[RFC] Cleanup slab headers / API to allow easy addition of new slaballocators
From: Christoph Lameter
Date: Fri Dec 08 2006 - 14:13:00 EST
This is a response to an earlier discussion on linux-mm about splitting
slab.h components per allocator. Patch is against 2.6.19-git11.
See http://marc.theaimsgroup.com/?l=linux-mm&m=116469577431008&w=2
This patch cleans up the slab header definitions. We define the common
functions of slob and slab in slab.h and put the extra definitions needed
for slab's kmalloc implementations in <linux/slab_def.h>. In order to get
a greater set of common functions we add several empty functions to slob.c
and also rename slob's kmalloc to __kmalloc.
Slob does not need any special definitions since we introduce a fallback
case. If there is no need for a slab implementation to provide its own
kmalloc mess^H^H^Hacros then we simply fall back to __kmalloc functions.
That is sufficient for SLOB.
Sort the function in slab.h according to their functionality. First the
functions operating on struct kmem_cache * then the kmalloc related
functions followed by special debug and fallback definitions.
Also redo a lot of comments.
Signed-off-by: Christoph Lameter <clameter@xxxxxxx>?
Index: linux-2.6/include/linux/slab.h
===================================================================
--- linux-2.6.orig/include/linux/slab.h 2006-12-08 09:17:10.000000000 -0800
+++ linux-2.6/include/linux/slab.h 2006-12-08 10:52:40.000000000 -0800
@@ -1,7 +1,9 @@
/*
- * linux/include/linux/slab.h
- * Written by Mark Hemment, 1996.
- * (markhe@xxxxxxxxxxxxxxxxx)
+ * Written by Mark Hemment, 1996 (markhe@xxxxxxxxxxxxxxxxx).
+ *
+ * (C) SGI 2006, Christoph Lameter <clameter@xxxxxxx>
+ * Cleaned up and restructured to ease the addition of alternative
+ * implementations of SLAB allocators.
*/
#ifndef _LINUX_SLAB_H
@@ -10,64 +12,99 @@
#ifdef __KERNEL__
#include <linux/gfp.h>
-#include <linux/init.h>
#include <linux/types.h>
-#include <asm/page.h> /* kmalloc_sizes.h needs PAGE_SIZE */
-#include <asm/cache.h> /* kmalloc_sizes.h needs L1_CACHE_BYTES */
-#include <linux/compiler.h>
-/* kmem_cache_t exists for legacy reasons and is not used by code in mm */
typedef struct kmem_cache kmem_cache_t __deprecated;
-/* flags to pass to kmem_cache_create().
- * The first 3 are only valid when the allocator as been build
- * SLAB_DEBUG_SUPPORT.
- */
-#define SLAB_DEBUG_FREE 0x00000100UL /* Peform (expensive) checks on free */
-#define SLAB_DEBUG_INITIAL 0x00000200UL /* Call constructor (as verifier) */
-#define SLAB_RED_ZONE 0x00000400UL /* Red zone objs in a cache */
-#define SLAB_POISON 0x00000800UL /* Poison objects */
-#define SLAB_HWCACHE_ALIGN 0x00002000UL /* align objs on a h/w cache lines */
-#define SLAB_CACHE_DMA 0x00004000UL /* use GFP_DMA memory */
-#define SLAB_MUST_HWCACHE_ALIGN 0x00008000UL /* force alignment */
-#define SLAB_STORE_USER 0x00010000UL /* store the last owner for bug hunting */
-#define SLAB_RECLAIM_ACCOUNT 0x00020000UL /* track pages allocated to indicate
- what is reclaimable later*/
-#define SLAB_PANIC 0x00040000UL /* panic if kmem_cache_create() fails */
-#define SLAB_DESTROY_BY_RCU 0x00080000UL /* defer freeing pages to RCU */
+/*
+ * Flags to pass to kmem_cache_create().
+ * The ones marked DEBUG are only valid if CONFIG_SLAB_DEBUG is set.
