From 74f0609526afddd88bef40b651da24f3167b10b2 Mon Sep 17 00:00:00 2001 From: Nick Piggin Date: Thu, 22 May 2008 00:12:31 +1000 Subject: [PATCH] powerpc: Optimise smp_wmb on 64-bit processors For 64-bit processors, lwsync is the recommended method of store/store ordering on caching enabled memory. For those subarchs which have lwsync, use it rather than eieio for smp_wmb. Signed-off-by: Nick Piggin Signed-off-by: Paul Mackerras --- include/asm-powerpc/system.h | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) diff --git a/include/asm-powerpc/system.h b/include/asm-powerpc/system.h index d1ced5029c..145b70f6d2 100644 --- a/include/asm-powerpc/system.h +++ b/include/asm-powerpc/system.h @@ -30,8 +30,8 @@ * * For wmb(), we use sync since wmb is used in drivers to order * stores to system memory with respect to writes to the device. - * However, smp_wmb() can be a lighter-weight eieio barrier on - * SMP since it is only used to order updates to system memory. + * However, smp_wmb() can be a lighter-weight lwsync or eieio barrier + * on SMP since it is only used to order updates to system memory. */ #define mb() __asm__ __volatile__ ("sync" : : : "memory") #define rmb() __asm__ __volatile__ ("sync" : : : "memory") @@ -43,9 +43,16 @@ #ifdef __KERNEL__ #define AT_VECTOR_SIZE_ARCH 6 /* entries in ARCH_DLINFO */ #ifdef CONFIG_SMP + +#ifdef __SUBARCH_HAS_LWSYNC +# define SMPWMB lwsync +#else +# define SMPWMB eieio +#endif + #define smp_mb() mb() #define smp_rmb() rmb() -#define smp_wmb() eieio() +#define smp_wmb() __asm__ __volatile__ (__stringify(SMPWMB) : : :"memory") #define smp_read_barrier_depends() read_barrier_depends() #else #define smp_mb() barrier() -- 2.39.5