From fd76bab2fa6d8f3ef6b326a4c6ae442fa21d30a4 Mon Sep 17 00:00:00 2001 From: Pekka Enberg Date: Sun, 6 May 2007 14:48:40 -0700 Subject: slab: introduce krealloc This introduce krealloc() that reallocates memory while keeping the contents unchanged. The allocator avoids reallocation if the new size fits the currently used cache. I also added a simple non-optimized version for mm/slob.c for compatibility. [akpm@linux-foundation.org: fix warnings] Acked-by: Josef Sipek Acked-by: Matt Mackall Acked-by: Christoph Lameter Signed-off-by: Pekka Enberg Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/slab.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'include/linux/slab.h') diff --git a/include/linux/slab.h b/include/linux/slab.h index 1ef822e31c7..2f8f60ff294 100644 --- a/include/linux/slab.h +++ b/include/linux/slab.h @@ -72,8 +72,9 @@ static inline void *kmem_cache_alloc_node(struct kmem_cache *cachep, */ void *__kmalloc(size_t, gfp_t); void *__kzalloc(size_t, gfp_t); +void * __must_check krealloc(const void *, size_t, gfp_t); void kfree(const void *); -unsigned int ksize(const void *); +size_t ksize(const void *); /** * kcalloc - allocate memory for an array. The memory is set to zero. -- cgit v1.2.3 From ac267728f13c55017ed5ee243c9c3166e27ab929 Mon Sep 17 00:00:00 2001 From: Adrian Bunk Date: Sun, 6 May 2007 14:49:12 -0700 Subject: mm/slab.c: proper prototypes Add proper prototypes in include/linux/slab.h. Signed-off-by: Adrian Bunk Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/slab.h | 3 +++ 1 file changed, 3 insertions(+) (limited to 'include/linux/slab.h') diff --git a/include/linux/slab.h b/include/linux/slab.h index 2f8f60ff294..f9ed9346bfd 100644 --- a/include/linux/slab.h +++ b/include/linux/slab.h @@ -219,6 +219,9 @@ extern void *__kmalloc_node_track_caller(size_t, gfp_t, int, void *); #endif /* DEBUG_SLAB */ +extern const struct seq_operations slabinfo_op; +ssize_t slabinfo_write(struct file *, const char __user *, size_t, loff_t *); + #endif /* __KERNEL__ */ #endif /* _LINUX_SLAB_H */ -- cgit v1.2.3 From 81819f0fc8285a2a5a921c019e3e3d7b6169d225 Mon Sep 17 00:00:00 2001 From: Christoph Lameter Date: Sun, 6 May 2007 14:49:36 -0700 Subject: SLUB core This is a new slab allocator which was motivated by the complexity of the existing code in mm/slab.c. It attempts to address a variety of concerns with the existing implementation. A. Management of object queues A particular concern was the complex management of the numerous object queues in SLAB. SLUB has no such queues. Instead we dedicate a slab for each allocating CPU and use objects from a slab directly instead of queueing them up. B. Storage overhead of object queues SLAB Object queues exist per node, per CPU. The alien cache queue even has a queue array that contain a queue for each processor on each node. For very large systems the number of queues and the number of objects that may be caught in those queues grows exponentially. On our systems with 1k nodes / processors we have several gigabytes just tied up for storing references to objects for those queues This does not include the objects that could be on those queues. One fears that the whole memory of the machine could one day be consumed by those queues. C. SLAB meta data overhead SLAB has overhead at the beginning of each slab. This means that data cannot be naturally aligned at the beginning of a slab block. SLUB keeps all meta data in the corresponding page_struct. Objects can be naturally aligned in the slab. F.e. a 128 byte object will be aligned at 128 byte boundaries and can fit tightly into a 4k page with no bytes left over. SLAB cannot do this. D. SLAB has a complex cache reaper SLUB does not need a cache reaper for UP systems. On SMP systems the per CPU slab may be pushed back into partial list but that operation is simple and does not require an iteration over a list of objects. SLAB expires per CPU, shared and alien object queues during cache reaping which may cause strange hold offs. E. SLAB has complex NUMA policy layer support SLUB pushes NUMA policy handling into the page allocator. This means that allocation is coarser (SLUB does interleave on a page level) but that situation was also