+ */
+#define SLAB_DEBUG_FREE 0x00000100UL /* DEBUG: Perform (expensive) checks on free */
+#define SLAB_DEBUG_INITIAL 0x00000200UL /* DEBUG: Call constructor (as verifier) */
+#define SLAB_RED_ZONE 0x00000400UL /* DEBUG: Red zone objs in a cache */
+#define SLAB_POISON 0x00000800UL /* DEBUG: Poison objects */
+#define SLAB_HWCACHE_ALIGN 0x00002000UL /* Align objs on cache lines */
+#define SLAB_CACHE_DMA 0x00004000UL /* Use GFP_DMA memory */
+#define SLAB_MUST_HWCACHE_ALIGN 0x00008000UL /* Force alignment even if debuggin is active */
+#define SLAB_STORE_USER 0x00010000UL /* DEBUG: Store the last owner for bug hunting */
+#define SLAB_RECLAIM_ACCOUNT 0x00020000UL /* Objects are reclaimable */
+#define SLAB_PANIC 0x00040000UL /* Panic if kmem_cache_create() fails */
+#define SLAB_DESTROY_BY_RCU 0x00080000UL /* Defer freeing slabs to RCU */
#define SLAB_MEM_SPREAD 0x00100000UL /* Spread some memory over cpuset */
-/* flags passed to a constructor func */
-#define SLAB_CTOR_CONSTRUCTOR 0x001UL /* if not set, then deconstructor */
-#define SLAB_CTOR_ATOMIC 0x002UL /* tell constructor it can't sleep */
-#define SLAB_CTOR_VERIFY 0x004UL /* tell constructor it's a verify call */
-
-#ifndef CONFIG_SLOB
+/* Flags passed to a constructor functions */
+#define SLAB_CTOR_CONSTRUCTOR 0x001UL /* If not set, then deconstructor */
+#define SLAB_CTOR_ATOMIC 0x002UL /* Tell constructor it can't sleep */
+#define SLAB_CTOR_VERIFY 0x004UL /* Tell constructor it's a verify call */
-/* prototypes */
-extern void __init kmem_cache_init(void);
+/*
+ * struct kmem_cache related prototypes
+ */
+void __init kmem_cache_init(void);
+extern int slab_is_available(void);
-extern struct kmem_cache *kmem_cache_create(const char *, size_t, size_t,
+struct kmem_cache *kmem_cache_create(const char *, size_t, size_t,
unsigned long,
void (*)(void *, struct kmem_cache *, unsigned long),
void (*)(void *, struct kmem_cache *, unsigned long));
-extern void kmem_cache_destroy(struct kmem_cache *);
-extern int kmem_cache_shrink(struct kmem_cache *);
-extern void *kmem_cache_alloc(struct kmem_cache *, gfp_t);
-extern void *kmem_cache_zalloc(struct kmem_cache *, gfp_t);
-extern void kmem_cache_free(struct kmem_cache *, void *);
-extern unsigned int kmem_cache_size(struct kmem_cache *);
-extern const char *kmem_cache_name(struct kmem_cache *);
-
-/* Size description struct for general caches. */
-struct cache_sizes {
- size_t cs_size;
- struct kmem_cache *cs_cachep;
- struct kmem_cache *cs_dmacachep;
-};
-extern struct cache_sizes malloc_sizes[];
+void kmem_cache_destroy(struct kmem_cache *);
+int kmem_cache_shrink(struct kmem_cache *);
+void *kmem_cache_alloc(struct kmem_cache *, gfp_t);
+void *kmem_cache_zalloc(struct kmem_cache *, gfp_t);
+void kmem_cache_free(struct kmem_cache *, void *);
+unsigned int kmem_cache_size(struct kmem_cache *);
+const char *kmem_cache_name(struct kmem_cache *);
+int kmem_ptr_validate(struct kmem_cache *cachep, void *ptr);
-extern void *__kmalloc(size_t, gfp_t);
+#ifdef CONFIG_NUMA
+extern void *kmem_cache_alloc_node(struct kmem_cache *, gfp_t flags, int node);
+#else
+static inline void *kmem_cache_alloc_node(struct kmem_cache *cachep,
+ gfp_t flags, int node)
+{
+ return kmem_cache_alloc(cachep, flags);
+}
+#endif
+
+/*
+ * Common kmalloc functions provided by all allocators
+ */
+void *__kmalloc(size_t, gfp_t);
+void *__kzalloc(size_t, gfp_t);
+void kfree(const void *);
+unsigned int ksize(const void *);
+
+/**
+ * kcalloc - allocate memory for an array. The memory is set to zero.
+ * @n: number of elements.
+ * @size: element size.
+ * @flags: the type of memory to allocate.
