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Commit a4a6198b authored by Jan Beulich's avatar Jan Beulich Committed by Linus Torvalds
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[PATCH] tvec_bases too large for per-cpu data 



With internal Xen-enabled kernels we see the kernel's static per-cpu data
area exceed the limit of 32k on x86-64, and even native x86-64 kernels get
fairly close to that limit.  I generally question whether it is reasonable
to have data structures several kb in size allocated as per-cpu data when
the space there is rather limited.

The biggest arch-independent consumer is tvec_bases (over 4k on 32-bit
archs, over 8k on 64-bit ones), which now gets converted to use dynamically
allocated memory instead.

Signed-off-by: default avatarJan Beulich <jbeulich@novell.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent c98d8cfb

kernel/timer.c

+34 −11
Original line number Diff line number Diff line
@@ -86,7 +86,8 @@ struct tvec_t_base_s { 
} ____cacheline_aligned_in_smp;



typedef struct tvec_t_base_s tvec_base_t;

static DEFINE_PER_CPU(tvec_base_t, tvec_bases);

static DEFINE_PER_CPU(tvec_base_t *, tvec_bases);

static tvec_base_t boot_tvec_bases;



static inline void set_running_timer(tvec_base_t *base,

					struct timer_list *timer)
@@ -157,7 +158,7 @@ EXPORT_SYMBOL(__init_timer_base); 
void fastcall init_timer(struct timer_list *timer)

{

	timer->entry.next = NULL;

	timer->base = &per_cpu(tvec_bases, raw_smp_processor_id()).t_base;

	timer->base = &per_cpu(tvec_bases, raw_smp_processor_id())->t_base;

}

EXPORT_SYMBOL(init_timer);
@@ -218,7 +219,7 @@ int __mod_timer(struct timer_list *timer, unsigned long expires) 
		ret = 1;

	}



	new_base = &__get_cpu_var(tvec_bases);

	new_base = __get_cpu_var(tvec_bases);



	if (base != &new_base->t_base) {

		/*
@@ -258,7 +259,7 @@ EXPORT_SYMBOL(__mod_timer); 
 */

void add_timer_on(struct timer_list *timer, int cpu)

{

	tvec_base_t *base = &per_cpu(tvec_bases, cpu);

	tvec_base_t *base = per_cpu(tvec_bases, cpu);

  	unsigned long flags;



  	BUG_ON(timer_pending(timer) || !timer->function);
@@ -504,7 +505,7 @@ unsigned long next_timer_interrupt(void) 
	}

	hr_expires += jiffies;



	base = &__get_cpu_var(tvec_bases);

	base = __get_cpu_var(tvec_bases);

	spin_lock(&base->t_base.lock);

	expires = base->timer_jiffies + (LONG_MAX >> 1);

	list = NULL;
@@ -901,7 +902,7 @@ EXPORT_SYMBOL(xtime_lock); 
 */

static void run_timer_softirq(struct softirq_action *h)

{

	tvec_base_t *base = &__get_cpu_var(tvec_bases);

	tvec_base_t *base = __get_cpu_var(tvec_bases);



 	hrtimer_run_queues();

	if (time_after_eq(jiffies, base->timer_jiffies))
@@ -1256,12 +1257,32 @@ asmlinkage long sys_sysinfo(struct sysinfo __user *info) 
	return 0;

}



static void __devinit init_timers_cpu(int cpu)

static int __devinit init_timers_cpu(int cpu)

{

	int j;

	tvec_base_t *base;



	base = &per_cpu(tvec_bases, cpu);

	base = per_cpu(tvec_bases, cpu);

	if (!base) {

		static char boot_done;



		/*

		 * Cannot do allocation in init_timers as that runs before the

		 * allocator initializes (and would waste memory if there are

		 * more possible CPUs than will ever be installed/brought up).

		 */

		if (boot_done) {

			base = kmalloc_node(sizeof(*base), GFP_KERNEL,

						cpu_to_node(cpu));

			if (!base)

				return -ENOMEM;

			memset(base, 0, sizeof(*base));

		} else {

			base = &boot_tvec_bases;

			boot_done = 1;

		}

		per_cpu(tvec_bases, cpu) = base;

	}

	spin_lock_init(&base->t_base.lock);

	for (j = 0; j < TVN_SIZE; j++) {

		INIT_LIST_HEAD(base->tv5.vec + j);
@@ -1273,6 +1294,7 @@ static void __devinit init_timers_cpu(int cpu) 
		INIT_LIST_HEAD(base->tv1.vec + j);



	base->timer_jiffies = jiffies;

	return 0;

}



#ifdef CONFIG_HOTPLUG_CPU
@@ -1295,8 +1317,8 @@ static void __devinit migrate_timers(int cpu) 
	int i;



	BUG_ON(cpu_online(cpu));

	old_base = &per_cpu(tvec_bases, cpu);

	new_base = &get_cpu_var(tvec_bases);

	old_base = per_cpu(tvec_bases, cpu);

	new_base = get_cpu_var(tvec_bases);



	local_irq_disable();

	spin_lock(&new_base->t_base.lock);
@@ -1326,7 +1348,8 @@ static int __devinit timer_cpu_notify(struct notifier_block *self, 
	long cpu = (long)hcpu;

	switch(action) {

	case CPU_UP_PREPARE:

		init_timers_cpu(cpu);

		if (init_timers_cpu(cpu) < 0)

			return NOTIFY_BAD;

		break;

#ifdef CONFIG_HOTPLUG_CPU

	case CPU_DEAD: