The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/vm/uma.h

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    1 /*
    2  * Copyright (c) 2002, Jeffrey Roberson <jeff@freebsd.org>
    3  * All rights reserved.
    4  *
    5  * Redistribution and use in source and binary forms, with or without
    6  * modification, are permitted provided that the following conditions
    7  * are met:
    8  * 1. Redistributions of source code must retain the above copyright
    9  *    notice unmodified, this list of conditions, and the following
   10  *    disclaimer.
   11  * 2. Redistributions in binary form must reproduce the above copyright
   12  *    notice, this list of conditions and the following disclaimer in the
   13  *    documentation and/or other materials provided with the distribution.
   14  *
   15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
   16  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   17  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
   18  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
   19  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
   20  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   21  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   22  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   23  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
   24  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   25  *
   26  * $FreeBSD: releng/5.0/sys/vm/uma.h 105689 2002-10-22 12:10:27Z sheldonh $
   27  *
   28  */
   29 
   30 /*
   31  * uma.h - External definitions for the Universal Memory Allocator
   32  *
   33 */
   34 
   35 #ifndef VM_UMA_H
   36 #define VM_UMA_H
   37 
   38 #include <sys/param.h>          /* For NULL */
   39 #include <sys/malloc.h>         /* For M_* */
   40 
   41 /* User visable parameters */
   42 #define UMA_SMALLEST_UNIT       (PAGE_SIZE / 256) /* Smallest item allocated */
   43 
   44 /* Types and type defs */
   45 
   46 struct uma_zone; 
   47 /* Opaque type used as a handle to the zone */
   48 typedef struct uma_zone * uma_zone_t;
   49 
   50 /* 
   51  * Item constructor
   52  *
   53  * Arguments:
   54  *      item  A pointer to the memory which has been allocated.
   55  *      arg   The arg field passed to uma_zalloc_arg
   56  *      size  The size of the allocated item
   57  * 
   58  * Returns:
   59  *      Nothing
   60  *
   61  * Discussion:
   62  *      The constructor is called just before the memory is returned
   63  *      to the user. It may block if necessary.
   64  */
   65 typedef void (*uma_ctor)(void *mem, int size, void *arg);
   66 
   67 /*
   68  * Item destructor
   69  *
   70  * Arguments:
   71  *      item  A pointer to the memory which has been allocated.
   72  *      size  The size of the item being destructed.
   73  *      arg   Argument passed through uma_zfree_arg
   74  * 
   75  * Returns:
   76  *      Nothing
   77  *
   78  * Discussion:
   79  *      The destructor may perform operations that differ from those performed
   80  *      by the initializer, but it must leave the object in the same state.
   81  *      This IS type stable storage.  This is called after EVERY zfree call.
   82  */
   83 typedef void (*uma_dtor)(void *mem, int size, void *arg);
   84 
   85 /* 
   86  * Item initializer
   87  *
   88  * Arguments:
   89  *      item  A pointer to the memory which has been allocated.
   90  *      size  The size of the item being initialized.
   91  * 
   92  * Returns:
   93  *      Nothing
   94  *
   95  * Discussion:
   96  *      The initializer is called when the memory is cached in the uma zone. 
   97  *      this should be the same state that the destructor leaves the object in.
   98  */
   99 typedef void (*uma_init)(void *mem, int size);
  100 
  101 /*
  102  * Item discard function
  103  *
  104  * Arguments:
  105  *      item  A pointer to memory which has been 'freed' but has not left the 
  106  *            zone's cache.
  107  *      size  The size of the item being discarded.
  108  *
  109  * Returns:
  110  *      Nothing
  111  *
  112  * Discussion:
  113  *      This routine is called when memory leaves a zone and is returned to the
  114  *      system for other uses.  It is the counter part to the init function.
  115  */
  116 typedef void (*uma_fini)(void *mem, int size);
  117 
  118 /*
  119  * What's the difference between initializing and constructing?
  120  *
  121  * The item is initialized when it is cached, and this is the state that the 
  122  * object should be in when returned to the allocator. The purpose of this is
  123  * to remove some code which would otherwise be called on each allocation by
  124  * utilizing a known, stable state.  This differs from the constructor which
  125  * will be called on EVERY allocation.
  126  *
  127  * For example, in the initializer you may want to initialize embeded locks,
  128  * NULL list pointers, set up initial states, magic numbers, etc.  This way if
  129  * the object is held in the allocator and re-used it won't be necessary to
  130  * re-initialize it.
  131  *
  132  * The constructor may be used to lock a data structure, link it on to lists,
  133  * bump reference counts or total counts of outstanding structures, etc.
  134  *
  135  */
  136 
  137 
  138 /* Function proto types */
  139 
  140 /*
  141  * Create a new uma zone
  142  *
  143  * Arguments:
  144  *      name  The text name of the zone for debugging and stats, this memory
  145  *              should not be freed until the zone has been deallocated.
  146  *      size  The size of the object that is being created.
  147  *      ctor  The constructor that is called when the object is allocated
  148  *      dtor  The destructor that is called when the object is freed.
  149  *      init  An initializer that sets up the initial state of the memory.