+ */
+static inline void *kcalloc(size_t n, size_t size, gfp_t flags)
+{
+ if (n != 0 && size > ULONG_MAX / n)
+ return NULL;
+ return __kzalloc(n * size, flags);
+}
+
+/*
+ * Allocator specific definitions. These are mainly used to establish optimized
+ * ways to convert kmalloc() calls to kmem_cache_alloc() invocations by selecting
+ * the appropriate general cache at compile time.
+ */
+#ifdef CONFIG_SLAB
+#include <linux/slab_def.h>
+#else
+
+/*
+ * Fallback definitions for an allocator not wanting to provide
+ * its own optimized kmalloc definitions (like SLOB).
+ */
+
+#if defined(CONFIG_NUMA) || defined(CONFIG_DEBUG_SLAB)
+#error "SLAB fallback definitions not usable for NUMA or Slab debug"
+#endif
/**
* kmalloc - allocate memory
@@ -114,29 +151,22 @@
*
* %__GFP_REPEAT - If allocation fails initially, try once more before failing.
*/
-static inline void *kmalloc(size_t size, gfp_t flags)
+void *kmalloc(size_t size, gfp_t flags)
{
- if (__builtin_constant_p(size)) {
- int i = 0;
-#define CACHE(x) \
- if (size <= x) \
- goto found; \
- else \
- i++;
-#include "kmalloc_sizes.h"
-#undef CACHE
- {
- extern void __you_cannot_kmalloc_that_much(void);
- __you_cannot_kmalloc_that_much();
- }
-found:
- return kmem_cache_alloc((flags & GFP_DMA) ?
- malloc_sizes[i].cs_dmacachep :
- malloc_sizes[i].cs_cachep, flags);
- }
return __kmalloc(size, flags);
}
+/**
+ * kzalloc - allocate memory. The memory is set to zero.
+ * @size: how many bytes of memory are required.
+ * @flags: the type of memory to allocate (see kmalloc).
+ */
+void *kzalloc(size_t size, gfp_t flags)
+{
+ return __kzalloc(size, flags);
+}
+#endif
+
/*
* kmalloc_track_caller is a special version of kmalloc that records the
* calling function of the routine calling it for slab leak tracking instead
@@ -145,89 +175,16 @@
* allocator where we care about the real place the memory allocation
* request comes from.
*/
-#ifndef CONFIG_DEBUG_SLAB
-#define kmalloc_track_caller(size, flags) \
- __kmalloc(size, flags)
-#else
+#ifdef CONFIG_DEBUG_SLAB
extern void *__kmalloc_track_caller(size_t, gfp_t, void*);
#define kmalloc_track_caller(size, flags) \
__kmalloc_track_caller(size, flags, __builtin_return_address(0))
-#endif
-
-extern void *__kzalloc(size_t, gfp_t);
-
-/**
- * kzalloc - allocate memory. The memory is set to zero.
- * @size: how many bytes of memory are required.
- * @flags: the type of memory to allocate (see kmalloc).
- */
-static inline void *kzalloc(size_t size, gfp_t flags)
-{
- if (__builtin_constant_p(size)) {
- int i = 0;
-#define CACHE(x) \
- if (size <= x) \
- goto found; \
- else \
- i++;
-#include "kmalloc_sizes.h"
-#undef CACHE
- {
- extern void __you_cannot_kzalloc_that_much(void);
- __you_cannot_kzalloc_that_much();
- }
-found:
- return kmem_cache_zalloc((flags & GFP_DMA) ?
- malloc_sizes[i].cs_dmacachep :
- malloc_sizes[i].cs_cachep, flags);
- }
- return __kzalloc(size, flags);
-}
-
-/**
- * kcalloc - allocate memory for an array. The memory is set to zero.
- * @n: number of elements.
- * @size: element size.
- * @flags: the type of memory to allocate.
- */
-static inline void *kcalloc(size_t n, size_t size, gfp_t flags)
-{
- if (n != 0 && size > ULONG_MAX / n)
- return NULL;
- return kzalloc(n * size, flags);
-}
-
-extern void kfree(const void *);
-extern unsigned int ksize(const void *);
-extern int slab_is_available(void);
+#else
+#define kmalloc_track_caller(size, flags) \
+ __kmalloc(size, flags)
+#endif /* DEBUG_SLAB */
#ifdef CONFIG_NUMA
-extern void *kmem_cache_alloc_node(struct kmem_cache *, gfp_t flags, int node);
-extern void *__kmalloc_node(size_t size, gfp_t flags, int node);
-
-static inline void *kmalloc_node(size_t size, gfp_t flags, int node)
-{
- if (__builtin_constant_p(size)) {
- int i = 0;
-#define CACHE(x) \
- if (size <= x) \
- goto found; \
- else \
- i++;
-#include "kmalloc_sizes.h"
-#undef CACHE
- {
- extern void __you_cannot_kmalloc_that_much(void);
- __you_cannot_kmalloc_that_much();
- }
-found:
- return kmem_cache_alloc_node((flags & GFP_DMA) ?
