freebsd/sys/vm/uma_int.h

/*
 * Copyright (c) 2002, Jeffrey Roberson <jroberson@chesapeake.net>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice unmodified, this list of conditions, and the following
 *    disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * $FreeBSD$
 *
 */

/* 
 *
 * Jeff Roberson <jroberson@chesapeake.net>
 *
 * This file includes definitions, structures, prototypes, and inlines that
 * should not be used outside of the actual implementation of UMA.
 *
 */

/* 
 * Here's a quick description of the relationship between the objects:
 *
 * Zones contain lists of slabs which are stored in either the full bin, empty
 * bin, or partially allocated bin, to reduce fragmentation.  They also contain
 * the user supplied value for size, which is adjusted for alignment purposes
 * and rsize is the result of that.  The zone also stores information for
 * managing a hash of page addresses that maps pages to uma_slab_t structures
 * for pages that don't have embedded uma_slab_t's.
 *  
 * The uma_slab_t may be embedded in a UMA_SLAB_SIZE chunk of memory or it may
 * be allocated off the page from a special slab zone.  The free list within a
 * slab is managed with a linked list of indexes, which are 8 bit values.  If
 * UMA_SLAB_SIZE is defined to be too large I will have to switch to 16bit
 * values.  Currently on alpha you can get 250 or so 32 byte items and on x86
 * you can get 250 or so 16byte items.  For item sizes that would yield more
 * than 10% memory waste we potentially allocate a separate uma_slab_t if this
 * will improve the number of items per slab that will fit.  
 *
 * Other potential space optimizations are storing the 8bit of linkage in space
 * wasted between items due to alignment problems.  This may yield a much better
 * memory footprint for certain sizes of objects.  Another alternative is to
 * increase the UMA_SLAB_SIZE, or allow for dynamic slab sizes.  I prefer
 * dynamic slab sizes because we could stick with 8 bit indexes and only use
 * large slab sizes for zones with a lot of waste per slab.  This may create
 * ineffeciencies in the vm subsystem due to fragmentation in the address space.
 *
 * The only really gross cases, with regards to memory waste, are for those
 * items that are just over half the page size.   You can get nearly 50% waste,
 * so you fall back to the memory footprint of the power of two allocator. I
 * have looked at memory allocation sizes on many of the machines available to
 * me, and there does not seem to be an abundance of allocations at this range
 * so at this time it may not make sense to optimize for it.  This can, of 
 * course, be solved with dynamic slab sizes.
 *
 */

/*
 *	This is the representation for normal (Non OFFPAGE slab)
 *
 *	i == item
 *	s == slab pointer
 *
 *	<----------------  Page (UMA_SLAB_SIZE) ------------------>
 *	___________________________________________________________
 *     | _  _  _  _  _  _  _  _  _  _  _  _  _  _  _   ___________ |
 *     ||i||i||i||i||i||i||i||i||i||i||i||i||i||i||i| |slab header||
 *     ||_||_||_||_||_||_||_||_||_||_||_||_||_||_||_| |___________|| 
 *     |___________________________________________________________|
 *
 *
 *	This is an OFFPAGE slab. These can be larger than UMA_SLAB_SIZE.
 *
 *	___________________________________________________________
 *     | _  _  _  _  _  _  _  _  _  _  _  _  _  _  _  _  _  _  _   |
 *     ||i||i||i||i||i||i||i||i||i||i||i||i||i||i||i||i||i||i||i|  |
 *     ||_||_||_||_||_||_||_||_||_||_||_||_||_||_||_||_||_||_||_|  |
 *     |___________________________________________________________|
 *       ___________    ^
 *	|slab header|   |
 *	|___________|---*
 *
 */

#ifndef VM_UMA_INT_H
#define VM_UMA_INT_H

#include <sys/mutex.h>

#define UMA_SLAB_SIZE	PAGE_SIZE	/* How big are our slabs? */
#define UMA_SLAB_MASK	(PAGE_SIZE - 1)	/* Mask to get back to the page */
#define UMA_SLAB_SHIFT	PAGE_SHIFT	/* Number of bits PAGE_MASK */

#define UMA_BOOT_PAGES		15	/* Number of pages allocated for startup */
#define UMA_WORKING_TIME	20	/* Seconds worth of items to keep */


/* Max waste before going to off page slab management */
#define UMA_MAX_WASTE	(UMA_SLAB_SIZE / 10)

/*
 * I doubt there will be many cases where this is exceeded. This is the initial
 * size of the hash table for uma_slabs that are managed off page. This hash
 * does expand by powers of two.  Currently it doesn't get smaller.
 */
#define UMA_HASH_SIZE_INIT	32		


/* 
 * I should investigate other hashing algorithms.  This should yield a low
 * number of collisions if the pages are relatively contiguous.
 *
 * This is the same algorithm that most processor caches use.
 *
 * I'm shifting and masking instead of % because it should be faster.
 */

