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, 2003, 2004, 2005 Jeffrey Roberson <jeff@FreeBSD.org>
    3  * Copyright (c) 2004, 2005 Bosko Milekic <bmilekic@FreeBSD.org>
    4  * All rights reserved.
    5  *
    6  * Redistribution and use in source and binary forms, with or without
    7  * modification, are permitted provided that the following conditions
    8  * are met:
    9  * 1. Redistributions of source code must retain the above copyright
   10  *    notice unmodified, this list of conditions, and the following
   11  *    disclaimer.
   12  * 2. Redistributions in binary form must reproduce the above copyright
   13  *    notice, this list of conditions and the following disclaimer in the
   14  *    documentation and/or other materials provided with the distribution.
   15  *
   16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
   17  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   18  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
   19  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
   20  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
   21  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   22  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   23  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   24  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
   25  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   26  *
   27  * $FreeBSD$
   28  *
   29  */
   30 
   31 /*
   32  * uma.h - External definitions for the Universal Memory Allocator
   33  *
   34 */
   35 
   36 #ifndef VM_UMA_H
   37 #define VM_UMA_H
   38 
   39 #include <sys/param.h>          /* For NULL */
   40 #include <sys/malloc.h>         /* For M_* */
   41 
   42 /* User visable parameters */
   43 #define UMA_SMALLEST_UNIT       (PAGE_SIZE / 256) /* Smallest item allocated */
   44 
   45 /* Types and type defs */
   46 
   47 struct uma_zone;
   48 /* Opaque type used as a handle to the zone */
   49 typedef struct uma_zone * uma_zone_t;
   50 
   51 void zone_drain(uma_zone_t);
   52 
   53 /* 
   54  * Item constructor
   55  *
   56  * Arguments:
   57  *      item  A pointer to the memory which has been allocated.
   58  *      arg   The arg field passed to uma_zalloc_arg
   59  *      size  The size of the allocated item
   60  *      flags See zalloc flags
   61  * 
   62  * Returns:
   63  *      0      on success
   64  *      errno  on failure
   65  *
   66  * Discussion:
   67  *      The constructor is called just before the memory is returned
   68  *      to the user. It may block if necessary.
   69  */
   70 typedef int (*uma_ctor)(void *mem, int size, void *arg, int flags);
   71 
   72 /*
   73  * Item destructor
   74  *
   75  * Arguments:
   76  *      item  A pointer to the memory which has been allocated.
   77  *      size  The size of the item being destructed.
   78  *      arg   Argument passed through uma_zfree_arg
   79  * 
   80  * Returns:
   81  *      Nothing
   82  *
   83  * Discussion:
   84  *      The destructor may perform operations that differ from those performed
   85  *      by the initializer, but it must leave the object in the same state.
   86  *      This IS type stable storage.  This is called after EVERY zfree call.
   87  */
   88 typedef void (*uma_dtor)(void *mem, int size, void *arg);
   89 
   90 /* 
   91  * Item initializer
   92  *
   93  * Arguments:
   94  *      item  A pointer to the memory which has been allocated.
   95  *      size  The size of the item being initialized.
   96  *      flags See zalloc flags
   97  * 
   98  * Returns:
   99  *      0      on success
  100  *      errno  on failure
  101  *
  102  * Discussion:
  103  *      The initializer is called when the memory is cached in the uma zone. 
  104  *      this should be the same state that the destructor leaves the object in.
  105  */
  106 typedef int (*uma_init)(void *mem, int size, int flags);
  107 
  108 /*
  109  * Item discard function
  110  *
  111  * Arguments:
  112  *      item  A pointer to memory which has been 'freed' but has not left the 
  113  *            zone's cache.
  114  *      size  The size of the item being discarded.
  115  *
  116  * Returns:
  117  *      Nothing
  118  *
  119  * Discussion:
  120  *      This routine is called when memory leaves a zone and is returned to the
  121  *      system for other uses.  It is the counter part to the init function.
  122  */
  123 typedef void (*uma_fini)(void *mem, int size);
  124 
  125 /*
  126  * What's the difference between initializing and constructing?
  127  *
  128  * The item is initialized when it is cached, and this is the state that the 
  129  * object should be in when returned to the allocator. The purpose of this is
  130  * to remove some code which would otherwise be called on each allocation by
  131  * utilizing a known, stable state.  This differs from the constructor which
  132  * will be called on EVERY allocation.
  133  *
  134  * For example, in the initializer you may want to initialize embeded locks,
  135  * NULL list pointers, set up initial states, magic numbers, etc.  This way if
  136  * the object is held in the allocator and re-used it won't be necessary to
  137  * re-initialize it.