- malloc_sizes[i].cs_dmacachep :
- malloc_sizes[i].cs_cachep, flags, node);
- }
- return __kmalloc_node(size, flags, node);
-}
-
/*
* kmalloc_node_track_caller is a special version of kmalloc_node that
* records the calling function of the routine calling it for slab leak
@@ -236,70 +193,27 @@
* standard allocator where we care about the real place the memory
* allocation request comes from.
*/
-#ifndef CONFIG_DEBUG_SLAB
-#define kmalloc_node_track_caller(size, flags, node) \
- __kmalloc_node(size, flags, node)
-#else
+#ifdef CONFIG_DEBUG_SLAB
extern void *__kmalloc_node_track_caller(size_t, gfp_t, int, void *);
#define kmalloc_node_track_caller(size, flags, node) \
__kmalloc_node_track_caller(size, flags, node, \
__builtin_return_address(0))
+#else
+#define kmalloc_node_track_caller(size, flags, node) \
+ __kmalloc_node(size, flags, node)
#endif
+
#else /* CONFIG_NUMA */
-static inline void *kmem_cache_alloc_node(struct kmem_cache *cachep,
- gfp_t flags, int node)
-{
- return kmem_cache_alloc(cachep, flags);
-}
-static inline void *kmalloc_node(size_t size, gfp_t flags, int node)
-{
- return kmalloc(size, flags);
-}
#define kmalloc_node_track_caller(size, flags, node) \
kmalloc_track_caller(size, flags)
-#endif
-extern int FASTCALL(kmem_cache_reap(int));
-extern int FASTCALL(kmem_ptr_validate(struct kmem_cache *cachep, void *ptr));
-
-#else /* CONFIG_SLOB */
-
-/* SLOB allocator routines */
-
-void kmem_cache_init(void);
-struct kmem_cache *kmem_cache_create(const char *c, size_t, size_t,
- unsigned long,
- void (*)(void *, struct kmem_cache *, unsigned long),
- void (*)(void *, struct kmem_cache *, unsigned long));
-void kmem_cache_destroy(struct kmem_cache *c);
-void *kmem_cache_alloc(struct kmem_cache *c, gfp_t flags);
-void *kmem_cache_zalloc(struct kmem_cache *, gfp_t);
-void kmem_cache_free(struct kmem_cache *c, void *b);
-const char *kmem_cache_name(struct kmem_cache *);
-void *kmalloc(size_t size, gfp_t flags);
-void *__kzalloc(size_t size, gfp_t flags);
-void kfree(const void *m);
-unsigned int ksize(const void *m);
-unsigned int kmem_cache_size(struct kmem_cache *c);
-
-static inline void *kcalloc(size_t n, size_t size, gfp_t flags)
+static inline void *kmalloc_node(size_t size, gfp_t flags, int node)
{
- return __kzalloc(n * size, flags);
+ return kmalloc(size, flags);
}
-#define kmem_cache_shrink(d) (0)
-#define kmem_cache_reap(a)
-#define kmem_ptr_validate(a, b) (0)
-#define kmem_cache_alloc_node(c, f, n) kmem_cache_alloc(c, f)
-#define kmalloc_node(s, f, n) kmalloc(s, f)
-#define kzalloc(s, f) __kzalloc(s, f)
-#define kmalloc_track_caller kmalloc
-
-#define kmalloc_node_track_caller kmalloc_node
-
-#endif /* CONFIG_SLOB */
-
+#endif /* !CONFIG_NUMA */
#endif /* __KERNEL__ */
-
#endif /* _LINUX_SLAB_H */
+
Index: linux-2.6/mm/slob.c
===================================================================
--- linux-2.6.orig/mm/slob.c 2006-12-08 09:17:10.000000000 -0800
+++ linux-2.6/mm/slob.c 2006-12-08 11:02:02.000000000 -0800
@@ -157,7 +157,7 @@
return order;
}
-void *kmalloc(size_t size, gfp_t gfp)
+void *__kmalloc(size_t size, gfp_t gfp)
{
slob_t *m;
bigblock_t *bb;
@@ -186,8 +186,7 @@
slob_free(bb, sizeof(bigblock_t));
return 0;
}
-
-EXPORT_SYMBOL(kmalloc);
+EXPORT_SYMBOL(__kmalloc);
void kfree(const void *block)
{
@@ -329,6 +328,17 @@
static struct timer_list slob_timer = TIMER_INITIALIZER(
(void (*)(unsigned long))kmem_cache_init, 0, 0);
+int kmem_cache_shrink(struct kmem_cache *d)
+{
+ return 0;
+}
+EXPORT_SYMBOL(kmem_cache_shrink);
+
+int kmem_ptr_validate(struct kmem_cache *a, void *b)
+{
+ return 0;
+}
+
void kmem_cache_init(void)
{
void *p = slob_alloc(PAGE_SIZE, 0, PAGE_SIZE-1);
Index: linux-2.6/include/linux/slab_def.h
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ linux-2.6/include/linux/slab_def.h 2006-12-08 10:57:05.000000000 -0800
@@ -0,0 +1,100 @@
+#ifndef _LINUX_SLAB_DEF_H
+#define _LINUX_SLAB_DEF_H
+
+/*
+ * Definitions unique to the original Linux SLAB allocator.