#define UMA_HASH(h, s) ((((unsigned long)s) >> UMA_SLAB_SHIFT) &	\
    (h)->uh_hashmask)

#define UMA_HASH_INSERT(h, s, mem)					\
		SLIST_INSERT_HEAD(&(h)->uh_slab_hash[UMA_HASH((h),	\
		    (mem))], (s), us_hlink);
#define UMA_HASH_REMOVE(h, s, mem)					\
		SLIST_REMOVE(&(h)->uh_slab_hash[UMA_HASH((h),		\
		    (mem))], (s), uma_slab, us_hlink);

/* Page management structure */

/* Sorry for the union, but space efficiency is important */
struct uma_slab {
	uma_zone_t	us_zone;		/* Zone we live in */
	union {
		LIST_ENTRY(uma_slab)	us_link;	/* slabs in zone */
		unsigned long	us_size;	/* Size of allocation */
	} us_type;
	SLIST_ENTRY(uma_slab)	us_hlink;	/* Link for hash table */
	u_int8_t	*us_data;		/* First item */
	u_int8_t	us_flags;		/* Page flags see uma.h */
	u_int8_t	us_freecount;	/* How many are free? */
	u_int8_t	us_firstfree;	/* First free item index */
	u_int8_t	us_freelist[1];	/* Free List (actually larger) */
};

#define us_link	us_type.us_link
#define us_size	us_type.us_size

typedef struct uma_slab * uma_slab_t;

/* Hash table for freed address -> slab translation */

SLIST_HEAD(slabhead, uma_slab);

struct uma_hash {
	struct slabhead	*uh_slab_hash;	/* Hash table for slabs */
	int		uh_hashsize;	/* Current size of the hash table */
	int		uh_hashmask;	/* Mask used during hashing */
};

extern struct uma_hash *mallochash;

/*
 * Structures for per cpu queues.
 */

/*
 * This size was chosen so that the struct bucket size is roughly
 * 128 * sizeof(void *).  This is exactly true for x86, and for alpha
 * it will would be 32bits smaller if it didn't have alignment adjustments.
 */

#define UMA_BUCKET_SIZE	125

struct uma_bucket {
	LIST_ENTRY(uma_bucket)	ub_link;	/* Link into the zone */
	int16_t	ub_ptr;				/* Pointer to current item */
	void	*ub_bucket[UMA_BUCKET_SIZE];	/* actual allocation storage */
};

typedef struct uma_bucket * uma_bucket_t;

struct uma_cache {
	struct mtx	uc_lock;	/* Spin lock on this cpu's bucket */
	uma_bucket_t	uc_freebucket;	/* Bucket we're freeing to */
	uma_bucket_t	uc_allocbucket;	/* Bucket to allocate from */
	u_int64_t	uc_allocs;	/* Count of allocations */
};

typedef struct uma_cache * uma_cache_t;

#define LOCKNAME_LEN	16		/* Length of the name for cpu locks */

/*
 * Zone management structure 
 *
 * TODO: Optimize for cache line size
 *
 */
struct uma_zone {
	char		uz_lname[LOCKNAME_LEN];	/* Text name for the cpu lock */
	char		*uz_name;	/* Text name of the zone */
	LIST_ENTRY(uma_zone)	uz_link;	/* List of all zones */
	u_int32_t	uz_align;	/* Alignment mask */
	u_int32_t	uz_pages;	/* Total page count */

/* Used during alloc / free */
	struct mtx	uz_lock;	/* Lock for the zone */
	u_int32_t	uz_free;	/* Count of items free in slabs */
	u_int16_t	uz_ipers;	/* Items per slab */
	u_int16_t	uz_flags;	/* Internal flags */

	LIST_HEAD(,uma_slab)	uz_part_slab;	/* partially allocated slabs */
	LIST_HEAD(,uma_slab)	uz_free_slab;	/* empty slab list */
	LIST_HEAD(,uma_slab)	uz_full_slab;	/* full slabs */
	LIST_HEAD(,uma_bucket)	uz_full_bucket;	/* full buckets */
	LIST_HEAD(,uma_bucket)	uz_free_bucket;	/* Buckets for frees */
	u_int32_t	uz_size;	/* Requested size of each item */
	u_int32_t	uz_rsize;	/* Real size of each item */

	struct uma_hash	uz_hash;
	u_int16_t	uz_pgoff;	/* Offset to uma_slab struct */
	u_int16_t	uz_ppera;	/* pages per allocation from backend */
	u_int16_t	uz_cacheoff;	/* Next cache offset */
	u_int16_t	uz_cachemax;	/* Max cache offset */

