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Date: Tue, 17 Feb 2009 11:46:42 +0800
From: Lai Jiangshan <laijs@...fujitsu.com>
To: Ingo Molnar <mingo@...e.hu>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: [PATCH] x86,4kstack: use percpu data for hardirq and softirq stack
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: Lai Jiangshan <laijs@...fujitsu.com>
---
irq_32.c | 29 +++++++++++++++--------------
1 file changed, 15 insertions(+), 14 deletions(-)
diff --git a/arch/x86/kernel/irq_32.c b/arch/x86/kernel/irq_32.c
index 74b9ff7..aafd483 100644
--- a/arch/x86/kernel/irq_32.c
+++ b/arch/x86/kernel/irq_32.c
@@ -16,6 +16,7 @@
#include <linux/cpu.h>
#include <linux/delay.h>
#include <linux/uaccess.h>
+#include <linux/percpu.h>
#include <asm/apic.h>
@@ -55,13 +56,13 @@ static inline void print_stack_overflow(void) { }
union irq_ctx {
struct thread_info tinfo;
u32 stack[THREAD_SIZE/sizeof(u32)];
-};
+} __attribute__((aligned(PAGE_SIZE)));
-static union irq_ctx *hardirq_ctx[NR_CPUS] __read_mostly;
-static union irq_ctx *softirq_ctx[NR_CPUS] __read_mostly;
+static DEFINE_PER_CPU(union irq_ctx *, hardirq_ctx);
+static DEFINE_PER_CPU(union irq_ctx *, softirq_ctx);
-static char softirq_stack[NR_CPUS * THREAD_SIZE] __page_aligned_bss;
-static char hardirq_stack[NR_CPUS * THREAD_SIZE] __page_aligned_bss;
+static DEFINE_PER_CPU_PAGE_ALIGNED(union irq_ctx, hardirq_stack);
+static DEFINE_PER_CPU_PAGE_ALIGNED(union irq_ctx, softirq_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;
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
@@ -125,34 +126,34 @@ void __cpuinit irq_ctx_init(int cpu)
{
union irq_ctx *irqctx;
- if (hardirq_ctx[cpu])
+ if (per_cpu(hardirq_ctx, cpu))
return;
- irqctx = (union irq_ctx*) &hardirq_stack[cpu*THREAD_SIZE];
+ irqctx = &per_cpu(hardirq_stack, cpu);
irqctx->tinfo.task = NULL;
irqctx->tinfo.exec_domain = NULL;
irqctx->tinfo.cpu = cpu;
irqctx->tinfo.preempt_count = HARDIRQ_OFFSET;
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.exec_domain = NULL;
irqctx->tinfo.cpu = cpu;
irqctx->tinfo.preempt_count = 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",
- cpu, hardirq_ctx[cpu], softirq_ctx[cpu]);
+ cpu, per_cpu(hardirq_ctx, cpu), per_cpu(softirq_ctx, cpu));
}
void irq_ctx_exit(int cpu)
{
- hardirq_ctx[cpu] = NULL;
+ per_cpu(hardirq_ctx, cpu) = NULL;
}
asmlinkage void do_softirq(void)
@@ -169,7 +170,7 @@ asmlinkage void do_softirq(void)
if (local_softirq_pending()) {
curctx = current_thread_info();
- irqctx = softirq_ctx[smp_processor_id()];
+ irqctx = __get_cpu_var(softirq_ctx);
irqctx->tinfo.task = curctx->task;
irqctx->tinfo.previous_esp = current_stack_pointer;
--
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