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Commit 2f859d0d authored by Heiko Carstens's avatar Heiko Carstens Committed by Martin Schwidefsky
Browse files

s390/smp: reduce size of struct pcpu 



Reduce the size of struct pcpu, since the pcpu_devices array consists
of NR_CPUS elements of type struct pcpu. For most machines this is just
a waste of memory.
So let's try to make it a bit smaller.
This saves 16k with performance_defconfig.

Signed-off-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent da0c636e

arch/s390/kernel/smp.c

+27 −27
Original line number Diff line number Diff line
@@ -59,14 +59,13 @@ enum { 
	CPU_STATE_CONFIGURED,

};



static DEFINE_PER_CPU(struct cpu *, cpu_device);



struct pcpu {

	struct cpu *cpu;

	struct _lowcore *lowcore;	/* lowcore page(s) for the cpu */

	unsigned long async_stack;	/* async stack for the cpu */

	unsigned long panic_stack;	/* panic stack for the cpu */

	unsigned long ec_mask;		/* bit mask for ec_xxx functions */

	int state;			/* physical cpu state */

	int polarization;		/* physical polarization */

	signed char state;		/* physical cpu state */

	signed char polarization;	/* physical polarization */

	u16 address;			/* physical cpu address */

};
@@ -173,25 +172,30 @@ static void pcpu_ec_call(struct pcpu *pcpu, int ec_bit) 
	pcpu_sigp_retry(pcpu, order, 0);

}



#define ASYNC_FRAME_OFFSET (ASYNC_SIZE - STACK_FRAME_OVERHEAD - __PT_SIZE)

#define PANIC_FRAME_OFFSET (PAGE_SIZE - STACK_FRAME_OVERHEAD - __PT_SIZE)



static int pcpu_alloc_lowcore(struct pcpu *pcpu, int cpu)

{

	unsigned long async_stack, panic_stack;

	struct _lowcore *lc;



	if (pcpu != &pcpu_devices[0]) {

		pcpu->lowcore =	(struct _lowcore *)

			__get_free_pages(GFP_KERNEL | GFP_DMA, LC_ORDER);

		pcpu->async_stack = __get_free_pages(GFP_KERNEL, ASYNC_ORDER);

		pcpu->panic_stack = __get_free_page(GFP_KERNEL);

		if (!pcpu->lowcore || !pcpu->panic_stack || !pcpu->async_stack)

		async_stack = __get_free_pages(GFP_KERNEL, ASYNC_ORDER);

		panic_stack = __get_free_page(GFP_KERNEL);

		if (!pcpu->lowcore || !panic_stack || !async_stack)

			goto out;

	} else {

		async_stack = pcpu->lowcore->async_stack - ASYNC_FRAME_OFFSET;

		panic_stack = pcpu->lowcore->panic_stack - PANIC_FRAME_OFFSET;

	}

	lc = pcpu->lowcore;

	memcpy(lc, &S390_lowcore, 512);

	memset((char *) lc + 512, 0, sizeof(*lc) - 512);

	lc->async_stack = pcpu->async_stack + ASYNC_SIZE

		- STACK_FRAME_OVERHEAD - sizeof(struct pt_regs);

	lc->panic_stack = pcpu->panic_stack + PAGE_SIZE

		- STACK_FRAME_OVERHEAD - sizeof(struct pt_regs);

	lc->async_stack = async_stack + ASYNC_FRAME_OFFSET;

	lc->panic_stack = panic_stack + PANIC_FRAME_OFFSET;

	lc->cpu_nr = cpu;

	lc->spinlock_lockval = arch_spin_lockval(cpu);

#ifndef CONFIG_64BIT
@@ -212,8 +216,8 @@ static int pcpu_alloc_lowcore(struct pcpu *pcpu, int cpu) 
	return 0;

out:

	if (pcpu != &pcpu_devices[0]) {

		free_page(pcpu->panic_stack);

		free_pages(pcpu->async_stack, ASYNC_ORDER);

		free_page(panic_stack);

		free_pages(async_stack, ASYNC_ORDER);

		free_pages((unsigned long) pcpu->lowcore, LC_ORDER);

	}

	return -ENOMEM;
@@ -235,12 +239,12 @@ static void pcpu_free_lowcore(struct pcpu *pcpu) 
#else

	vdso_free_per_cpu(pcpu->lowcore);

#endif

	if (pcpu != &pcpu_devices[0]) {

		free_page(pcpu->panic_stack);

		free_pages(pcpu->async_stack, ASYNC_ORDER);

	if (pcpu == &pcpu_devices[0])

		return;

	free_page(pcpu->lowcore->panic_stack-PANIC_FRAME_OFFSET);

	free_pages(pcpu->lowcore->async_stack-ASYNC_FRAME_OFFSET, ASYNC_ORDER);

	free_pages((unsigned long) pcpu->lowcore, LC_ORDER);

}

}



#endif /* CONFIG_HOTPLUG_CPU */
@@ -366,7 +370,8 @@ void smp_call_online_cpu(void (*func)(void *), void *data) 
void smp_call_ipl_cpu(void (*func)(void *), void *data)

{

	pcpu_delegate(&pcpu_devices[0], func, data,

		      pcpu_devices->panic_stack + PAGE_SIZE);

		      pcpu_devices->lowcore->panic_stack -

		      PANIC_FRAME_OFFSET + PAGE_SIZE);

}



int smp_find_processor_id(u16 address)
@@ -935,10 +940,6 @@ void __init smp_prepare_boot_cpu(void) 
	pcpu->state = CPU_STATE_CONFIGURED;

	pcpu->address = stap();

	pcpu->lowcore = (struct _lowcore *)(unsigned long) store_prefix();

	pcpu->async_stack = S390_lowcore.async_stack - ASYNC_SIZE

		+ STACK_FRAME_OVERHEAD + sizeof(struct pt_regs);

	pcpu->panic_stack = S390_lowcore.panic_stack - PAGE_SIZE

		+ STACK_FRAME_OVERHEAD + sizeof(struct pt_regs);

	S390_lowcore.percpu_offset = __per_cpu_offset[0];

	smp_cpu_set_polarization(0, POLARIZATION_UNKNOWN);

	set_cpu_present(0, true);
@@ -1078,8 +1079,7 @@ static int smp_cpu_notify(struct notifier_block *self, unsigned long action, 
			  void *hcpu)

{

	unsigned int cpu = (unsigned int)(long)hcpu;

	struct cpu *c = pcpu_devices[cpu].cpu;

	struct device *s = &c->dev;

	struct device *s = &per_cpu(cpu_device, cpu)->dev;

	int err = 0;



	switch (action & ~CPU_TASKS_FROZEN) {
@@ -1102,7 +1102,7 @@ static int smp_add_present_cpu(int cpu) 
	c = kzalloc(sizeof(*c), GFP_KERNEL);

	if (!c)

		return -ENOMEM;

	pcpu_devices[cpu].cpu = c;

	per_cpu(cpu_device, cpu) = c;

	s = &c->dev;

	c->hotpluggable = 1;

	rc = register_cpu(c, cpu);