On Wed, Jan 03, 2007 at 12:16:35AM -0800, Andrew Morton wrote:
> On Tue, 2 Jan 2007 23:59:23 -0800
> Ravikiran G Thirumalai <[email protected]> wrote:
>
> > The following patches do just that. The first patch is preparatory in nature
> > and the second one changes the x86_64 implementation of spin_lock_irq.
> > Patch passed overnight runs of kernbench and dbench on 4 way x86_64 smp.
>
> The end result of this is, I think, that i386 enables irqs while spinning
> in spin_lock_irqsave() but not while spinning in spin_lock_irq(). And
> x86_64 does the opposite.
No, right now we have on mainline (non PREEMPT case);
i386 x86_64
-----------------------------------------------------------------------------
spin_lock_irq cli when spin cli when spin
spin_lock_irqsave spin with intr enabled spin with intr enabled
The posted patchset changed this to:
i386 x86_64
-----------------------------------------------------------------------------
spin_lock_irq cli when spin spin with intr enabled
spin_lock_irqsave spin with intr enabled spin with intr enabled
>
> Odd, isn't it?
Well we just implemented the x86_64 part. Here goes the i386 part as well for
spin_lock_irq.
i386: Enable interrupts while spinning for a lock with spin_lock_irq
Signed-off-by: Ravikiran Thirumalai <[email protected]>
Index: linux-2.6.20-rc1/include/asm-i386/spinlock.h
===================================================================
--- linux-2.6.20-rc1.orig/include/asm-i386/spinlock.h 2006-12-28 17:18:32.142775000 -0800
+++ linux-2.6.20-rc1/include/asm-i386/spinlock.h 2007-01-03 10:18:32.243662000 -0800
@@ -82,7 +82,22 @@ static inline void __raw_spin_lock_flags
CLI_STI_INPUT_ARGS
: "memory" CLI_STI_CLOBBERS);
}
-# define __raw_spin_lock_irq(lock) __raw_spin_lock(lock)
+
+static inline void __raw_spin_lock_irq(raw_spinlock_t *lock)
+{
+ asm volatile("\n1:\t"
+ LOCK_PREFIX " ; decb %0\n\t"
+ "jns 3f\n"
+ STI_STRING "\n"
+ "2:\t"
+ "rep;nop\n\t"
+ "cmpb $0,%0\n\t"
+ "jle 2b\n\t"
+ CLI_STRING "\n"
+ "jmp 1b\n"
+ "3:\n\t"
+ : "+m" (lock->slock) : : "memory");
+}
#endif
static inline int __raw_spin_trylock(raw_spinlock_t *lock)
-
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