FreeBSD/Linux Kernel Cross Reference
sys/vm/uma.h

     /*
      * Copyright (c) 2002, Jeffrey Roberson <jeff@freebsd.org>
      * 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: releng/5.3/sys/vm/uma.h 132987 2004-08-02 00:18:36Z green $
     *
     */
    
    /*
     * uma.h - External definitions for the Universal Memory Allocator
     *
    */
    
    #ifndef VM_UMA_H
    #define VM_UMA_H
    
    #include <sys/param.h>          /* For NULL */
    #include <sys/malloc.h>         /* For M_* */
    
    /* User visable parameters */
    #define UMA_SMALLEST_UNIT       (PAGE_SIZE / 256) /* Smallest item allocated */
    
    /* Types and type defs */
    
    struct uma_zone;
    /* Opaque type used as a handle to the zone */
    typedef struct uma_zone * uma_zone_t;
    
    /* 
     * Item constructor
     *
     * Arguments:
     *      item  A pointer to the memory which has been allocated.
     *      arg   The arg field passed to uma_zalloc_arg
     *      size  The size of the allocated item
     *      flags See zalloc flags
     * 
     * Returns:
     *      0      on success
     *      errno  on failure
     *
     * Discussion:
     *      The constructor is called just before the memory is returned
     *      to the user. It may block if necessary.
     */
    typedef int (*uma_ctor)(void *mem, int size, void *arg, int flags);
    
    /*
     * Item destructor
     *
     * Arguments:
     *      item  A pointer to the memory which has been allocated.
     *      size  The size of the item being destructed.
     *      arg   Argument passed through uma_zfree_arg
     * 
     * Returns:
     *      Nothing
     *
     * Discussion:
     *      The destructor may perform operations that differ from those performed
     *      by the initializer, but it must leave the object in the same state.
     *      This IS type stable storage.  This is called after EVERY zfree call.
     */
    typedef void (*uma_dtor)(void *mem, int size, void *arg);
    
    /* 
     * Item initializer
     *
     * Arguments:
     *      item  A pointer to the memory which has been allocated.
     *      size  The size of the item being initialized.
     *      flags See zalloc flags
     * 
     * Returns:
     *      0      on success
     *      errno  on failure
     *
     * Discussion:
    *      The initializer is called when the memory is cached in the uma zone. 
    *      this should be the same state that the destructor leaves the object in.
    */
   typedef int (*uma_init)(void *mem, int size, int flags);
   
   /*
    * Item discard function
    *
    * Arguments:
    *      item  A pointer to memory which has been 'freed' but has not left the 
    *            zone's cache.
    *      size  The size of the item being discarded.
    *
    * Returns:
    *      Nothing
    *
    * Discussion:
    *      This routine is called when memory leaves a zone and is returned to the
    *      system for other uses.  It is the counter part to the init function.
    */
   typedef void (*uma_fini)(void *mem, int size);
   
   /*
    * What's the difference between initializing and constructing?
    *
    * The item is initialized when it is cached, and this is the state that the 
    * object should be in when returned to the allocator. The purpose of this is
    * to remove some code which would otherwise be called on each allocation by
    * utilizing a known, stable state.  This differs from the constructor which
    * will be called on EVERY allocation.
    *
    * For example, in the initializer you may want to initialize embeded locks,
    * NULL list pointers, set up initial states, magic numbers, etc.  This way if
    * the object is held in the allocator and re-used it won't be necessary to
    * re-initialize it.
    *
    * The constructor may be used to lock a data structure, link it on to lists,
    * bump reference counts or total counts of outstanding structures, etc.
    *
    */
   
