Commit 1cb6bb4b authored by Heiko Carstens's avatar Heiko Carstens Committed by Martin Schwidefsky
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[S390] Allocate and free cpu lowcores and stacks when needed/possible. 



No need to preallocate the per cpu lowcores and stacks.
Savings are 28-32k per offline cpu.

Signed-off-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent c11ca97e

arch/s390/kernel/smp.c

+72 −34
Original line number Diff line number Diff line
@@ -589,8 +589,72 @@ static void __init smp_create_idle(unsigned int cpu) 
	spin_lock_init(&(&per_cpu(s390_idle, cpu))->lock);

}



static int __cpuinit smp_alloc_lowcore(int cpu)

{

	unsigned long async_stack, panic_stack;

	struct _lowcore *lowcore;

	int lc_order;



	lc_order = sizeof(long) == 8 ? 1 : 0;

	lowcore = (void *) __get_free_pages(GFP_KERNEL | GFP_DMA, lc_order);

	if (!lowcore)

		return -ENOMEM;

	async_stack = __get_free_pages(GFP_KERNEL, ASYNC_ORDER);

	if (!async_stack)

		goto out_async_stack;

	panic_stack = __get_free_page(GFP_KERNEL);

	if (!panic_stack)

		goto out_panic_stack;



	*lowcore = S390_lowcore;

	lowcore->async_stack = async_stack + ASYNC_SIZE;

	lowcore->panic_stack = panic_stack + PAGE_SIZE;



#ifndef CONFIG_64BIT

	if (MACHINE_HAS_IEEE) {

		unsigned long save_area;



		save_area = get_zeroed_page(GFP_KERNEL);

		if (!save_area)

			goto out_save_area;

		lowcore->extended_save_area_addr = (u32) save_area;

	}

#endif

	lowcore_ptr[cpu] = lowcore;

	return 0;



#ifndef CONFIG_64BIT

out_save_area:

	free_page(panic_stack);

#endif

out_panic_stack:

	free_pages(async_stack, ASYNC_ORDER);

out_async_stack:

	free_pages((unsigned long) lowcore, lc_order);

	return -ENOMEM;

}



#ifdef CONFIG_HOTPLUG_CPU

static void smp_free_lowcore(int cpu)

{

	struct _lowcore *lowcore;

	int lc_order;



	lc_order = sizeof(long) == 8 ? 1 : 0;

	lowcore = lowcore_ptr[cpu];

#ifndef CONFIG_64BIT

	if (MACHINE_HAS_IEEE)

		free_page((unsigned long) lowcore->extended_save_area_addr);

#endif

	free_page(lowcore->panic_stack - PAGE_SIZE);

	free_pages(lowcore->async_stack - ASYNC_SIZE, ASYNC_ORDER);

	free_pages((unsigned long) lowcore, lc_order);

	lowcore_ptr[cpu] = NULL;

}

#endif /* CONFIG_HOTPLUG_CPU */



/* Upping and downing of CPUs */

int __cpu_up(unsigned int cpu)

int __cpuinit __cpu_up(unsigned int cpu)

{

	struct task_struct *idle;

	struct _lowcore *cpu_lowcore;
@@ -599,6 +663,8 @@ int __cpu_up(unsigned int cpu) 


	if (smp_cpu_state[cpu] != CPU_STATE_CONFIGURED)

		return -EIO;

	if (smp_alloc_lowcore(cpu))

		return -ENOMEM;



	ccode = signal_processor_p((__u32)(unsigned long)(lowcore_ptr[cpu]),

				   cpu, sigp_set_prefix);
@@ -613,6 +679,7 @@ int __cpu_up(unsigned int cpu) 
	cpu_lowcore = lowcore_ptr[cpu];

	cpu_lowcore->kernel_stack = (unsigned long)

		task_stack_page(idle) + THREAD_SIZE;

	cpu_lowcore->thread_info = (unsigned long) task_thread_info(idle);

	sf = (struct stack_frame *) (cpu_lowcore->kernel_stack

				     - sizeof(struct pt_regs)

				     - sizeof(struct stack_frame));
@@ -626,6 +693,8 @@ int __cpu_up(unsigned int cpu) 
	cpu_lowcore->percpu_offset = __per_cpu_offset[cpu];

	cpu_lowcore->current_task = (unsigned long) idle;

	cpu_lowcore->cpu_data.cpu_nr = cpu;

	cpu_lowcore->softirq_pending = 0;

	cpu_lowcore->ext_call_fast = 0;

	eieio();



	while (signal_processor(cpu, sigp_restart) == sigp_busy)
@@ -686,6 +755,7 @@ void __cpu_die(unsigned int cpu) 
	/* Wait until target cpu is down */

	while (!smp_cpu_not_running(cpu))

		cpu_relax();

	smp_free_lowcore(cpu);

	printk(KERN_INFO "Processor %d spun down\n", cpu);

}
@@ -699,15 +769,9 @@ void cpu_die(void) 


#endif /* CONFIG_HOTPLUG_CPU */



/*

 *	Cycle through the processors and setup structures.

 */



void __init smp_prepare_cpus(unsigned int max_cpus)

{

	unsigned long stack;

	unsigned int cpu;

	int i;



	smp_detect_cpus();
@@ -715,35 +779,9 @@ void __init smp_prepare_cpus(unsigned int max_cpus) 
	if (register_external_interrupt(0x1201, do_ext_call_interrupt) != 0)

		panic("Couldn't request external interrupt 0x1201");

	memset(lowcore_ptr, 0, sizeof(lowcore_ptr));

	/*

	 *  Initialize prefix pages and stacks for all possible cpus

	 */

	print_cpu_info(&S390_lowcore.cpu_data);

	smp_alloc_lowcore(smp_processor_id());



	for_each_possible_cpu(i) {

		lowcore_ptr[i] = (struct _lowcore *)

			__get_free_pages(GFP_KERNEL | GFP_DMA,

					 sizeof(void*) == 8 ? 1 : 0);

		stack = __get_free_pages(GFP_KERNEL, ASYNC_ORDER);

		if (!lowcore_ptr[i] || !stack)

			panic("smp_boot_cpus failed to allocate memory\n");



		*(lowcore_ptr[i]) = S390_lowcore;

		lowcore_ptr[i]->async_stack = stack + ASYNC_SIZE;

		stack = __get_free_pages(GFP_KERNEL, 0);

		if (!stack)

			panic("smp_boot_cpus failed to allocate memory\n");

		lowcore_ptr[i]->panic_stack = stack + PAGE_SIZE;

#ifndef CONFIG_64BIT

		if (MACHINE_HAS_IEEE) {

			lowcore_ptr[i]->extended_save_area_addr =

				(__u32) __get_free_pages(GFP_KERNEL, 0);

			if (!lowcore_ptr[i]->extended_save_area_addr)

				panic("smp_boot_cpus failed to "

				      "allocate memory\n");

		}

#endif

	}

#ifndef CONFIG_64BIT

	if (MACHINE_HAS_IEEE)

		ctl_set_bit(14, 29); /* enable extended save area */