This patch adds the basic infrastructure for alloc / free operations on pointer arrays. It includes a fallback function that can perform the array operations using the single alloc and free that every slab allocator performs.
Allocators must define _HAVE_SLAB_ALLOCATOR_OPERATIONS in their header files in order to implement their own fast version for these array operations. Array operations allow a reduction of the processing overhead during allocation and therefore speed up acquisition of larger amounts of objects. Signed-off-by: Christoph Lameter <[email protected]> Index: linux/include/linux/slab.h =================================================================== --- linux.orig/include/linux/slab.h +++ linux/include/linux/slab.h @@ -123,6 +123,7 @@ struct kmem_cache *memcg_create_kmem_cac void kmem_cache_destroy(struct kmem_cache *); int kmem_cache_shrink(struct kmem_cache *); void kmem_cache_free(struct kmem_cache *, void *); +void kmem_cache_free_array(struct kmem_cache *, size_t, void **); /* * Please use this macro to create slab caches. Simply specify the @@ -290,6 +291,39 @@ static __always_inline int kmalloc_index void *__kmalloc(size_t size, gfp_t flags); void *kmem_cache_alloc(struct kmem_cache *, gfp_t flags); +/* + * Additional flags that may be specified in kmem_cache_alloc_array()'s + * gfp flags. + * + * If no flags are specified then kmem_cache_alloc_array() will first exhaust + * the partial slab page lists of the local node, then allocate new pages from + * the page allocator as long as more than objects per page objects are wanted + * and fill up the rest from local cached objects. If that is not enough then + * the remaining objects will be allocated via kmem_cache_alloc() + */ + +/* Use objects cached for the processor */ +#define GFP_SLAB_ARRAY_LOCAL ((__force gfp_t)0x40000000) + +/* Use slabs from this node that have objects available */ +#define GFP_SLAB_ARRAY_PARTIAL ((__force gfp_t)0x20000000) + +/* Allocate new slab pages from page allocator */ +#define GFP_SLAB_ARRAY_NEW ((__force gfp_t)0x10000000) + +/* + * If other measures did not fill up the array to the full count + * requested then use kmem_cache_alloc to ensure the number of + * objects requested is allocated. + * If this flag is not set then the the allocation may return + * less than specified if there are no more objects of the + * particular type. + */ +#define GFP_SLAB_ARRAY_FULL_COUNT ((__force gfp_t)0x08000000) + +int kmem_cache_alloc_array(struct kmem_cache *, gfp_t gfpflags, + size_t nr, void **); + #ifdef CONFIG_NUMA void *__kmalloc_node(size_t size, gfp_t flags, int node); void *kmem_cache_alloc_node(struct kmem_cache *, gfp_t flags, int node); Index: linux/mm/slab_common.c =================================================================== --- linux.orig/mm/slab_common.c +++ linux/mm/slab_common.c @@ -105,6 +105,92 @@ static inline int kmem_cache_sanity_chec } #endif +#ifndef _HAVE_SLAB_ALLOCATOR_ARRAY_OPERATIONS +int kmem_cache_alloc_array(struct kmem_cache *s, + gfp_t flags, size_t nr, void **p) +{ + int i; + + /* + * Generic code does not support the processing of the + * special allocation flags. So strip them off the mask. + */ + flags &= __GFP_BITS_MASK; + + for (i = 0; i < nr; i++) { + void *x = kmem_cache_alloc(s, flags); + + if (!x) + return i; + p[i] = x; + } + return nr; +} +EXPORT_SYMBOL(kmem_cache_alloc_array); + +void kmem_cache_free_array(struct kmem_cache *s, size_t nr, void **p) +{ + int i; + + for (i = 0; i < nr; i++) + kmem_cache_free(s, p[i]); +} +EXPORT_SYMBOL(kmem_cache_free_array); +#else + +int kmem_cache_alloc_array(struct kmem_cache *s, + gfp_t flags, size_t nr, void **p) +{ + int i = 0; + + /* + * Setup the default operation mode if no special GFP_SLAB_* + * flags were specified. + */ + if ((flags & ~__GFP_BITS_MASK) == 0) + flags |= GFP_SLAB_ARRAY_PARTIAL | + GFP_SLAB_ARRAY_NEW | + GFP_SLAB_ARRAY_LOCAL | + GFP_SLAB_ARRAY_FULL_COUNT; + + /* + * First extract objects from partial lists in order to + * avoid further fragmentation. + */ + if (flags & GFP_SLAB_ARRAY_PARTIAL) + i += slab_array_alloc_from_partial(s, nr - i, p + i); + + /* + * If there are still a larger number of objects to be allocated + * use the page allocator directly. + */ + if ((flags & GFP_SLAB_ARRAY_NEW) && nr - i > objects_per_slab_page(s)) + i += slab_array_alloc_from_page_allocator(s, + flags & __GFP_BITS_MASK, + nr - i, p + i); + + /* Get per cpu objects that may be available */ + if (flags & GFP_SLAB_ARRAY_LOCAL) + i += slab_array_alloc_from_local(s, nr - i, p + i); + + /* + * If a fully filled array has been requested then fill it + * up if there are objects missing using the regular kmem_cache_alloc() + */ + if (flags & GFP_SLAB_ARRAY_FULL_COUNT) + while (i < nr) { + void *x = kmem_cache_alloc(s, + flags & __GFP_BITS_MASK); + if (!x) + return i; + p[i++] = x; + } + + return i; +} +EXPORT_SYMBOL(kmem_cache_alloc_array); +#endif + #ifdef CONFIG_MEMCG_KMEM static int memcg_alloc_cache_params(struct mem_cgroup *memcg, struct kmem_cache *s, struct kmem_cache *root_cache) Index: linux/mm/slab.h =================================================================== --- linux.orig/mm/slab.h +++ linux/mm/slab.h @@ -69,6 +69,10 @@ extern struct kmem_cache *kmem_cache; unsigned long calculate_alignment(unsigned long flags, unsigned long align, unsigned long size); +/* Determine the number of objects per slab page */ +unsigned objects_per_slab_page(struct kmem_cache *); + + #ifndef CONFIG_SLOB /* Kmalloc array related functions */ void create_kmalloc_caches(unsigned long); @@ -362,4 +366,10 @@ void *slab_next(struct seq_file *m, void void slab_stop(struct seq_file *m, void *p); int memcg_slab_show(struct seq_file *m, void *p); + +int slab_array_alloc_from_partial(struct kmem_cache *s, size_t nr, void **p); +int slab_array_alloc_from_local(struct kmem_cache *s, size_t nr, void **p); +int slab_array_alloc_from_page_allocator(struct kmem_cache *s, gfp_t flags, + size_t nr, void **p); + #endif /* MM_SLAB_H */ Index: linux/mm/slub.c =================================================================== --- linux.orig/mm/slub.c +++ linux/mm/slub.c @@ -332,6 +332,11 @@ static inline int oo_objects(struct kmem return x.x & OO_MASK; } +unsigned objects_per_slab_page(struct kmem_cache *s) +{ + return oo_objects(s->oo); +} + /* * Per slab locking using the pagelock */ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
