Commit 42f8faec authored by Lai Jiangshan's avatar Lai Jiangshan Committed by Tejun Heo
Browse files

x86: use percpu data for 4k hardirq and softirq stacks 



Impact: economize memory for large NR_CPUS

percpu data is setup earlier than irq, we can use percpu data
to economize memory.

Signed-off-by: default avatarLai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent 58105ef1

arch/x86/kernel/irq_32.c

+15 −14
Original line number Original line Diff line number Diff line
@@ -16,6 +16,7 @@ 
#include <linux/cpu.h>

#include <linux/cpu.h>

#include <linux/delay.h>

#include <linux/delay.h>

#include <linux/uaccess.h>

#include <linux/uaccess.h>

#include <linux/percpu.h>





#include <asm/apic.h>

#include <asm/apic.h>
@@ -55,13 +56,13 @@ static inline void print_stack_overflow(void) { } 
union irq_ctx {

union irq_ctx {

	struct thread_info      tinfo;

	struct thread_info      tinfo;

	u32                     stack[THREAD_SIZE/sizeof(u32)];

	u32                     stack[THREAD_SIZE/sizeof(u32)];

};

} __attribute__((aligned(PAGE_SIZE)));





static union irq_ctx *hardirq_ctx[NR_CPUS] __read_mostly;

static DEFINE_PER_CPU(union irq_ctx *, hardirq_ctx);

static union irq_ctx *softirq_ctx[NR_CPUS] __read_mostly;

static DEFINE_PER_CPU(union irq_ctx *, softirq_ctx);





static char softirq_stack[NR_CPUS * THREAD_SIZE] __page_aligned_bss;

static DEFINE_PER_CPU_PAGE_ALIGNED(union irq_ctx, hardirq_stack);

static char hardirq_stack[NR_CPUS * THREAD_SIZE] __page_aligned_bss;

static DEFINE_PER_CPU_PAGE_ALIGNED(union irq_ctx, softirq_stack);





static void call_on_stack(void *func, void *stack)

static void call_on_stack(void *func, void *stack)

{

{
@@ -81,7 +82,7 @@ execute_on_irq_stack(int overflow, struct irq_desc *desc, int irq) 
	u32 *isp, arg1, arg2;

	u32 *isp, arg1, arg2;





	curctx = (union irq_ctx *) current_thread_info();

	curctx = (union irq_ctx *) current_thread_info();

	irqctx = hardirq_ctx[smp_processor_id()];

	irqctx = __get_cpu_var(hardirq_ctx);





	/*

	/*

	 * this is where we switch to the IRQ stack. However, if we are

	 * this is where we switch to the IRQ stack. However, if we are
@@ -125,34 +126,34 @@ void __cpuinit irq_ctx_init(int cpu) 
{

{

	union irq_ctx *irqctx;

	union irq_ctx *irqctx;





	if (hardirq_ctx[cpu])

	if (per_cpu(hardirq_ctx, cpu))

		return;

		return;





	irqctx = (union irq_ctx*) &hardirq_stack[cpu*THREAD_SIZE];

	irqctx = &per_cpu(hardirq_stack, cpu);

	irqctx->tinfo.task		= NULL;

	irqctx->tinfo.task		= NULL;

	irqctx->tinfo.exec_domain	= NULL;

	irqctx->tinfo.exec_domain	= NULL;

	irqctx->tinfo.cpu		= cpu;

	irqctx->tinfo.cpu		= cpu;

	irqctx->tinfo.preempt_count	= HARDIRQ_OFFSET;

	irqctx->tinfo.preempt_count	= HARDIRQ_OFFSET;

	irqctx->tinfo.addr_limit	= MAKE_MM_SEG(0);

	irqctx->tinfo.addr_limit	= MAKE_MM_SEG(0);





	hardirq_ctx[cpu] = irqctx;

	per_cpu(hardirq_ctx, cpu) = irqctx;





	irqctx = (union irq_ctx *) &softirq_stack[cpu*THREAD_SIZE];

	irqctx = &per_cpu(softirq_stack, cpu);

	irqctx->tinfo.task		= NULL;

	irqctx->tinfo.task		= NULL;

	irqctx->tinfo.exec_domain	= NULL;

	irqctx->tinfo.exec_domain	= NULL;

	irqctx->tinfo.cpu		= cpu;

	irqctx->tinfo.cpu		= cpu;

	irqctx->tinfo.preempt_count	= 0;

	irqctx->tinfo.preempt_count	= 0;

	irqctx->tinfo.addr_limit	= MAKE_MM_SEG(0);

	irqctx->tinfo.addr_limit	= MAKE_MM_SEG(0);





	softirq_ctx[cpu] = irqctx;

	per_cpu(softirq_ctx, cpu) = irqctx;





	printk(KERN_DEBUG "CPU %u irqstacks, hard=%p soft=%p\n",

	printk(KERN_DEBUG "CPU %u irqstacks, hard=%p soft=%p\n",

	       cpu, hardirq_ctx[cpu], softirq_ctx[cpu]);

	       cpu, per_cpu(hardirq_ctx, cpu),  per_cpu(softirq_ctx, cpu));

}

}





void irq_ctx_exit(int cpu)

void irq_ctx_exit(int cpu)

{

{

	hardirq_ctx[cpu] = NULL;

	per_cpu(hardirq_ctx, cpu) = NULL;

}

}





asmlinkage void do_softirq(void)

asmlinkage void do_softirq(void)
@@ -169,7 +170,7 @@ asmlinkage void do_softirq(void) 




	if (local_softirq_pending()) {

	if (local_softirq_pending()) {

		curctx = current_thread_info();

		curctx = current_thread_info();

		irqctx = softirq_ctx[smp_processor_id()];

		irqctx = __get_cpu_var(softirq_ctx);

		irqctx->tinfo.task = curctx->task;

		irqctx->tinfo.task = curctx->task;

		irqctx->tinfo.previous_esp = current_stack_pointer;

		irqctx->tinfo.previous_esp = current_stack_pointer;