   
   /* Function proto types */
   
   /*
    * Create a new uma zone
    *
    * Arguments:
    *      name  The text name of the zone for debugging and stats, this memory
    *              should not be freed until the zone has been deallocated.
    *      size  The size of the object that is being created.
    *      ctor  The constructor that is called when the object is allocated
    *      dtor  The destructor that is called when the object is freed.
    *      init  An initializer that sets up the initial state of the memory.
    *      fini  A discard function that undoes initialization done by init.
    *              ctor/dtor/init/fini may all be null, see notes above.
    *      align A bitmask that corisponds to the requested alignment
    *              eg 4 would be 0x3
    *      flags A set of parameters that control the behavior of the zone
    *
    * Returns:
    *      A pointer to a structure which is intended to be opaque to users of
    *      the interface.  The value may be null if the wait flag is not set.
    */
   uma_zone_t uma_zcreate(char *name, size_t size, uma_ctor ctor, uma_dtor dtor,
                           uma_init uminit, uma_fini fini, int align,
                           u_int16_t flags);
   
   /*
    * Create a secondary uma zone
    *
    * Arguments:
    *      name  The text name of the zone for debugging and stats, this memory
    *              should not be freed until the zone has been deallocated.
    *      ctor  The constructor that is called when the object is allocated
    *      dtor  The destructor that is called when the object is freed.
    *      zinit  An initializer that sets up the initial state of the memory
    *              as the object passes from the Keg's slab to the Zone's cache.
    *      zfini  A discard function that undoes initialization done by init
    *              as the object passes from the Zone's cache to the Keg's slab.
    *
    *              ctor/dtor/zinit/zfini may all be null, see notes above.
    *              Note that the zinit and zfini specified here are NOT
    *              exactly the same as the init/fini specified to uma_zcreate()
    *              when creating a master zone.  These zinit/zfini are called
    *              on the TRANSITION from keg to zone (and vice-versa). Once
    *              these are set, the primary zone may alter its init/fini
    *              (which are called when the object passes from VM to keg)
    *              using uma_zone_set_init/fini()) as well as its own
    *              zinit/zfini (unset by default for master zone) with
    *              uma_zone_set_zinit/zfini() (note subtle 'z' prefix).
    *
    *      master  A reference to this zone's Master Zone (Primary Zone),
    *              which contains the backing Keg for the Secondary Zone
    *              being added.
    *
    * Returns:
    *      A pointer to a structure which is intended to be opaque to users of
    *      the interface.  The value may be null if the wait flag is not set.
    */
   uma_zone_t uma_zsecond_create(char *name, uma_ctor ctor, uma_dtor dtor,
                       uma_init zinit, uma_fini zfini, uma_zone_t master);
   
   /*
    * Definitions for uma_zcreate flags
    *
    * These flags share space with UMA_ZFLAGs in uma_int.h.  Be careful not to
    * overlap when adding new features.  0xf000 is in use by uma_int.h.
    */
   #define UMA_ZONE_PAGEABLE       0x0001  /* Return items not fully backed by
                                              physical memory XXX Not yet */
   #define UMA_ZONE_ZINIT          0x0002  /* Initialize with zeros */
   #define UMA_ZONE_STATIC         0x0004  /* Staticly sized zone */
   #define UMA_ZONE_OFFPAGE        0x0008  /* Force the slab structure allocation
                                              off of the real memory */
   #define UMA_ZONE_MALLOC         0x0010  /* For use by malloc(9) only! */
   #define UMA_ZONE_NOFREE         0x0020  /* Do not free slabs of this type! */
   #define UMA_ZONE_MTXCLASS       0x0040  /* Create a new lock class */
   #define UMA_ZONE_VM             0x0080  /*
                                            * Used for internal vm datastructures
                                            * only.
                                            */
   #define UMA_ZONE_HASH           0x0100  /*
                                            * Use a hash table instead of caching
                                            * information in the vm_page.
                                            */
   #define UMA_ZONE_SECONDARY      0x0200  /* Zone is a Secondary Zone */
   #define UMA_ZONE_REFCNT         0x0400  /* Allocate refcnts in slabs */
   #define UMA_ZONE_MAXBUCKET      0x0800  /* Use largest buckets */
   
   /* Definitions for align */
   #define UMA_ALIGN_PTR   (sizeof(void *) - 1)    /* Alignment fit for ptr */
   #define UMA_ALIGN_LONG  (sizeof(long) - 1)      /* "" long */
   #define UMA_ALIGN_INT   (sizeof(int) - 1)       /* "" int */
   #define UMA_ALIGN_SHORT (sizeof(short) - 1)     /* "" short */
   #define UMA_ALIGN_CHAR  (sizeof(char) - 1)      /* "" char */
   #define UMA_ALIGN_CACHE (16 - 1)                /* Cache line size align */
   
