpumask_of_cpu(this_cpu));
    put_cpu();

    cpus_clear(map);
    for_each_online_cpu(cpu) {
        per_cpu(cpu_idle_state, cpu) = 1;
        cpu_set(cpu, map);
    }

    __get_cpu_var(cpu_idle_state) = 0;

    wmb();
    do {
        ssleep(1);
        for_each_online_cpu(cpu) {
            if (cpu_isset(cpu, map) && !per_cpu(cpu_idle_state, cpu))
                cpu_clear(cpu, map);
        }
        cpus_and(map, map, cpu_online_map);
    } while (!cpus_empty(map));

    set_cpus_allowed(current, tmp);
}

static void
call_on_cpu(int cpu, void (*fn)(void *), void *arg)
{
	cpumask_t save_cpus_allowed = current->cpus_allowed;
	cpumask_t new_cpus_allowed = cpumask_of_cpu(cpu);
	set_cpus_allowed(current, new_cpus_allowed);
	(*fn)(arg);
	set_cpus_allowed(current, save_cpus_allowed);
}

static void
call_on_cpu(int cpu, void (*fn)(void *), void *arg)
{
	cpumask_t save_cpus_allowed, new_cpus_allowed;
	memcpy(&save_cpus_allowed, &current->cpus_allowed, sizeof(save_cpus_allowed));
	memset(&new_cpus_allowed, 0, sizeof(new_cpus_allowed));
	set_bit(cpu, &new_cpus_allowed);
	set_cpus_allowed(current, new_cpus_allowed);
	(*fn)(arg);
	set_cpus_allowed(current, save_cpus_allowed);
}

void linsched_enable_migrations(void)
{
	int i;

	for (i = 0; i < curr_task_id; i++)
		set_cpus_allowed(__linsched_tasks[i], CPU_MASK_ALL);
}

/*
 * The CPUFREQ_ADJUST notifier is used to override the current policy min to
 * make sure policy min >= boost_min. The cpufreq framework then does the job
 * of enforcing the new policy.
 *
 * The sync kthread needs to run on the CPU in question to avoid deadlocks in
 * the wake up code. Achieve this by binding the thread to the respective
 * CPU. But a CPU going offline unbinds threads from that CPU. So, set it up
 * again each time the CPU comes back up. We can use CPUFREQ_START to figure
 * out a CPU is coming online instead of registering for hotplug notifiers.
 */
static int boost_adjust_notify(struct notifier_block *nb, unsigned long val, void *data)
{
	struct cpufreq_policy *policy = data;
	unsigned int cpu = policy->cpu;
	struct cpu_sync *s = &per_cpu(sync_info, cpu);
	unsigned int b_min = s->boost_min;
	unsigned int ib_min = s->input_boost_min;
	unsigned int min;

	switch (val) {
	case CPUFREQ_ADJUST:
		if (!b_min && !ib_min)
			break;

		min = max(b_min, ib_min);

		pr_debug("CPU%u policy min before boost: %u kHz\n",
			 cpu, policy->min);
		pr_debug("CPU%u boost min: %u kHz\n", cpu, min);

		cpufreq_verify_within_limits(policy, min, UINT_MAX);

		pr_debug("CPU%u policy min after boost: %u kHz\n",
			 cpu, policy->min);
		break;

	case CPUFREQ_START:
		set_cpus_allowed(s->thread, *cpumask_of(cpu));
		break;
	}

	return NOTIFY_OK;
}

static void mpc85xx_smp_machine_kexec(struct kimage *image)
{
	int timeout = 2000;
	int i;

	set_cpus_allowed(current, cpumask_of_cpu(boot_cpuid));

	smp_call_function(mpc85xx_smp_kexec_down, NULL, 0);

	while ( (kexec_down_cpus != (num_online_cpus() - 1)) &&
		( timeout > 0 ) )
	{
		timeout--;
	}

	if ( !timeout )
		printk(KERN_ERR "Unable to bring down secondary cpu(s)");

	for (i = 0; i < num_present_cpus(); i++)
	{
		if ( i == smp_processor_id() ) continue;
		mpic_reset_core(i);
	}

	default_machine_kexec(image);
}

/*
 * Boost hierarchy: there are three kinds of boosts, and some
 * boosts will take precedence over others. Below is the current
 * hierarchy, from most precedence to least precedence:
 *
 * 1. Framebuffer blank/unblank boost
 * 2. Thread-migration boost (only if the mig boost freq > policy->min)
 * 3. Input boost
 */
static int cpu_do_boost(struct notifier_block *nb, unsigned long val, void *data)
{
	struct cpufreq_policy *policy = data;
	struct boost_policy *b = &per_cpu(boost_info, policy->cpu);

	if (val == CPUFREQ_START) {
		set_cpus_allowed(b->thread, *cpumask_of(b->cpu));
		return NOTIFY_OK;
	}

	if (val != CPUFREQ_ADJUST)
		return NOTIFY_OK;

	switch (b->boost_state) {
	case UNBOOST:
		policy->min = policy->cpuinfo.min_freq;
		break;
	case BOOST:
		policy->min = min(policy->max, ib_freq[policy->cpu]);
		break;
	}

	if (b->migration_freq > policy->min)
		policy->min = min(policy->max, b->migration_freq);

	if (fb_boost)
		policy->min = policy->max;

	return NOTIFY_OK;
}

static int integrator_set_target(struct cpufreq_policy *policy,
				 unsigned int target_freq,
				 unsigned int relation)
{
	cpumask_t cpus_allowed;
	int cpu = policy->cpu;
	struct icst525_vco vco;
	struct cpufreq_freqs freqs;
	u_int cm_osc;