+ *
+ * What we provide here is a way to optimize the frequent kmalloc
+ * calls in the kernel by selecting the appropriate general cache
+ * if kmalloc was called with a size that can be established at
+ * compile time.
+ */
+
+#include <linux/init.h>
+#include <asm/page.h> /* kmalloc_sizes.h needs PAGE_SIZE */
+#include <asm/cache.h> /* kmalloc_sizes.h needs L1_CACHE_BYTES */
+#include <linux/compiler.h>
+
+/* Size description struct for general caches. */
+struct cache_sizes {
+ size_t cs_size;
+ struct kmem_cache *cs_cachep;
+ struct kmem_cache *cs_dmacachep;
+};
+extern struct cache_sizes malloc_sizes[];
+
+static inline void *kmalloc(size_t size, gfp_t flags)
+{
+ if (__builtin_constant_p(size)) {
+ int i = 0;
+#define CACHE(x) \
+ if (size <= x) \
+ goto found; \
+ else \
+ i++;
+#include "kmalloc_sizes.h"
+#undef CACHE
+ {
+ extern void __you_cannot_kmalloc_that_much(void);
+ __you_cannot_kmalloc_that_much();
+ }
+found:
+ return kmem_cache_alloc((flags & GFP_DMA) ?
+ malloc_sizes[i].cs_dmacachep :
+ malloc_sizes[i].cs_cachep, flags);
+ }
+ return __kmalloc(size, flags);
+}
+
+static inline void *kzalloc(size_t size, gfp_t flags)
+{
+ if (__builtin_constant_p(size)) {
+ int i = 0;
+#define CACHE(x) \
+ if (size <= x) \
+ goto found; \
+ else \
+ i++;
+#include "kmalloc_sizes.h"
+#undef CACHE
+ {
+ extern void __you_cannot_kzalloc_that_much(void);
+ __you_cannot_kzalloc_that_much();
+ }
+found:
+ return kmem_cache_zalloc((flags & GFP_DMA) ?
+ malloc_sizes[i].cs_dmacachep :
+ malloc_sizes[i].cs_cachep, flags);
+ }
+ return __kzalloc(size, flags);
+}
+
+#ifdef CONFIG_NUMA
+extern void *__kmalloc_node(size_t size, gfp_t flags, int node);
+
+static inline void *kmalloc_node(size_t size, gfp_t flags, int node)
+{
+ if (__builtin_constant_p(size)) {
+ int i = 0;
+#define CACHE(x) \
+ if (size <= x) \
+ goto found; \
+ else \
+ i++;
+#include "kmalloc_sizes.h"
+#undef CACHE
+ {
+ extern void __you_cannot_kmalloc_that_much(void);
+ __you_cannot_kmalloc_that_much();
+ }
+found:
+ return kmem_cache_alloc_node((flags & GFP_DMA) ?
+ malloc_sizes[i].cs_dmacachep :
+ malloc_sizes[i].cs_cachep, flags, node);
+ }
+ return __kmalloc_node(size, flags, node);
+}
+
+#endif /* CONFIG_NUMA */
+
+#endif /* _LINUX_SLAB_DEF_H */
-
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