From 22fc6eccbf4ce4eb6265e6ada7b50a7b9cc57d05 Mon Sep 17 00:00:00 2001 From: Ravikiran G Thirumalai Date: Sun, 8 Jan 2006 01:01:27 -0800 Subject: [PATCH] Change maxaligned_in_smp alignemnt macros to internodealigned_in_smp macros ____cacheline_maxaligned_in_smp is currently used to align critical structures and avoid false sharing. It uses per-arch L1_CACHE_SHIFT_MAX and people find L1_CACHE_SHIFT_MAX useless. However, we have been using ____cacheline_maxaligned_in_smp to align structures on the internode cacheline size. As per Andi's suggestion, following patch kills ____cacheline_maxaligned_in_smp and introduces INTERNODE_CACHE_SHIFT, which defaults to L1_CACHE_SHIFT for all arches. Arches needing L3/Internode cacheline alignment can define INTERNODE_CACHE_SHIFT in the arch asm/cache.h. Patch replaces ____cacheline_maxaligned_in_smp with ____cacheline_internodealigned_in_smp With this patch, L1_CACHE_SHIFT_MAX can be killed Signed-off-by: Ravikiran Thirumalai Signed-off-by: Shai Fultheim Signed-off-by: Andi Kleen Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/cache.h | 17 +++++++++++++---- 1 file changed, 13 insertions(+), 4 deletions(-) (limited to 'include/linux/cache.h') diff --git a/include/linux/cache.h b/include/linux/cache.h index 0b7ecf3af78a..ffe52210fc4f 100644 --- a/include/linux/cache.h +++ b/include/linux/cache.h @@ -45,12 +45,21 @@ #endif /* CONFIG_SMP */ #endif -#if !defined(____cacheline_maxaligned_in_smp) +/* + * The maximum alignment needed for some critical structures + * These could be inter-node cacheline sizes/L3 cacheline + * size etc. Define this in asm/cache.h for your arch + */ +#ifndef INTERNODE_CACHE_SHIFT +#define INTERNODE_CACHE_SHIFT L1_CACHE_SHIFT +#endif + +#if !defined(____cacheline_internodealigned_in_smp) #if defined(CONFIG_SMP) -#define ____cacheline_maxaligned_in_smp \ - __attribute__((__aligned__(1 << (L1_CACHE_SHIFT_MAX)))) +#define ____cacheline_internodealigned_in_smp \ + __attribute__((__aligned__(1 << (INTERNODE_CACHE_SHIFT)))) #else -#define ____cacheline_maxaligned_in_smp +#define ____cacheline_internodealigned_in_smp #endif #endif -- cgit v1.2.3