[2.6 patch] i386: always use 4k stacks

Adrian Bunk
2005-12-15T21:24:48Z

It seems most problems with 4k stacks are already resolved at least
in -mm.

I'd like to see this patch to always use 4k stacks in -mm now for
finding any remaining problems before submitting this patch for Linus'
tree.

Signed-off-by: Adrian Bunk <bunk@stusta.de>
Acked-by: Arjan van de Ven <arjan@infradead.org>

---

This patch was already sent on:
- 11 Dec 2005
- 5 Dec 2005
- 30 Nov 2005
- 23 Nov 2005
- 14 Nov 2005

arch/i386/Kconfig.debug | 10 ----------
arch/i386/kernel/irq.c | 10 ----------
include/asm-i386/irq.h | 11 +++--------
include/asm-i386/module.h | 8 +-------
include/asm-i386/thread_info.h | 6 +-----
5 files changed, 5 insertions(+), 40 deletions(-)

--- linux-2.6.14-mm2-full/arch/i386/Kconfig.debug.old 2005-11-14 01:30:54.000000000 +0100
+++ linux-2.6.14-mm2-full/arch/i386/Kconfig.debug 2005-11-14 01:31:06.000000000 +0100
@@ -52,16 +52,6 @@
portion of the kernel code won't be covered by a 2MB TLB anymore.
If in doubt, say "N".

-config 4KSTACKS
- bool "Use 4Kb for kernel stacks instead of 8Kb"
- depends on DEBUG_KERNEL
- help
- If you say Y here the kernel will use a 4Kb stacksize for the
- kernel stack attached to each process/thread. This facilitates
- running more threads on a system and also reduces the pressure
- on the VM subsystem for higher order allocations. This option
- will also use IRQ stacks to compensate for the reduced stackspace.
-
config X86_FIND_SMP_CONFIG
bool
depends on X86_LOCAL_APIC || X86_VOYAGER
--- linux-2.6.14-mm2-full/include/asm-i386/irq.h.old 2005-11-14 01:31:18.000000000 +0100
+++ linux-2.6.14-mm2-full/include/asm-i386/irq.h 2005-11-14 01:31:29.000000000 +0100
@@ -27,14 +27,9 @@
# define ARCH_HAS_NMI_WATCHDOG /* See include/linux/nmi.h */
#endif

-#ifdef CONFIG_4KSTACKS
- extern void irq_ctx_init(int cpu);
- extern void irq_ctx_exit(int cpu);
-# define __ARCH_HAS_DO_SOFTIRQ
-#else
-# define irq_ctx_init(cpu) do { } while (0)
-# define irq_ctx_exit(cpu) do { } while (0)
-#endif
+extern void irq_ctx_init(int cpu);
+extern void irq_ctx_exit(int cpu);
+#define __ARCH_HAS_DO_SOFTIRQ

#ifdef CONFIG_IRQBALANCE
extern int irqbalance_disable(char *str);
--- linux-2.6.14-mm2-full/include/asm-i386/thread_info.h.old 2005-11-14 01:31:45.000000000 +0100
+++ linux-2.6.14-mm2-full/include/asm-i386/thread_info.h 2005-11-14 01:32:11.000000000 +0100
@@ -53,11 +53,7 @@
#endif

#define PREEMPT_ACTIVE 0x10000000
-#ifdef CONFIG_4KSTACKS
-#define THREAD_SIZE (4096)
-#else
-#define THREAD_SIZE (8192)
-#endif
+#define THREAD_SIZE (4096)

#define STACK_WARN (THREAD_SIZE/8)
/*
--- linux-2.6.14-mm2-full/include/asm-i386/module.h.old 2005-11-14 01:32:18.000000000 +0100
+++ linux-2.6.14-mm2-full/include/asm-i386/module.h 2005-11-14 01:32:42.000000000 +0100
@@ -64,12 +64,6 @@
#define MODULE_REGPARM ""
#endif

-#ifdef CONFIG_4KSTACKS
-#define MODULE_STACKSIZE "4KSTACKS "
-#else
-#define MODULE_STACKSIZE ""
-#endif
-
-#define MODULE_ARCH_VERMAGIC MODULE_PROC_FAMILY MODULE_REGPARM MODULE_STACKSIZE
+#define MODULE_ARCH_VERMAGIC MODULE_PROC_FAMILY MODULE_REGPARM

#endif /* _ASM_I386_MODULE_H */

--- linux-2.6.15-rc5-mm2-full/arch/i386/kernel/irq.c.old 2005-12-11 15:10:27.000000000 +0100
+++ linux-2.6.15-rc5-mm2-full/arch/i386/kernel/irq.c 2005-12-11 15:11:29.000000000 +0100
@@ -33,7 +33,6 @@
}
#endif

-#ifdef CONFIG_4KSTACKS
/*
* per-CPU IRQ handling contexts (thread information and stack)
*/
@@ -44,7 +43,6 @@

static union irq_ctx *hardirq_ctx[NR_CPUS];
static union irq_ctx *softirq_ctx[NR_CPUS];
-#endif

/*
* do_IRQ handles all normal device IRQ's (the special
@@ -55,10 +53,8 @@
{
/* high bits used in ret_from_ code */
int irq = regs->orig_eax & 0xff;
-#ifdef CONFIG_4KSTACKS
union irq_ctx *curctx, *irqctx;
u32 *isp;
-#endif

irq_enter();
#ifdef CONFIG_DEBUG_STACKOVERFLOW
@@ -76,8 +72,6 @@
}
#endif

-#ifdef CONFIG_4KSTACKS
-
curctx = (union irq_ctx *) current_thread_info();
irqctx = hardirq_ctx[smp_processor_id()];

@@ -104,7 +98,6 @@
: "memory", "cc", "ecx"
);
} else
-#endif
__do_IRQ(irq, regs);

irq_exit();
@@ -114,8 +107,6 @@
return 1;
}

-#ifdef CONFIG_4KSTACKS
-
/*
* These should really be __section__(".bss.page_aligned") as well, but
* gcc's 3.0 and earlier don't handle that correctly.
@@ -200,7 +191,6 @@
}

EXPORT_SYMBOL(do_softirq);
-#endif

/*