1 /* Declarations for `mmalloc' and friends.
2 Copyright 1990, 1991, 1992 Free Software Foundation
4 Written May 1989 by Mike Haertel.
5 Heavily modified Mar 1992 by Fred Fish. (fnf@cygnus.com) */
7 /* Copyright (c) 2010. The SimGrid Team.
8 * All rights reserved. */
10 /* This program is free software; you can redistribute it and/or modify it
11 * under the terms of the license (GNU LGPL) which comes with this package. */
14 #define __MMPRIVATE_H 1
17 #include "xbt/xbt_os_thread.h"
18 #include "xbt/mmalloc.h"
20 #include "xbt/dynar.h"
21 #include <semaphore.h>
32 #define MMALLOC_MAGIC "mmalloc" /* Mapped file magic number */
33 #define MMALLOC_MAGIC_SIZE 8 /* Size of magic number buf */
34 #define MMALLOC_VERSION 2 /* Current mmalloc version */
36 /* The allocator divides the heap into blocks of fixed size; large
37 requests receive one or more whole blocks, and small requests
38 receive a fragment of a block. Fragment sizes are powers of two,
39 and all fragments of a block are the same size. When all the
40 fragments in a block have been freed, the block itself is freed.
42 FIXME: we are not targeting 16bits machines anymore; update values */
44 #define INT_BIT (CHAR_BIT * sizeof(int))
45 #define BLOCKLOG (INT_BIT > 16 ? 12 : 9)
46 #define BLOCKSIZE ((unsigned int) 1 << BLOCKLOG)
47 #define BLOCKIFY(SIZE) (((SIZE) + BLOCKSIZE - 1) / BLOCKSIZE)
49 /* We keep fragment-specific meta-data for introspection purposes, and these
50 * information are kept in fixed lenght arrays. Here is the computation of
53 * Never make SMALLEST_POSSIBLE_MALLOC smaller than sizeof(list) because we
54 * need to enlist the free fragments.
57 //#define SMALLEST_POSSIBLE_MALLOC (sizeof(struct list))
58 #define SMALLEST_POSSIBLE_MALLOC (16*sizeof(struct list))
59 #define MAX_FRAGMENT_PER_BLOCK (BLOCKSIZE / SMALLEST_POSSIBLE_MALLOC)
61 /* The difference between two pointers is a signed int. On machines where
62 the data addresses have the high bit set, we need to ensure that the
63 difference becomes an unsigned int when we are using the address as an
64 integral value. In addition, when using with the '%' operator, the
65 sign of the result is machine dependent for negative values, so force
66 it to be treated as an unsigned int. */
68 #define ADDR2UINT(addr) ((uintptr_t) ((char*) (addr) - (char*) NULL))
69 #define RESIDUAL(addr,bsize) ((uintptr_t) (ADDR2UINT (addr) % (bsize)))
71 /* Determine the amount of memory spanned by the initial heap table
72 (not an absolute limit). */
74 #define HEAP (INT_BIT > 16 ? 4194304 : 65536)
76 /* Number of contiguous free blocks allowed to build up at the end of
77 memory before they will be returned to the system.
78 FIXME: this is not used anymore: we never return memory to the system. */
79 #define FINAL_FREE_BLOCKS 8
81 /* Where to start searching the free list when looking for new memory.
82 The two possible values are 0 and heapindex. Starting at 0 seems
83 to reduce total memory usage, while starting at heapindex seems to
86 #define MALLOC_SEARCH_START mdp -> heapindex
88 /* Address to block number and vice versa. */
90 #define BLOCK(A) (((char*) (A) - (char*) mdp -> heapbase) / BLOCKSIZE + 1)
92 #define ADDRESS(B) ((void*) (((ADDR2UINT(B)) - 1) * BLOCKSIZE + (char*) mdp -> heapbase))
94 /* Doubly linked lists of free fragments. */
100 /* Statistics available to the user. */
103 size_t bytes_total; /* Total size of the heap. */
104 size_t chunks_used; /* Chunks allocated by the user. */
105 size_t bytes_used; /* Byte total of user-allocated chunks. */
106 size_t chunks_free; /* Chunks in the free list. */
107 size_t bytes_free; /* Byte total of chunks in the free list. */
110 /* Data structure giving per-block information.
112 * There is one such structure in the mdp->heapinfo array per block used in that heap,
113 * the array index is the block number.
115 * There is several types of blocks in memory:
116 * - full busy blocks: used when we are asked to malloc a block which size is > BLOCKSIZE/2
117 * In this situation, the full block is given to the malloc.
119 * - fragmented busy blocks: when asked for smaller amount of memory.
120 * Fragment sizes are only power of 2. When looking for such a free fragment,
121 * we get one from mdp->fraghead (that contains a linked list of blocks fragmented at that
122 * size and containing a free fragment), or we get a fresh block that we fragment.
