From 0aa817f078b655d0ae36669169d73a5c8a388016 Mon Sep 17 00:00:00 2001 From: Christoph Lameter Date: Wed, 16 May 2007 22:11:01 -0700 Subject: Slab allocators: define common size limitations Currently we have a maze of configuration variables that determine the maximum slab size. Worst of all it seems to vary between SLAB and SLUB. So define a common maximum size for kmalloc. For conveniences sake we use the maximum size ever supported which is 32 MB. We limit the maximum size to a lower limit if MAX_ORDER does not allow such large allocations. For many architectures this patch will have the effect of adding large kmalloc sizes. x86_64 adds 5 new kmalloc sizes. So a small amount of memory will be needed for these caches (contemporary SLAB has dynamically sizeable node and cpu structure so the waste is less than in the past) Most architectures will then be able to allocate object with sizes up to MAX_ORDER. We have had repeated breakage (in fact whenever we doubled the number of supported processors) on IA64 because one or the other struct grew beyond what the slab allocators supported. This will avoid future issues and f.e. avoid fixes for 2k and 4k cpu support. CONFIG_LARGE_ALLOCS is no longer necessary so drop it. It fixes sparc64 with SLAB. Signed-off-by: Christoph Lameter Signed-off-by: "David S. Miller" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/kmalloc_sizes.h | 20 +++++++++++++++----- include/linux/slab.h | 15 +++++++++++++++ include/linux/slub_def.h | 19 ++----------------- 3 files changed, 32 insertions(+), 22 deletions(-) (limited to 'include') diff --git a/include/linux/kmalloc_sizes.h b/include/linux/kmalloc_sizes.h index bda23e00ed7..e576b848ce1 100644 --- a/include/linux/kmalloc_sizes.h +++ b/include/linux/kmalloc_sizes.h @@ -19,17 +19,27 @@ CACHE(32768) CACHE(65536) CACHE(131072) -#if (NR_CPUS > 512) || (MAX_NUMNODES > 256) || !defined(CONFIG_MMU) +#if KMALLOC_MAX_SIZE >= 262144 CACHE(262144) #endif -#ifndef CONFIG_MMU +#if KMALLOC_MAX_SIZE >= 524288 CACHE(524288) +#endif +#if KMALLOC_MAX_SIZE >= 1048576 CACHE(1048576) -#ifdef CONFIG_LARGE_ALLOCS +#endif +#if KMALLOC_MAX_SIZE >= 2097152 CACHE(2097152) +#endif +#if KMALLOC_MAX_SIZE >= 4194304 CACHE(4194304) +#endif +#if KMALLOC_MAX_SIZE >= 8388608 CACHE(8388608) +#endif +#if KMALLOC_MAX_SIZE >= 16777216 CACHE(16777216) +#endif +#if KMALLOC_MAX_SIZE >= 33554432 CACHE(33554432) -#endif /* CONFIG_LARGE_ALLOCS */ -#endif /* CONFIG_MMU */ +#endif diff --git a/include/linux/slab.h b/include/linux/slab.h index 6fb2ae21415..a015236cc57 100644 --- a/include/linux/slab.h +++ b/include/linux/slab.h @@ -73,6 +73,21 @@ static inline void *kmem_cache_alloc_node(struct kmem_cache *cachep, } #endif +/* + * The largest kmalloc size supported by the slab allocators is + * 32 megabyte (2^25) or the maximum allocatable page order if that is + * less than 32 MB. + * + * WARNING: Its not easy to increase this value since the allocators have + * to do various tricks to work around compiler limitations in order to + * ensure proper constant folding. + */ +#define KMALLOC_SHIFT_HIGH ((MAX_ORDER + PAGE_SHIFT) <= 25 ? \ + (MAX_ORDER + PAGE_SHIFT) : 25) + +#define KMALLOC_MAX_SIZE (1UL << KMALLOC_SHIFT_HIGH) +#define KMALLOC_MAX_ORDER (KMALLOC_SHIFT_HIGH - PAGE_SHIFT) + /* * Common kmalloc functions provided by all allocators */ diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h index a9fb92862aa..0764c829d96 100644 --- a/include/linux/slub_def.h +++ b/include/linux/slub_def.h @@ -58,17 +58,6 @@ struct kmem_cache { */ #define KMALLOC_SHIFT_LOW 3 -#ifdef CONFIG_LARGE_ALLOCS -#define KMALLOC_SHIFT_HIGH ((MAX_ORDER + PAGE_SHIFT) =< 25 ? \ - (MAX_ORDER + PAGE_SHIFT - 1) : 25) -#else -#if !defined(CONFIG_MMU) || NR_CPUS > 512 || MAX_NUMNODES > 256 -#define KMALLOC_SHIFT_HIGH 20 -#else -#define KMALLOC_SHIFT_HIGH 18 -#endif -#endif - /* * We keep the general caches in an array of slab caches that are used for * 2^x bytes of allocations. @@ -79,7 +68,7 @@ extern struct kmem_cache kmalloc_caches[KMALLOC_SHIFT_HIGH + 1]; * Sorry that the following has to be that ugly but some versions of GCC * have trouble with constant propagation and loops. */ -static inline int kmalloc_index(int size) +static inline int kmalloc_index(size_t size) { /* * We should return 0 if size == 0 but we use the smallest object @@ -87,7 +76,7 @@ static inline int kmalloc_index(int size) */ WARN_ON_ONCE(size == 0); - if (size > (1 << KMALLOC_SHIFT_HIGH)) + if (size > KMALLOC_MAX_SIZE) return -1; if (size > 64 && size <= 96) @@ -110,17 +99,13 @@ static inline int kmalloc_index(int size) if (size <= 64 * 1024) return 16; if (size <= 128 * 1024) return 17; if (size <= 256 * 1024) return 18; -#if KMALLOC_SHIFT_HIGH > 18 if (size <= 512 * 1024) return 19; if (size <= 1024 * 1024) return 20; -#endif -#if KMALLOC_SHIFT_HIGH > 20 if (size <= 2 * 1024 * 1024) return 21; if (size <= 4 * 1024 * 1024) return 22; if (size <= 8 * 1024 * 1024) return 23; if (size <= 16 * 1024 * 1024) return 24; if (size <= 32 * 1024 * 1024) return 25; -#endif return -1; /* -- cgit v1.2.3