  150  *      fini  A discard function that undoes initialization done by init.
  151  *              ctor/dtor/init/fini may all be null, see notes above.
  152  *      align A bitmask that corisponds to the requested alignment
  153  *              eg 4 would be 0x3
  154  *      flags A set of parameters that control the behavior of the zone
  155  *
  156  * Returns:
  157  *      A pointer to a structure which is intended to be opaque to users of
  158  *      the interface.  The value may be null if the wait flag is not set.
  159  */
  160 
  161 uma_zone_t uma_zcreate(char *name, size_t size, uma_ctor ctor, uma_dtor dtor,
  162                         uma_init uminit, uma_fini fini, int align,
  163                         u_int16_t flags);
  164 
  165 /* Definitions for uma_zcreate flags */
  166 #define UMA_ZONE_PAGEABLE       0x0001  /* Return items not fully backed by
  167                                            physical memory XXX Not yet */
  168 #define UMA_ZONE_ZINIT          0x0002  /* Initialize with zeros */
  169 #define UMA_ZONE_STATIC         0x0004  /* Staticly sized zone */
  170 #define UMA_ZONE_OFFPAGE        0x0008  /* Force the slab structure allocation
  171                                            off of the real memory */
  172 #define UMA_ZONE_MALLOC         0x0010  /* For use by malloc(9) only! */
  173 #define UMA_ZONE_NOFREE         0x0020  /* Do not free slabs of this type! */
  174 #define UMA_ZONE_MTXCLASS       0x0040  /* Create a new lock class */
  175 #define UMA_ZONE_VM             0x0080  /*
  176                                          * Used for internal vm datastructures
  177                                          * only.
  178                                          */
  179 #define UMA_ZONE_HASH           0x0100  /*
  180                                          * Use a hash table instead of caching
  181                                          * information in the vm_page.
  182                                          */
  183 
  184 /* Definitions for align */
  185 #define UMA_ALIGN_PTR   (sizeof(void *) - 1)    /* Alignment fit for ptr */
  186 #define UMA_ALIGN_LONG  (sizeof(long) - 1)      /* "" long */
  187 #define UMA_ALIGN_INT   (sizeof(int) - 1)       /* "" int */
  188 #define UMA_ALIGN_SHORT (sizeof(short) - 1)     /* "" short */
  189 #define UMA_ALIGN_CHAR  (sizeof(char) - 1)      /* "" char */
  190 #define UMA_ALIGN_CACHE (16 - 1)                /* Cache line size align */
  191 
  192 /*
  193  * Destroys an empty uma zone.  If the zone is not empty uma complains loudly.
  194  *
  195  * Arguments:
  196  *      zone  The zone we want to destroy.
  197  *
  198  */
  199 
  200 void uma_zdestroy(uma_zone_t zone);
  201 
  202 /*
  203  * Allocates an item out of a zone
  204  *
  205  * Arguments:
  206  *      zone  The zone we are allocating from
  207  *      arg   This data is passed to the ctor function
  208  *      flags See sys/malloc.h for available flags.
  209  *
  210  * Returns:
  211  *      A non null pointer to an initialized element from the zone is
  212  *      garanteed if the wait flag is M_WAITOK, otherwise a null pointer may be
  213  *      returned if the zone is empty or the ctor failed.
  214  */
  215 
  216 void *uma_zalloc_arg(uma_zone_t zone, void *arg, int flags);
  217 
  218 /*
  219  * Allocates an item out of a zone without supplying an argument
  220  *
  221  * This is just a wrapper for uma_zalloc_arg for convenience.
  222  *
  223  */
  224 static __inline void *uma_zalloc(uma_zone_t zone, int flags);
  225 
  226 static __inline void *
  227 uma_zalloc(uma_zone_t zone, int flags)
  228 {
  229         return uma_zalloc_arg(zone, NULL, flags);
  230 }
  231 
  232 /*
  233  * Frees an item back into the specified zone.
  234  *
  235  * Arguments:
  236  *      zone  The zone the item was originally allocated out of.
  237  *      item  The memory to be freed.
  238  *      arg   Argument passed to the destructor
  239  *
  240  * Returns:
  241  *      Nothing.
  242  */
  243 
  244 void uma_zfree_arg(uma_zone_t zone, void *item, void *arg);
  245 
  246 /*
  247  * Frees an item back to a zone without supplying an argument
  248  *
  249  * This is just a wrapper for uma_zfree_arg for convenience.
  250  *
  251  */
  252 static __inline void uma_zfree(uma_zone_t zone, void *item);
  253 
  254 static __inline void
  255 uma_zfree(uma_zone_t zone, void *item)
  256 {
  257         uma_zfree_arg(zone, item, NULL);
  258 }
  259 
  260 /*
  261  * XXX The rest of the prototypes in this header are h0h0 magic for the VM.
  262  * If you think you need to use it for a normal zone you're probably incorrect.
  263  */
  264 
  265 /*
  266  * Backend page supplier routines
  267  *
  268  * Arguments:
  269  *      zone  The zone that is requesting pages
  270  *      size  The number of bytes being requested
  271  *      pflag Flags for these memory pages, see below.
  272  *      wait  Indicates our willingness to block.
  273  *
  274  * Returns:
  275  *      A pointer to the alloced memory or NULL on failure.
  276  */
  277 
  278 typedef void *(*uma_alloc)(uma_zone_t zone, int size, u_int8_t *pflag, int wait);
  279 
  280 /*
  281  * Backend page free routines
  282  *
  283  * Arguments:
  284  *      item  A pointer to the previously allocated pages
  285  *      size  The original size of the allocation
  286  *      pflag The flags for the slab.  See UMA_SLAB_* below
  287  *
  288  * Returns:
  289  *      None
  290  */
  291 typedef void (*uma_free)(void *item, int size, u_int8_t pflag);
  292 
  293 
  294 
  295 /*
  296  * Sets up the uma allocator. (Called by vm_mem_init)
  297  *
  298  * Arguments:
  299  *      bootmem  A pointer to memory used to bootstrap the system.
  300  *
  301  * Returns:
  302  *      Nothing
  303  *
  304  * Discussion:
  305  *      This memory is used for zones which allocate things before the
  306  *      backend page supplier can give us pages.  It should be
  307  *      UMA_SLAB_SIZE * UMA_BOOT_PAGES bytes. (see uma_int.h)
  308  *
  309  */
  310 
  311 void uma_startup(void *bootmem);
  312 
  313 /*
  314  * Finishes starting up the allocator.  This should
  315  * be called when kva is ready for normal allocs.
  316  *
  317  * Arguments:
  318  *      None
  319  *
  320  * Returns:
  321  *      Nothing
  322  *
  323  * Discussion:
  324  *      uma_startup2 is called by kmeminit() to enable us of uma for malloc.
  325  */
  326  
  327 void uma_startup2(void);
  328 
  329 /*
  330  * Reclaims unused memory for all zones
  331  *
  332  * Arguments:
  333  *      None
  334  * Returns:
  335  *      None
  336  *
  337  * This should only be called by the page out daemon.
  338  */
  339 
  340 void uma_reclaim(void);
  341 
  342 /*
  343  * Switches the backing object of a zone
  344  *
  345  * Arguments:
  346  *      zone  The zone to update
  347  *      obj   The obj to use for future allocations
  348  *      size  The size of the object to allocate
  349  *
  350  * Returns:
  351  *      0  if kva space can not be allocated
  352  *      1  if successful
  353  *
  354  * Discussion:
  355  *      A NULL object can be used and uma will allocate one for you.  Setting
  356  *      the size will limit the amount of memory allocated to this zone.
  357  *
  358  */
  359 struct vm_object;
  360 int uma_zone_set_obj(uma_zone_t zone, struct vm_object *obj, int size);
  361 
  362 /*
  363  * Sets a high limit on the number of items allowed in a zone
  364  *
  365  * Arguments:
  366  *      zone  The zone to limit
  367  *
  368  * Returns:
  369  *      Nothing
  370  */
  371 void uma_zone_set_max(uma_zone_t zone, int nitems);
  372 
  373 /*
  374  * Replaces the standard page_alloc or obj_alloc functions for this zone
  375  *
  376  * Arguments:
  377  *      zone   The zone whos back end allocator is being changed.
  378  *      allocf A pointer to the allocation function
  379  *
  380  * Returns:
  381  *      Nothing
  382  *
  383  * Discussion:
  384  *      This could be used to implement pageable allocation, or perhaps
  385  *      even DMA allocators if used in conjunction with the OFFPAGE
  386  *      zone flag.
  387  */
  388 
  389 void uma_zone_set_allocf(uma_zone_t zone, uma_alloc allocf);
  390 
  391 /*
  392  * Used for freeing memory provided by the allocf above
  393  *
  394  * Arguments:
  395  *      zone  The zone that intends to use this free routine.
  396  *      freef The page freeing routine.
  397  *
  398  * Returns:
  399  *      Nothing
  400  */
  401 
  402 void uma_zone_set_freef(uma_zone_t zone, uma_free freef);
  403 
  404 /*
  405  * These flags are setable in the allocf and visable in the freef.
  406  */
  407 #define UMA_SLAB_BOOT   0x01            /* Slab alloced from boot pages */
  408 #define UMA_SLAB_KMEM   0x02            /* Slab alloced from kmem_map */
  409 #define UMA_SLAB_PRIV   0x08            /* Slab alloced from priv allocator */
  410 #define UMA_SLAB_OFFP   0x10            /* Slab is managed separately  */
  411 #define UMA_SLAB_MALLOC 0x20            /* Slab is a large malloc slab */
  412 /* 0x40 and 0x80 are available */
  413 
  414 /*
  415  * Used to pre-fill a zone with some number of items
  416  *
  417  * Arguments:
  418  *      zone    The zone to fill
  419  *      itemcnt The number of items to reserve
  420  *
  421  * Returns:
  422  *      Nothing
  423  *
  424  * NOTE: This is blocking and should only be done at startup
  425  */
  426 void uma_prealloc(uma_zone_t zone, int itemcnt);
  427 
  428 
  429 #endif

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