	/*
	 * Save this threads cpus_allowed mask.
	 */
	cpus_allowed = current->cpus_allowed;

	/*
	 * Bind to the specified CPU.  When this call returns,
	 * we should be running on the right CPU.
	 */
	set_cpus_allowed(current, cpumask_of_cpu(cpu));
	BUG_ON(cpu != smp_processor_id());

	/* get current setting */
	cm_osc = __raw_readl(CM_OSC);

	if (machine_is_integrator()) {
		vco.s = (cm_osc >> 8) & 7;
	} else if (machine_is_cintegrator()) {

static int cpu_boost_init(void)
{
	int cpu, ret;
	struct cpu_sync *s;

	cpu_boost_wq = alloc_workqueue("cpuboost_wq", WQ_HIGHPRI, 0);
	if (!cpu_boost_wq)
		return -EFAULT;

	INIT_WORK(&input_boost_work, do_input_boost);

	for_each_possible_cpu(cpu) {
		s = &per_cpu(sync_info, cpu);
		s->cpu = cpu;
		init_waitqueue_head(&s->sync_wq);
		atomic_set(&s->being_woken, 0);
		spin_lock_init(&s->lock);
		INIT_DELAYED_WORK(&s->boost_rem, do_boost_rem);
		INIT_DELAYED_WORK(&s->input_boost_rem, do_input_boost_rem);
		s->thread = kthread_run(boost_mig_sync_thread, (void *)cpu,
					"boost_sync/%d", cpu);
		set_cpus_allowed(s->thread, *cpumask_of(cpu));
	}
	cpufreq_register_notifier(&boost_adjust_nb, CPUFREQ_POLICY_NOTIFIER);
	atomic_notifier_chain_register(&migration_notifier_head,
					&boost_migration_nb);
	ret = input_register_handler(&cpuboost_input_handler);

	return 0;
}

static int hello_init(void)
{
	printk(KERN_ALERT "Ready to start kthread.\n");
	gpkthmykth[0] = kthread_create(mykthread_t, NULL, gacMyktname);
	gpkthmykth[1] = kthread_create(mykthread,   NULL, gacMyktname);
	gpkthmykth[2] = kthread_create(mykthread,   NULL, gacMyktname);
	gpkthmykth[3] = kthread_create(mykthread,   NULL, gacMyktname);
	set_cpus_allowed(gpkthmykth[0], *cpumask_of(0));
	set_cpus_allowed(gpkthmykth[1], *cpumask_of(1));
	set_cpus_allowed(gpkthmykth[2], *cpumask_of(2));
	set_cpus_allowed(gpkthmykth[3], *cpumask_of(3));
	wake_up_process(gpkthmykth[0]);
	wake_up_process(gpkthmykth[1]);
	wake_up_process(gpkthmykth[2]);
	wake_up_process(gpkthmykth[3]);
	return 0;
}

/* XXX convert to rusty's on_one_cpu */
static unsigned long run_on_cpu(unsigned long cpu,
			        unsigned long (*func)(unsigned long),
				unsigned long arg)
{
	cpumask_t old_affinity = current->cpus_allowed;
	unsigned long ret;

	/* should return -EINVAL to userspace */
	if (set_cpus_allowed(current, cpumask_of_cpu(cpu)))
		return 0;

	ret = func(arg);

	set_cpus_allowed(current, old_affinity);

	return ret;
}

static int __init kernel_init(void * unused)
{
#ifndef __LINSCHED__
	lock_kernel();
	/*
	 * init can run on any cpu.
	 */
	set_cpus_allowed(current, CPU_MASK_ALL);
	/*
	 * Tell the world that we're going to be the grim
	 * reaper of innocent orphaned children.
	 *
	 * We don't want people to have to make incorrect
	 * assumptions about where in the task array this
	 * can be found.
	 */
	init_pid_ns.child_reaper = current;

	__set_special_pids(1, 1);
	cad_pid = task_pid(current);

	smp_prepare_cpus(max_cpus);

	do_pre_smp_initcalls();

	smp_init();
#endif /* __LINSCHED__ */

	sched_init_smp();

#ifndef __LINSCHED__
	cpuset_init_smp();

	do_basic_setup();

	/*
	 * check if there is an early userspace init.  If yes, let it do all
	 * the work
	 */

	if (!ramdisk_execute_command)
		ramdisk_execute_command = "/init";

	if (sys_access((const char __user *) ramdisk_execute_command, 0) != 0) {
		ramdisk_execute_command = NULL;
		prepare_namespace();
	}

	/*
	 * Ok, we have completed the initial bootup, and
	 * we're essentially up and running. Get rid of the
	 * initmem segments and start the user-mode stuff..
	 */
	init_post();
#endif /* __LINSCHED__ */

	return 0;
}

void linsched_disable_migrations(void)
{
	int i;

	for (i = 0; i < curr_task_id; i++)
		set_cpus_allowed(__linsched_tasks[i],
				 cpumask_of_cpu(
					 task_cpu(__linsched_tasks[i])));
}

struct task_struct *__linsched_create_task_binary(void (*callback)(void), unsigned long time_slice)
{
        struct task_struct *newtask =
                (struct task_struct *)do_fork_binary(0, 0, 0, 0, 0, 0, callback, time_slice);

        set_cpus_allowed(newtask, CPU_MASK_ALL);

        return newtask;
}

static void
acpi_power_off (void)
{
	printk("%s called\n",__FUNCTION__);
	/* Some SMP machines only can poweroff in boot CPU */
	set_cpus_allowed(current, cpumask_of_cpu(0));
	acpi_enter_sleep_state_prep(ACPI_STATE_S5);
	ACPI_DISABLE_IRQS();
	acpi_enter_sleep_state(ACPI_STATE_S5);
}