	uma_ctor	uz_ctor;	/* Constructor for each allocation */
	uma_dtor	uz_dtor;	/* Destructor */
	u_int64_t	uz_allocs;	/* Total number of allocations */

	uma_init	uz_init;	/* Initializer for each item */
	uma_fini	uz_fini;	/* Discards memory */
	uma_alloc	uz_allocf;	/* Allocation function */
	uma_free	uz_freef;	/* Free routine */
	struct vm_object	*uz_obj;	/* Zone specific object */
	vm_offset_t	uz_kva;		/* Base kva for zones with objs */
	u_int32_t	uz_maxpages;	/* Maximum number of pages to alloc */
	u_int32_t	uz_cachefree;	/* Last count of items free in caches */
	u_int64_t	uz_oallocs;	/* old allocs count */
	u_int64_t	uz_wssize;	/* Working set size */
	int		uz_recurse;	/* Allocation recursion count */
	uint16_t	uz_fills;	/* Outstanding bucket fills */
	uint16_t	uz_count;	/* Highest value ub_ptr can have */
	/*
	 * This HAS to be the last item because we adjust the zone size
	 * based on NCPU and then allocate the space for the zones.
	 */
	struct uma_cache	uz_cpu[1];	/* Per cpu caches */
};

#define UMA_CACHE_INC	16	/* How much will we move data */

#define UMA_ZFLAG_OFFPAGE	0x0001	/* Struct slab/freelist off page */
#define UMA_ZFLAG_PRIVALLOC	0x0002	/* Zone has supplied it's own alloc */
#define UMA_ZFLAG_INTERNAL	0x0004	/* Internal zone, no offpage no PCPU */
#define UMA_ZFLAG_MALLOC	0x0008	/* Zone created by malloc */
#define UMA_ZFLAG_NOFREE	0x0010	/* Don't free data from this zone */
#define UMA_ZFLAG_FULL		0x0020	/* This zone reached uz_maxpages */
#define UMA_ZFLAG_BUCKETCACHE	0x0040	/* Only allocate buckets from cache */

/* This lives in uflags */
#define UMA_ZONE_INTERNAL	0x1000	/* Internal zone for uflags */

/* Internal prototypes */
static __inline uma_slab_t hash_sfind(struct uma_hash *hash, u_int8_t *data);
void *uma_large_malloc(int size, int wait);
void uma_large_free(uma_slab_t slab);

/* Lock Macros */

#define	ZONE_LOCK_INIT(z, lc)					\
	do {							\
		if ((lc))					\
			mtx_init(&(z)->uz_lock, (z)->uz_name,	\
			    (z)->uz_name, MTX_DEF | MTX_DUPOK);	\
		else						\
			mtx_init(&(z)->uz_lock, (z)->uz_name,	\
			    "UMA zone", MTX_DEF | MTX_DUPOK);	\
	} while (0)
	    
#define	ZONE_LOCK_FINI(z)	mtx_destroy(&(z)->uz_lock)
#define	ZONE_LOCK(z)	mtx_lock(&(z)->uz_lock)
#define ZONE_UNLOCK(z)	mtx_unlock(&(z)->uz_lock)

#define	CPU_LOCK_INIT(z, cpu, lc)				\
	do {							\
		if ((lc))					\
			mtx_init(&(z)->uz_cpu[(cpu)].uc_lock,	\
			    (z)->uz_lname, (z)->uz_lname,	\
			    MTX_DEF | MTX_DUPOK);		\
		else						\
			mtx_init(&(z)->uz_cpu[(cpu)].uc_lock,	\
			    (z)->uz_lname, "UMA cpu",		\
			    MTX_DEF | MTX_DUPOK);		\
	} while (0)

#define	CPU_LOCK_FINI(z, cpu)	\
	mtx_destroy(&(z)->uz_cpu[(cpu)].uc_lock)

#define CPU_LOCK(z, cpu)	\
	mtx_lock(&(z)->uz_cpu[(cpu)].uc_lock)

#define CPU_UNLOCK(z, cpu)	\
	mtx_unlock(&(z)->uz_cpu[(cpu)].uc_lock)

/*
 * Find a slab within a hash table.  This is used for OFFPAGE zones to lookup
 * the slab structure.
 *
 * Arguments:
 *	hash  The hash table to search.
 *	data  The base page of the item.
 *
 * Returns:
 *	A pointer to a slab if successful, else NULL.
 */
static __inline uma_slab_t
hash_sfind(struct uma_hash *hash, u_int8_t *data)
{
        uma_slab_t slab;
        int hval;

        hval = UMA_HASH(hash, data);

        SLIST_FOREACH(slab, &hash->uh_slab_hash[hval], us_hlink) {
                if ((u_int8_t *)slab->us_data == data)
                        return (slab);
        }
        return (NULL);
}


#endif /* VM_UMA_INT_H */