present before 2.6.13. SLABs application of policies to individual slab objects allocated in SLAB is certainly a performance concern due to the frequent references to memory policies which may lead a sequence of objects to come from one node after another. SLUB will get a slab full of objects from one node and then will switch to the next. F. Reduction of the size of partial slab lists SLAB has per node partial lists. This means that over time a large number of partial slabs may accumulate on those lists. These can only be reused if allocator occur on specific nodes. SLUB has a global pool of partial slabs and will consume slabs from that pool to decrease fragmentation. G. Tunables SLAB has sophisticated tuning abilities for each slab cache. One can manipulate the queue sizes in detail. However, filling the queues still requires the uses of the spin lock to check out slabs. SLUB has a global parameter (min_slab_order) for tuning. Increasing the minimum slab order can decrease the locking overhead. The bigger the slab order the less motions of pages between per CPU and partial lists occur and the better SLUB will be scaling. G. Slab merging We often have slab caches with similar parameters. SLUB detects those on boot up and merges them into the corresponding general caches. This leads to more effective memory use. About 50% of all caches can be eliminated through slab merging. This will also decrease slab fragmentation because partial allocated slabs can be filled up again. Slab merging can be switched off by specifying slub_nomerge on boot up. Note that merging can expose heretofore unknown bugs in the kernel because corrupted objects may now be placed differently and corrupt differing neighboring objects. Enable sanity checks to find those. H. Diagnostics The current slab diagnostics are difficult to use and require a recompilation of the kernel. SLUB contains debugging code that is always available (but is kept out of the hot code paths). SLUB diagnostics can be enabled via the "slab_debug" option. Parameters can be specified to select a single or a group of slab caches for diagnostics. This means that the system is running with the usual performance and it is much more likely that race conditions can be reproduced. I. Resiliency If basic sanity checks are on then SLUB is capable of detecting common error conditions and recover as best as possible to allow the system to continue. J. Tracing Tracing can be enabled via the slab_debug=T, option during boot. SLUB will then protocol all actions on that slabcache and dump the object contents on free. K. On demand DMA cache creation. Generally DMA caches are not needed. If a kmalloc is used with __GFP_DMA then just create this single slabcache that is needed. For systems that have no ZONE_DMA requirement the support is completely eliminated. L. Performance increase Some benchmarks have shown speed improvements on kernbench in the range of 5-10%. The locking overhead of slub is based on the underlying base allocation size. If we can reliably allocate larger order pages then it is possible to increase slub performance much further. The anti-fragmentation patches may enable further performance increases. Tested on: i386 UP + SMP, x86_64 UP + SMP + NUMA emulation, IA64 NUMA + Simulator SLUB Boot options slub_nomerge Disable merging of slabs slub_min_order=x Require a minimum order for slab caches. This increases the managed chunk size and therefore reduces meta data and locking overhead. slub_min_objects=x Mininum objects per slab. Default is 8. slub_max_order=x Avoid generating slabs larger than order specified. slub_debug Enable all diagnostics for all caches slub_debug= Enable selective options for all caches slub_debug=, Enable selective options for a certain set of caches Available Debug options F Double Free checking, sanity and resiliency R Red zoning P Object / padding poisoning U Track last free / alloc T Trace all allocs / frees (only use for individual slabs). To use SLUB: Apply this patch and then select SLUB as the default slab allocator. [hugh@veritas.com: fix an oops-causing locking error] [akpm@linux-foundation.org: various stupid cleanups and small fixes] Signed-off-by: Christoph Lameter Signed-off-by: Hugh Dickins Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/slab.h | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) (limited to 'include/linux/slab.h') diff --git a/include/linux/slab.h b/include/linux/slab.h index f9ed9346bfd..67425c277e1 100644 --- a/include/linux/slab.h +++ b/include/linux/slab.h @@ -32,6 +32,7 @@ typedef struct kmem_cache kmem_cache_t __deprecated; #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 */ +#define SLAB_TRACE 0x00200000UL /* Trace allocations and frees */ /* Flags passed to a constructor functions */ #define SLAB_CTOR_CONSTRUCTOR 0x001UL /* If not set, then deconstructor */ @@ -42,7 +43,7 @@ typedef struct kmem_cache kmem_cache_t __deprecated; * struct kmem_cache related prototypes */ void __init kmem_cache_init(void); -extern int slab_is_available(void); +int slab_is_available(void); struct kmem_cache *kmem_cache_create(const char *, size_t, size_t, unsigned long, @@ -95,9 +96,14 @@ static inline void *kcalloc(size_t n, size_t size, gfp_t flags) * the appropriate general cache at compile time. */ -#ifdef CONFIG_SLAB +#if defined(CONFIG_SLAB) || defined(CONFIG_SLUB) +#ifdef CONFIG_SLUB +#include +#else #include +#endif /* !CONFIG_SLUB */ #else + /* * Fallback definitions for an allocator not wanting to provide * its own optimized kmalloc definitions (like SLOB). @@ -184,7 +190,7 @@ static inline void *__kmalloc_node(size_t size, gfp_t flags, int node) * allocator where we care about the real place the memory allocation * request comes from. */ -#ifdef CONFIG_DEBUG_SLAB +#if defined(CONFIG_DEBUG_SLAB) || defined(CONFIG_SLUB) 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)) @@ -202,7 +208,7 @@ extern void *__kmalloc_track_caller(size_t, gfp_t, void*); * standard allocator where we care about the real place the memory * allocation request comes from. */ -#ifdef CONFIG_DEBUG_SLAB +#if defined(CONFIG_DEBUG_SLAB) || defined(CONFIG_SLUB) 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, \ -- cgit v1.2.3 From 5af60839909b8e3b28ca7cd7912fa0b23475617f Mon Sep 17 00:00:00 2001 From: Christoph Lameter Date: Sun, 6 May 2007 14:49:56 -0700 Subject: slab allocators: Remove obsolete SLAB_MUST_HWCACHE_ALIGN This patch was recently posted to lkml and acked by Pekka. The flag SLAB_MUST_HWCACHE_ALIGN is 1. Never checked by SLAB at all. 2. A duplicate of SLAB_HWCACHE_ALIGN for SLUB 3. Fulfills the role of SLAB_HWCACHE_ALIGN for SLOB. The only remaining use is in sparc64 and ppc64 and their use there reflects some earlier role that the slab flag once may have had. If its specified then SLAB_HWCACHE_ALIGN is also specified. The flag is confusing, inconsistent and has no purpose. Remove it. Acked-by: Pekka Enberg Signed-off-by: Christoph Lameter Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/slab.h | 1 - 1 file changed, 1 deletion(-) (limited to 'include/linux/slab.h') diff --git a/include/linux/slab.h b/include/linux/slab.h index 67425c277e1..a9befa50d3e 100644 --- a/include/linux/slab.h +++ b/include/linux/slab.h @@ -26,7 +26,6 @@ typedef struct kmem_cache kmem_cache_t __deprecated; #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 */ -- cgit v1.2.3 From 0a31bd5f2bbb6473ef9d24f0063ca91cfa678b64 Mon Sep 17 00:00:00 2001 From: Christoph Lameter Date: Sun, 6 May 2007 14:49:57 -0700 Subject: KMEM_CACHE(): simplify slab cache creation This patch provides a new macro KMEM_CACHE(, ) to simplify slab creation. KMEM_CACHE creates a slab with the name of the struct, with the size of the struct and with the alignment of the struct. Additional slab flags may be specified if necessary. Example struct test_slab { int a,b,c; struct list_head; } __cacheline_aligned_in_smp; test_slab_cache = KMEM_CACHE(test_slab, SLAB_PANIC) will create a new slab named "test_slab" of the size sizeof(struct test_slab) and aligned to the alignment of test slab. If it fails then we panic. Signed-off-by: Christoph Lameter Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/slab.h | 12 ++++++++++++ 1 file changed, 12 insertions(+) (limited to 'include/linux/slab.h') diff --git a/include/linux/slab.h b/include/linux/slab.h index a9befa50d3e..e14b4c338b8 100644 --- a/include/linux/slab.h +++ b/include/linux/slab.h @@ -57,6 +57,18 @@ unsigned int kmem_cache_size(struct kmem_cache *); const char *kmem_cache_name(struct kmem_cache *); int kmem_ptr_validate(struct kmem_cache *cachep, const void *ptr); +/* + * Please use this macro to create slab caches. Simply specify the + * name of the structure and maybe some flags that are listed above. + * + * The alignment of the struct determines object alignment. If you + * f.e. add ____cacheline_aligned_in_smp to the struct declaration + * then the objects will be properly aligned in SMP configurations. + */ +#define KMEM_CACHE(__struct, __flags) kmem_cache_create(#__struct,\ + sizeof(struct __struct), __alignof__(struct __struct),\ + (__flags), NULL, NULL) + #ifdef CONFIG_NUMA extern void *kmem_cache_alloc_node(struct kmem_cache *, gfp_t flags, int node); #else -- cgit v1.2.3 From 50953fe9e00ebbeffa032a565ab2f08312d51a87 Mon Sep 17 00:00:00 2001 From: Christoph Lameter Date: Sun, 6 May 2007 14:50:16 -0700 Subject: slab allocators: Remove SLAB_DEBUG_INITIAL flag I have never seen a use of SLAB_DEBUG_INITIAL. It is only supported by SLAB. I think its purpose was to have a callback after an object has been freed to verify that the state is the constructor state again? The callback is performed before each freeing of an object. I would think that it is much easier to check the object state manually before the free. That also places the check near the code object manipulation of the object. Also the SLAB_DEBUG_INITIAL callback is only performed if the kernel was compiled with SLAB debugging on. If there would be code in a constructor handling SLAB_DEBUG_INITIAL then it would have to be conditional on SLAB_DEBUG otherwise it would just be dead code. But there is no such code in the kernel. I think SLUB_DEBUG_INITIAL is too problematic to make real use of, difficult to understand and there are easier ways to accomplish the same effect (i.e. add debug code before kfree). There is a related flag SLAB_CTOR_VERIFY that is frequently checked to be clear in fs inode caches. Remove the pointless checks (they would even be pointless without removeal of SLAB_DEBUG_INITIAL) from the fs constructors. This is the last slab flag that SLUB did not support. Remove the check for unimplemented flags from SLUB. Signed-off-by: Christoph Lameter Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/slab.h | 2 -- 1 file changed, 2 deletions(-) (limited to 'include/linux/slab.h') diff --git a/include/linux/slab.h b/include/linux/slab.h index e14b4c338b8..1ffe0a959cd 100644 --- a/include/linux/slab.h +++ b/include/linux/slab.h @@ -21,7 +21,6 @@ typedef struct kmem_cache kmem_cache_t __deprecated; * 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 */ @@ -36,7 +35,6 @@ typedef struct kmem_cache kmem_cache_t __deprecated; /* 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 */ /* * struct kmem_cache related prototypes -- cgit v1.2.3 From 4f104934591ed98534b3a4c3d17d972b790e9c42 Mon Sep 17 00:00:00 2001 From: Christoph Lameter Date: Sun, 6 May 2007 14:50:17 -0700 Subject: slab allocators: Remove SLAB_CTOR_ATOMIC SLAB_CTOR atomic is never used which is no surprise since I cannot imagine that one would want to do something serious in a constructor or destructor. In particular given that the slab allocators run with interrupts disabled. Actions in constructors and destructors are by their nature very limited and usually do not go beyond initializing variables and list operations. (The i386 pgd ctor and dtors do take a spinlock in constructor and destructor..... I think that is the furthest we go at this point.) There is no flag passed to the destructor so removing SLAB_CTOR_ATOMIC also establishes a certain symmetry. Signed-off-by: Christoph Lameter Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/slab.h | 1 - 1 file changed, 1 deletion(-) (limited to 'include/linux/slab.h') diff --git a/include/linux/slab.h b/include/linux/slab.h index 1ffe0a959cd..71829efc40b 100644 --- a/include/linux/slab.h +++ b/include/linux/slab.h @@ -34,7 +34,6 @@ typedef struct kmem_cache kmem_cache_t __deprecated; /* 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 */ /* * struct kmem_cache related prototypes -- cgit v1.2.3