   /*
    * Destroys an empty uma zone.  If the zone is not empty uma complains loudly.
    *
    * Arguments:
    *      zone  The zone we want to destroy.
    *
    */
   void uma_zdestroy(uma_zone_t zone);
   
   /*
    * Allocates an item out of a zone
    *
    * Arguments:
    *      zone  The zone we are allocating from
    *      arg   This data is passed to the ctor function
    *      flags See sys/malloc.h for available flags.
    *
    * Returns:
    *      A non null pointer to an initialized element from the zone is
    *      garanteed if the wait flag is M_WAITOK, otherwise a null pointer may be
    *      returned if the zone is empty or the ctor failed.
    */
   
   void *uma_zalloc_arg(uma_zone_t zone, void *arg, int flags);
   
   /*
    * Allocates an item out of a zone without supplying an argument
    *
    * This is just a wrapper for uma_zalloc_arg for convenience.
    *
    */
   static __inline void *uma_zalloc(uma_zone_t zone, int flags);
   
   static __inline void *
   uma_zalloc(uma_zone_t zone, int flags)
   {
           return uma_zalloc_arg(zone, NULL, flags);
   }
   
   /*
    * Frees an item back into the specified zone.
    *
    * Arguments:
    *      zone  The zone the item was originally allocated out of.
    *      item  The memory to be freed.
    *      arg   Argument passed to the destructor
    *
    * Returns:
    *      Nothing.
    */
   
   void uma_zfree_arg(uma_zone_t zone, void *item, void *arg);
   
   /*
    * Frees an item back to a zone without supplying an argument
    *
    * This is just a wrapper for uma_zfree_arg for convenience.
    *
    */
   static __inline void uma_zfree(uma_zone_t zone, void *item);
   
   static __inline void
   uma_zfree(uma_zone_t zone, void *item)
   {
           uma_zfree_arg(zone, item, NULL);
   }
   
   /*
    * XXX The rest of the prototypes in this header are h0h0 magic for the VM.
    * If you think you need to use it for a normal zone you're probably incorrect.
    */
   
   /*
    * Backend page supplier routines
    *
    * Arguments:
    *      zone  The zone that is requesting pages
    *      size  The number of bytes being requested
    *      pflag Flags for these memory pages, see below.
    *      wait  Indicates our willingness to block.
    *
    * Returns:
    *      A pointer to the alloced memory or NULL on failure.
    */
   
   typedef void *(*uma_alloc)(uma_zone_t zone, int size, u_int8_t *pflag, int wait);
   
   /*
    * Backend page free routines
    *
    * Arguments:
    *      item  A pointer to the previously allocated pages
    *      size  The original size of the allocation
    *      pflag The flags for the slab.  See UMA_SLAB_* below
    *
    * Returns:
    *      None
    */
   typedef void (*uma_free)(void *item, int size, u_int8_t pflag);
   
   
   
   /*
    * Sets up the uma allocator. (Called by vm_mem_init)
    *
    * Arguments:
    *      bootmem  A pointer to memory used to bootstrap the system.
    *
    * Returns:
    *      Nothing
    *
    * Discussion:
    *      This memory is used for zones which allocate things before the
    *      backend page supplier can give us pages.  It should be
    *      UMA_SLAB_SIZE * UMA_BOOT_PAGES bytes. (see uma_int.h)
    *
    */
   
   void uma_startup(void *bootmem);
   
   /*
    * Finishes starting up the allocator.  This should
    * be called when kva is ready for normal allocs.
    *
    * Arguments:
    *      None
    *
    * Returns:
    *      Nothing
    *
    * Discussion:
    *      uma_startup2 is called by kmeminit() to enable us of uma for malloc.
    */
    
   void uma_startup2(void);
   
   /*
    * Reclaims unused memory for all zones
    *
    * Arguments:
    *      None
    * Returns:
    *      None
    *
    * This should only be called by the page out daemon.
    */
   
   void uma_reclaim(void);
   