124 * - free blocks are grouped by clusters, that are chained together.
125 * When looking for free blocks, we traverse the mdp->heapinfo looking
126 * for a cluster of free blocks that would be large enough.
128 * The size of the cluster is only to be trusted in the first block of the cluster, not in the middle blocks.
130 * The type field is consistently updated for every blocks, even within clusters of blocks.
131 * You can crawl the array and rely on that value.
135 int type; /* 0: busy large block
136 >0: busy fragmented (fragments of size 2^type bytes)
140 /* Heap information for a busy block. */
142 size_t nfree; /* Free fragments in a fragmented block. */
143 size_t first; /* First free fragment of the block. */
144 unsigned short frag_size[MAX_FRAGMENT_PER_BLOCK];
145 void *bt[MAX_FRAGMENT_PER_BLOCK][XBT_BACKTRACE_SIZE]; /* Where it was malloced (or realloced lastly) */
146 int equal_to[MAX_FRAGMENT_PER_BLOCK];
149 size_t size; /* Size (in blocks) of a large cluster. */
150 size_t busy_size; /* Actually used space, in bytes */
151 void *bt[XBT_BACKTRACE_SIZE]; /* Where it was malloced (or realloced lastly) */
155 /* Heap information for a free block (that may be the first of a free cluster). */
157 size_t size; /* Size (in blocks) of a free cluster. */
158 size_t next; /* Index of next free cluster. */
159 size_t prev; /* Index of previous free cluster. */
164 /* Internal structure that defines the format of the malloc-descriptor.
165 This gets written to the base address of the region that mmalloc is
166 managing, and thus also becomes the file header for the mapped file,
167 if such a file exists. */
171 /* Semaphore locking the access to the heap */
174 /* Number of processes that attached the heap */
175 unsigned int refcount;
177 /* Chained lists of mdescs */
178 struct mdesc *next_mdesc;
180 /* The "magic number" for an mmalloc file. */
181 char magic[MMALLOC_MAGIC_SIZE];
183 /* The size in bytes of this structure, used as a sanity check when reusing
184 a previously created mapped file. */
185 unsigned int headersize;
187 /* The version number of the mmalloc package that created this file. */
188 unsigned char version;
190 /* Some flag bits to keep track of various internal things. */
193 /* Number of info entries. */
196 /* Pointer to first block of the heap (base of the first block). */
199 /* Current search index for the heap table. */
200 /* Search index in the info table. */
203 /* Limit of valid info table indices. */
206 /* Block information table.
207 Allocated with malign/mfree (not mmalloc/mfree). */
208 /* Table indexed by block number giving per-block information. */
209 malloc_info *heapinfo;
211 /* List of all blocks containing free fragments of this size. The array indice is the log2 of requested size */
212 struct list fraghead[BLOCKLOG];
214 /* The base address of the memory region for this malloc heap. This
215 is the location where the bookkeeping data for mmap and for malloc
220 /* The current location in the memory region for this malloc heap which
221 represents the end of memory in use. */
225 /* The end of the current memory region for this malloc heap. This is
226 the first location past the end of mapped memory. */
230 /* Open file descriptor for the file to which this malloc heap is mapped.
231 This will always be a valid file descriptor, since /dev/zero is used
232 by default if no open file is supplied by the client. Also note that
233 it may change each time the region is mapped and unmapped. */
237 /* Instrumentation. */
239 struct mstats heapstats;
243 /* Bits to look at in the malloc descriptor flags word */
245 #define MMALLOC_DEVZERO (1 << 0) /* Have mapped to /dev/zero */
246 #define MMALLOC_ANONYMOUS (1 << 1) /* Use anonymous mapping */
247 #define MMALLOC_INITIALIZED (1 << 2) /* Initialized mmalloc */
249 /* A default malloc descriptor for the single sbrk() managed region. */
251 extern struct mdesc *__mmalloc_default_mdp;
253 /* Remap a mmalloc region that was previously mapped. */
255 extern void *__mmalloc_remap_core(xbt_mheap_t mdp);
257 /* Get core for the memory region specified by MDP, using SIZE as the
258 amount to either add to or subtract from the existing region. Works
259 like sbrk(), but using mmap(). */
260 extern void *mmorecore(struct mdesc *mdp, int size);
262 /* Thread-safety (if the sem is already created)
264 * This is mandatory in the case where the user runs a parallel simulation
265 * in a model-checking enabled tree. Without this protection, our malloc
266 * implementation will not like multi-threading AT ALL.
268 #define LOCK(mdp) sem_wait(&mdp->sem)
269 #define UNLOCK(mdp) sem_post(&mdp->sem)
271 #endif /* __MMPRIVATE_H */