  138  *
  139  * The constructor may be used to lock a data structure, link it on to lists,
  140  * bump reference counts or total counts of outstanding structures, etc.
  141  *
  142  */
  143 
  144 
  145 /* Function proto types */
  146 
  147 /*
  148  * Create a new uma zone
  149  *
  150  * Arguments:
  151  *      name  The text name of the zone for debugging and stats, this memory
  152  *              should not be freed until the zone has been deallocated.
  153  *      size  The size of the object that is being created.
  154  *      ctor  The constructor that is called when the object is allocated
  155  *      dtor  The destructor that is called when the object is freed.
  156  *      init  An initializer that sets up the initial state of the memory.
  157  *      fini  A discard function that undoes initialization done by init.
  158  *              ctor/dtor/init/fini may all be null, see notes above.
  159  *      align A bitmask that corisponds to the requested alignment
  160  *              eg 4 would be 0x3
  161  *      flags A set of parameters that control the behavior of the zone
  162  *
  163  * Returns:
  164  *      A pointer to a structure which is intended to be opaque to users of
  165  *      the interface.  The value may be null if the wait flag is not set.
  166  */
  167 uma_zone_t uma_zcreate(char *name, size_t size, uma_ctor ctor, uma_dtor dtor,
  168                         uma_init uminit, uma_fini fini, int align,
  169                         u_int32_t flags);
  170 
  171 /*
  172  * Create a secondary uma zone
  173  *
  174  * Arguments:
  175  *      name  The text name of the zone for debugging and stats, this memory
  176  *              should not be freed until the zone has been deallocated.
  177  *      ctor  The constructor that is called when the object is allocated
  178  *      dtor  The destructor that is called when the object is freed.
  179  *      zinit  An initializer that sets up the initial state of the memory
  180  *              as the object passes from the Keg's slab to the Zone's cache.
  181  *      zfini  A discard function that undoes initialization done by init
  182  *              as the object passes from the Zone's cache to the Keg's slab.
  183  *
  184  *              ctor/dtor/zinit/zfini may all be null, see notes above.
  185  *              Note that the zinit and zfini specified here are NOT
  186  *              exactly the same as the init/fini specified to uma_zcreate()
  187  *              when creating a master zone.  These zinit/zfini are called
  188  *              on the TRANSITION from keg to zone (and vice-versa). Once
  189  *              these are set, the primary zone may alter its init/fini
  190  *              (which are called when the object passes from VM to keg)
  191  *              using uma_zone_set_init/fini()) as well as its own
  192  *              zinit/zfini (unset by default for master zone) with
  193  *              uma_zone_set_zinit/zfini() (note subtle 'z' prefix).
  194  *
  195  *      master  A reference to this zone's Master Zone (Primary Zone),
  196  *              which contains the backing Keg for the Secondary Zone
  197  *              being added.
  198  *
  199  * Returns:
  200  *      A pointer to a structure which is intended to be opaque to users of
  201  *      the interface.  The value may be null if the wait flag is not set.
  202  */
  203 uma_zone_t uma_zsecond_create(char *name, uma_ctor ctor, uma_dtor dtor,
  204                     uma_init zinit, uma_fini zfini, uma_zone_t master);
  205 
  206 /*
  207  * Definitions for uma_zcreate flags
  208  *
  209  * These flags share space with UMA_ZFLAGs in uma_int.h.  Be careful not to
  210  * overlap when adding new features.  0xf0000000 is in use by uma_int.h.
  211  */
  212 #define UMA_ZONE_PAGEABLE       0x0001  /* Return items not fully backed by
  213                                            physical memory XXX Not yet */
  214 #define UMA_ZONE_ZINIT          0x0002  /* Initialize with zeros */
  215 #define UMA_ZONE_STATIC         0x0004  /* Staticly sized zone */
  216 #define UMA_ZONE_OFFPAGE        0x0008  /* Force the slab structure allocation
  217                                            off of the real memory */
  218 #define UMA_ZONE_MALLOC         0x0010  /* For use by malloc(9) only! */
  219 #define UMA_ZONE_NOFREE         0x0020  /* Do not free slabs of this type! */
  220 #define UMA_ZONE_MTXCLASS       0x0040  /* Create a new lock class */
  221 #define UMA_ZONE_VM             0x0080  /*
  222                                          * Used for internal vm datastructures
  223                                          * only.
  224                                          */
  225 #define UMA_ZONE_HASH           0x0100  /*
  226                                          * Use a hash table instead of caching
  227                                          * information in the vm_page.
  228                                          */
  229 #define UMA_ZONE_SECONDARY      0x0200  /* Zone is a Secondary Zone */
  230 #define UMA_ZONE_REFCNT         0x0400  /* Allocate refcnts in slabs */
  231 #define UMA_ZONE_MAXBUCKET      0x0800  /* Use largest buckets */
  232 
  233 /* Definitions for align */
  234 #define UMA_ALIGN_PTR   (sizeof(void *) - 1)    /* Alignment fit for ptr */
  235 #define UMA_ALIGN_LONG  (sizeof(long) - 1)      /* "" long */
  236 #define UMA_ALIGN_INT   (sizeof(int) - 1)       /* "" int */
  237 #define UMA_ALIGN_SHORT (sizeof(short) - 1)     /* "" short */
  238 #define UMA_ALIGN_CHAR  (sizeof(char) - 1)      /* "" char */
  239 #define UMA_ALIGN_CACHE (0 - 1)                 /* Cache line size align */
  240 
  241 /*
  242  * Destroys an empty uma zone.  If the zone is not empty uma complains loudly.
  243  *
  244  * Arguments:
  245  *      zone  The zone we want to destroy.
  246  *
  247  */
  248 void uma_zdestroy(uma_zone_t zone);
  249 
  250 /*
  251  * Allocates an item out of a zone
  252  *
  253  * Arguments:
  254  *      zone  The zone we are allocating from
  255  *      arg   This data is passed to the ctor function
  256  *      flags See sys/malloc.h for available flags.
  257  *
  258  * Returns:
  259  *      A non null pointer to an initialized element from the zone is
  260  *      garanteed if the wait flag is M_WAITOK, otherwise a null pointer may be
  261  *      returned if the zone is empty or the ctor failed.
  262  */
  263 
  264 void *uma_zalloc_arg(uma_zone_t zone, void *arg, int flags);
  265 
  266 /*
  267  * Allocates an item out of a zone without supplying an argument
  268  *
  269  * This is just a wrapper for uma_zalloc_arg for convenience.
  270  *
  271  */
  272 static __inline void *uma_zalloc(uma_zone_t zone, int flags);
  273 
  274 static __inline void *
  275 uma_zalloc(uma_zone_t zone, int flags)
  276 {
  277         return uma_zalloc_arg(zone, NULL, flags);
  278 }
  279 
  280 /*
  281  * Frees an item back into the specified zone.
  282  *
  283  * Arguments:
  284  *      zone  The zone the item was originally allocated out of.
  285  *      item  The memory to be freed.
  286  *      arg   Argument passed to the destructor
  287  *
  288  * Returns:
  289  *      Nothing.
  290  */
  291 
  292 void uma_zfree_arg(uma_zone_t zone, void *item, void *arg);
  293 
  294 /*
  295  * Frees an item back to a zone without supplying an argument
  296  *
  297  * This is just a wrapper for uma_zfree_arg for convenience.
  298  *
  299  */
  300 static __inline void uma_zfree(uma_zone_t zone, void *item);
  301 
  302 static __inline void
  303 uma_zfree(uma_zone_t zone, void *item)
  304 {
  305         uma_zfree_arg(zone, item, NULL);
  306 }
  307 
  308 /*
  309  * XXX The rest of the prototypes in this header are h0h0 magic for the VM.
  310  * If you think you need to use it for a normal zone you're probably incorrect.
  311  */
  312 
  313 /*
  314  * Backend page supplier routines
  315  *
  316  * Arguments:
  317  *      zone  The zone that is requesting pages
  318  *      size  The number of bytes being requested
  319  *      pflag Flags for these memory pages, see below.
  320  *      wait  Indicates our willingness to block.
  321  *
  322  * Returns:
  323  *      A pointer to the alloced memory or NULL on failure.
  324  */
  325 
  326 typedef void *(*uma_alloc)(uma_zone_t zone, int size, u_int8_t *pflag, int wait);
  327 
  328 /*
  329  * Backend page free routines
  330  *
  331  * Arguments:
  332  *      item  A pointer to the previously allocated pages
  333  *      size  The original size of the allocation
  334  *      pflag The flags for the slab.  See UMA_SLAB_* below
  335  *
  336  * Returns:
  337  *      None
  338  */
  339 typedef void (*uma_free)(void *item, int size, u_int8_t pflag);
  340 
  341 
  342 
  343 /*
  344  * Sets up the uma allocator. (Called by vm_mem_init)
  345  *
  346  * Arguments:
  347  *      bootmem  A pointer to memory used to bootstrap the system.
  348  *
  349  * Returns:
  350  *      Nothing
  351  *
  352  * Discussion:
  353  *      This memory is used for zones which allocate things before the
  354  *      backend page supplier can give us pages.  It should be
  355  *      UMA_SLAB_SIZE * boot_pages bytes. (see uma_int.h)
  356  *
  357  */
  358 
  359 void uma_startup(void *bootmem, int boot_pages);
  360 
  361 /*
  362  * Finishes starting up the allocator.  This should
  363  * be called when kva is ready for normal allocs.
  364  *
  365  * Arguments:
  366  *      None
  367  *
  368  * Returns:
  369  *      Nothing
  370  *
  371  * Discussion:
  372  *      uma_startup2 is called by kmeminit() to enable us of uma for malloc.
  373  */
  374  
  375 void uma_startup2(void);
  376 
  377 /*
  378  * Reclaims unused memory for all zones
  379  *
  380  * Arguments:
  381  *      None
  382  * Returns:
  383  *      None
  384  *
  385  * This should only be called by the page out daemon.
  386  */
  387 
  388 void uma_reclaim(void);
  389 
  390 /*
  391  * Sets the alignment mask to be used for all zones requesting cache
  392  * alignment.  Should be called by MD boot code prior to starting VM/UMA.
  393  *
  394  * Arguments:
  395  *      align The alignment mask
  396  *
  397  * Returns:
  398  *      Nothing
  399  */
  400 void uma_set_align(int align);
  401 
  402 /*
  403  * Switches the backing object of a zone
  404  *
  405  * Arguments:
  406  *      zone  The zone to update
  407  *      obj   The obj to use for future allocations
  408  *      size  The size of the object to allocate
  409  *
  410  * Returns:
  411  *      0  if kva space can not be allocated
  412  *      1  if successful
  413  *
  414  * Discussion:
  415  *      A NULL object can be used and uma will allocate one for you.  Setting
  416  *      the size will limit the amount of memory allocated to this zone.
  417  *
  418  */
  419 struct vm_object;
  420 int uma_zone_set_obj(uma_zone_t zone, struct vm_object *obj, int size);
  421 
  422 /*
  423  * Sets a high limit on the number of items allowed in a zone
  424  *
  425  * Arguments:
  426  *      zone  The zone to limit
  427  *
  428  * Returns:
  429  *      Nothing
  430  */
  431 void uma_zone_set_max(uma_zone_t zone, int nitems);
  432 
  433 /*
  434  * The following two routines (uma_zone_set_init/fini)
  435  * are used to set the backend init/fini pair which acts on an
  436  * object as it becomes allocated and is placed in a slab within
  437  * the specified zone's backing keg.  These should probably not
  438  * be changed once allocations have already begun and only
  439  * immediately upon zone creation.
  440  */
  441 void uma_zone_set_init(uma_zone_t zone, uma_init uminit);
  442 void uma_zone_set_fini(uma_zone_t zone, uma_fini fini);
  443 
  444 /*
  445  * The following two routines (uma_zone_set_zinit/zfini) are
  446  * used to set the zinit/zfini pair which acts on an object as
  447  * it passes from the backing Keg's slab cache to the
  448  * specified Zone's bucket cache.  These should probably not
  449  * be changed once allocations have already begun and
  450  * only immediately upon zone creation.
  451  */
  452 void uma_zone_set_zinit(uma_zone_t zone, uma_init zinit);
  453 void uma_zone_set_zfini(uma_zone_t zone, uma_fini zfini);
  454 
  455 /*
  456  * Replaces the standard page_alloc or obj_alloc functions for this zone
  457  *
  458  * Arguments:
  459  *      zone   The zone whos back end allocator is being changed.
  460  *      allocf A pointer to the allocation function
  461  *
  462  * Returns:
  463  *      Nothing
  464  *
  465  * Discussion:
  466  *      This could be used to implement pageable allocation, or perhaps
  467  *      even DMA allocators if used in conjunction with the OFFPAGE
  468  *      zone flag.
  469  */
  470 
  471 void uma_zone_set_allocf(uma_zone_t zone, uma_alloc allocf);
  472 
  473 /*
  474  * Used for freeing memory provided by the allocf above
  475  *
  476  * Arguments:
  477  *      zone  The zone that intends to use this free routine.
  478  *      freef The page freeing routine.
  479  *
  480  * Returns:
  481  *      Nothing
  482  */
  483 
  484 void uma_zone_set_freef(uma_zone_t zone, uma_free freef);
  485 
  486 /*
  487  * These flags are setable in the allocf and visable in the freef.
  488  */
  489 #define UMA_SLAB_BOOT   0x01            /* Slab alloced from boot pages */
  490 #define UMA_SLAB_KMEM   0x02            /* Slab alloced from kmem_map */
  491 #define UMA_SLAB_PRIV   0x08            /* Slab alloced from priv allocator */
  492 #define UMA_SLAB_OFFP   0x10            /* Slab is managed separately  */
  493 #define UMA_SLAB_MALLOC 0x20            /* Slab is a large malloc slab */
  494 /* 0x40 and 0x80 are available */
  495 
  496 /*
  497  * Used to pre-fill a zone with some number of items
  498  *
  499  * Arguments:
  500  *      zone    The zone to fill
  501  *      itemcnt The number of items to reserve
  502  *
  503  * Returns:
  504  *      Nothing
  505  *
  506  * NOTE: This is blocking and should only be done at startup
  507  */
  508 void uma_prealloc(uma_zone_t zone, int itemcnt);
  509 
  510 /*
  511  * Used to lookup the reference counter allocated for an item
  512  * from a UMA_ZONE_REFCNT zone.  For UMA_ZONE_REFCNT zones,
  513  * reference counters are allocated for items and stored in
  514  * the underlying slab header.
  515  *
  516  * Arguments:
  517  *      zone  The UMA_ZONE_REFCNT zone to which the item belongs.
  518  *      item  The address of the item for which we want a refcnt.
  519  *
  520  * Returns:
  521  *      A pointer to a u_int32_t reference counter.
  522  */
  523 u_int32_t *uma_find_refcnt(uma_zone_t zone, void *item);
  524 
  525 /*
  526  * Used to determine if a fixed-size zone is exhausted.
  527  *
  528  * Arguments:
  529  *      zone    The zone to check
  530  *
  531  * Returns:
  532  *      Non-zero if zone is exhausted.
  533  */
  534 int uma_zone_exhausted(uma_zone_t zone);
  535 int uma_zone_exhausted_nolock(uma_zone_t zone);
  536 
  537 /*
  538  * Exported statistics structures to be used by user space monitoring tools.
  539  * Statistics stream consusts of a uma_stream_header, followed by a series of
  540  * alternative uma_type_header and uma_type_stat structures.  Statistics
  541  * structures
  542  */
  543 #define UMA_STREAM_VERSION      0x00000001
  544 struct uma_stream_header {
  545         u_int32_t       ush_version;    /* Stream format version. */
  546         u_int32_t       ush_maxcpus;    /* Value of MAXCPU for stream. */
  547         u_int32_t       ush_count;      /* Number of records. */
  548         u_int32_t       _ush_pad;       /* Pad/reserved field. */
  549 };
  550 
  551 #define UTH_MAX_NAME    32
  552 #define UTH_ZONE_SECONDARY      0x00000001
  553 struct uma_type_header {
  554         /*
  555          * Static per-zone data, some extracted from the supporting keg.
  556          */
  557         char            uth_name[UTH_MAX_NAME];
  558         u_int32_t       uth_align;      /* Keg: alignment. */
  559         u_int32_t       uth_size;       /* Keg: requested size of item. */
  560         u_int32_t       uth_rsize;      /* Keg: real size of item. */
  561         u_int32_t       uth_maxpages;   /* Keg: maximum number of pages. */
  562         u_int32_t       uth_limit;      /* Keg: max items to allocate. */
  563 
  564         /*
  565          * Current dynamic zone/keg-derived statistics.
  566          */
  567         u_int32_t       uth_pages;      /* Keg: pages allocated. */
  568         u_int32_t       uth_keg_free;   /* Keg: items free. */
  569         u_int32_t       uth_zone_free;  /* Zone: items free. */
  570         u_int32_t       uth_bucketsize; /* Zone: desired bucket size. */
  571         u_int32_t       uth_zone_flags; /* Zone: flags. */
  572         u_int64_t       uth_allocs;     /* Zone: number of allocations. */
  573         u_int64_t       uth_frees;      /* Zone: number of frees. */
  574         u_int64_t       uth_fails;      /* Zone: number of alloc failures. */
  575         u_int64_t       _uth_reserved1[3];      /* Reserved. */
  576 };
  577 
  578 struct uma_percpu_stat {
  579         u_int64_t       ups_allocs;     /* Cache: number of alloctions. */
  580         u_int64_t       ups_frees;      /* Cache: number of frees. */
  581         u_int64_t       ups_cache_free; /* Cache: free items in cache. */
  582         u_int64_t       _ups_reserved[5];       /* Reserved. */
  583 };
  584 
  585 #endif

Cache object: 8741b6a7888d6094d93d3f792b2bb084


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