   /*
    * Switches the backing object of a zone
    *
    * Arguments:
    *      zone  The zone to update
    *      obj   The obj to use for future allocations
    *      size  The size of the object to allocate
    *
    * Returns:
    *      0  if kva space can not be allocated
    *      1  if successful
    *
    * Discussion:
    *      A NULL object can be used and uma will allocate one for you.  Setting
    *      the size will limit the amount of memory allocated to this zone.
    *
    */
   struct vm_object;
   int uma_zone_set_obj(uma_zone_t zone, struct vm_object *obj, int size);
   
   /*
    * Sets a high limit on the number of items allowed in a zone
    *
    * Arguments:
    *      zone  The zone to limit
    *
    * Returns:
    *      Nothing
    */
   void uma_zone_set_max(uma_zone_t zone, int nitems);
   
   /*
    * The following two routines (uma_zone_set_init/fini)
    * are used to set the backend init/fini pair which acts on an
    * object as it becomes allocated and is placed in a slab within
    * the specified zone's backing keg.  These should probably not
    * be changed once allocations have already begun and only
    * immediately upon zone creation.
    */
   void uma_zone_set_init(uma_zone_t zone, uma_init uminit);
   void uma_zone_set_fini(uma_zone_t zone, uma_fini fini);
   
   /*
    * The following two routines (uma_zone_set_zinit/zfini) are
    * used to set the zinit/zfini pair which acts on an object as
    * it passes from the backing Keg's slab cache to the
    * specified Zone's bucket cache.  These should probably not
    * be changed once allocations have already begun and
    * only immediately upon zone creation.
    */
   void uma_zone_set_zinit(uma_zone_t zone, uma_init zinit);
   void uma_zone_set_zfini(uma_zone_t zone, uma_fini zfini);
   
   /*
    * Replaces the standard page_alloc or obj_alloc functions for this zone
    *
    * Arguments:
    *      zone   The zone whos back end allocator is being changed.
    *      allocf A pointer to the allocation function
    *
    * Returns:
    *      Nothing
    *
    * Discussion:
    *      This could be used to implement pageable allocation, or perhaps
    *      even DMA allocators if used in conjunction with the OFFPAGE
    *      zone flag.
    */
   
   void uma_zone_set_allocf(uma_zone_t zone, uma_alloc allocf);
   
   /*
    * Used for freeing memory provided by the allocf above
    *
    * Arguments:
    *      zone  The zone that intends to use this free routine.
    *      freef The page freeing routine.
    *
    * Returns:
    *      Nothing
    */
   
   void uma_zone_set_freef(uma_zone_t zone, uma_free freef);
   
   /*
    * These flags are setable in the allocf and visable in the freef.
    */
   #define UMA_SLAB_BOOT   0x01            /* Slab alloced from boot pages */
   #define UMA_SLAB_KMEM   0x02            /* Slab alloced from kmem_map */
   #define UMA_SLAB_PRIV   0x08            /* Slab alloced from priv allocator */
   #define UMA_SLAB_OFFP   0x10            /* Slab is managed separately  */
   #define UMA_SLAB_MALLOC 0x20            /* Slab is a large malloc slab */
   /* 0x40 and 0x80 are available */
   
   /*
    * Used to pre-fill a zone with some number of items
    *
    * Arguments:
    *      zone    The zone to fill
    *      itemcnt The number of items to reserve
    *
    * Returns:
    *      Nothing
    *
    * NOTE: This is blocking and should only be done at startup
    */
   void uma_prealloc(uma_zone_t zone, int itemcnt);
   
   /*
    * Used to lookup the reference counter allocated for an item
    * from a UMA_ZONE_REFCNT zone.  For UMA_ZONE_REFCNT zones,
    * reference counters are allocated for items and stored in
    * the underlying slab header.
    *
    * Arguments:
    *      zone  The UMA_ZONE_REFCNT zone to which the item belongs.
    *      item  The address of the item for which we want a refcnt.
    *
    * Returns:
    *      A pointer to a u_int32_t reference counter.
    */
   u_int32_t *uma_find_refcnt(uma_zone_t zone, void *item);
   
   #endif

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