slab: shrink sizeof(struct kmem_cache) (b56efcf0) · Commits · 戴 / test

include/linux/slab_def.h

+13 −13

Original line number	Diff line number	Diff line
		@@ -24,21 +24,19 @@
		*/

		struct kmem_cache {
		/* 1) per-cpu data, touched during every alloc/free */
		struct array_cache *array[NR_CPUS];
		/* 2) Cache tunables. Protected by cache_chain_mutex */
		/* 1) Cache tunables. Protected by cache_chain_mutex */
		unsigned int batchcount;
		unsigned int limit;
		unsigned int shared;

		unsigned int buffer_size;
		u32 reciprocal_buffer_size;
		/* 3) touched by every alloc & free from the backend */
		/* 2) touched by every alloc & free from the backend */

		unsigned int flags; /* constant flags */
		unsigned int num; /* # of objs per slab */

		/* 4) cache_grow/shrink */
		/* 3) cache_grow/shrink */
		/* order of pgs per slab (2^n) */
		unsigned int gfporder;

		@@ -54,11 +52,11 @@ struct kmem_cache {
		/* constructor func */
		void (ctor)(void obj);

		/* 5) cache creation/removal */
		/* 4) cache creation/removal */
		const char *name;
		struct list_head next;

		/* 6) statistics */
		/* 5) statistics */
		#ifdef CONFIG_DEBUG_SLAB
		unsigned long num_active;
		unsigned long num_allocations;
		@@ -85,16 +83,18 @@ struct kmem_cache {
		int obj_size;
		#endif /* CONFIG_DEBUG_SLAB */

		/* 6) per-cpu/per-node data, touched during every alloc/free */
		/*
		* We put nodelists[] at the end of kmem_cache, because we want to size
		* this array to nr_node_ids slots instead of MAX_NUMNODES
		* We put array[] at the end of kmem_cache, because we want to size
		* this array to nr_cpu_ids slots instead of NR_CPUS
		* (see kmem_cache_init())
		* We still use [MAX_NUMNODES] and not [1] or [0] because cache_cache
		* is statically defined, so we reserve the max number of nodes.
		* We still use [NR_CPUS] and not [1] or [0] because cache_cache
		* is statically defined, so we reserve the max number of cpus.
		*/
		struct kmem_list3 *nodelists[MAX_NUMNODES];
		struct kmem_list3 **nodelists;
		struct array_cache *array[NR_CPUS];
		/*
		* Do not add fields after nodelists[]
		* Do not add fields after array[]
		*/
		};

mm/slab.c

+6 −4

Original line number	Diff line number	Diff line
		@@ -574,7 +574,9 @@ static struct arraycache_init initarray_generic =
		{ {0, BOOT_CPUCACHE_ENTRIES, 1, 0} };

		/* internal cache of cache description objs */
		static struct kmem_list3 *cache_cache_nodelists[MAX_NUMNODES];
		static struct kmem_cache cache_cache = {
		.nodelists = cache_cache_nodelists,
		.batchcount = 1,
		.limit = BOOT_CPUCACHE_ENTRIES,
		.shared = 1,
		@@ -1492,10 +1494,9 @@ void __init kmem_cache_init(void)
		cache_cache.nodelists[node] = &initkmem_list3[CACHE_CACHE + node];

		/*
		* struct kmem_cache size depends on nr_node_ids, which
		* can be less than MAX_NUMNODES.
		* struct kmem_cache size depends on nr_node_ids & nr_cpu_ids
		*/
		cache_cache.buffer_size = offsetof(struct kmem_cache, nodelists) +
		cache_cache.buffer_size = offsetof(struct kmem_cache, array[nr_cpu_ids]) +
		nr_node_ids * sizeof(struct kmem_list3 *);
		#if DEBUG
		cache_cache.obj_size = cache_cache.buffer_size;
		@@ -2308,6 +2309,7 @@ kmem_cache_create (const char *name, size_t size, size_t align,
		if (!cachep)
		goto oops;

		cachep->nodelists = (struct kmem_list3 **)&cachep->array[nr_cpu_ids];
		#if DEBUG
		cachep->obj_size = size;

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