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 <semaphore.h>
30 #define MMALLOC_MAGIC "mmalloc" /* Mapped file magic number */
31 #define MMALLOC_MAGIC_SIZE 8 /* Size of magic number buf */
32 #define MMALLOC_VERSION 1 /* Current mmalloc version */
34 /* The allocator divides the heap into blocks of fixed size; large
35 requests receive one or more whole blocks, and small requests
36 receive a fragment of a block. Fragment sizes are powers of two,
37 and all fragments of a block are the same size. When all the
38 fragments in a block have been freed, the block itself is freed. */
40 #define INT_BIT (CHAR_BIT * sizeof(int))
41 #define BLOCKLOG (INT_BIT > 16 ? 12 : 9)
42 #define BLOCKSIZE ((unsigned int) 1 << BLOCKLOG)
43 #define BLOCKIFY(SIZE) (((SIZE) + BLOCKSIZE - 1) / BLOCKSIZE)
45 /* The difference between two pointers is a signed int. On machines where
46 the data addresses have the high bit set, we need to ensure that the
47 difference becomes an unsigned int when we are using the address as an
48 integral value. In addition, when using with the '%' operator, the
49 sign of the result is machine dependent for negative values, so force
50 it to be treated as an unsigned int. */
52 #define ADDR2UINT(addr) ((unsigned int) ((char*) (addr) - (char*) NULL))
53 #define RESIDUAL(addr,bsize) ((unsigned int) (ADDR2UINT (addr) % (bsize)))
55 /* Determine the amount of memory spanned by the initial heap table
56 (not an absolute limit). */
58 #define HEAP (INT_BIT > 16 ? 4194304 : 65536)
60 /* Number of contiguous free blocks allowed to build up at the end of
61 memory before they will be returned to the system. */
63 #define FINAL_FREE_BLOCKS 8
65 /* Where to start searching the free list when looking for new memory.
66 The two possible values are 0 and heapindex. Starting at 0 seems
67 to reduce total memory usage, while starting at heapindex seems to
70 #define MALLOC_SEARCH_START mdp -> heapindex
72 /* Address to block number and vice versa. */
74 #define BLOCK(A) (((char*) (A) - (char*) mdp -> heapbase) / BLOCKSIZE + 1)
76 #define ADDRESS(B) ((void*) (((ADDR2UINT(B)) - 1) * BLOCKSIZE + (char*) mdp -> heapbase))
78 const char *xbt_thread_self_name(void);
80 /* Data structure giving per-block information.
82 * There is one such structure in the mdp->heapinfo array,
83 * that is addressed by block number.
85 * There is several types of blocks in memory:
86 * - full busy blocks: used when we are asked to malloc a block which size is > BLOCKSIZE/2
87 * In this situation, the full block is given to the malloc.
89 * - fragmented busy blocks: when asked for smaller amount of memory.
90 * Fragment sizes are only power of 2. When looking for such a free fragment,
91 * we get one from mdp->fraghead (that contains a linked list of blocks fragmented at that
92 * size and containing a free fragment), or we get a fresh block that we fragment.
94 * - free blocks are grouped by clusters, that are chained together.
95 * When looking for free blocks, we traverse the mdp->heapinfo looking
96 * for a cluster of free blocks that would be large enough.
98 * The size of the cluster is only to be trusted in the first block of the cluster.
99 * If the cluster results of the fusion of several clusters, the previously first
100 * block of their cluster will have partial data. The only information kept consistent over
101 * all blocks of the clusters is their type (== -1).
103 * Note that there is no way to determine if the block is free or busy by exploring
104 * this structure only. It wasn't intended to be crawled for comparison and we should fix it (TODO).
106 * TODO: understand whether the information are written in each blocks of a cluster (be it
107 * free or busy) or only in the first block of the cluster. And in the latter case, how can
108 * I retrieve the first block of my cluster.
111 * - add an indication of the requested size in each fragment, similarly to busy_block.busy_size
112 * - make room to store the backtrace of where the blocks and fragment were malloced, too.
115 int type; /* 0: busy large block
116 >0: busy fragmented (fragments of size 2^type bytes)
119 /* Heap information for a busy block. */
121 size_t nfree; /* Free fragments in a fragmented block. */
122 size_t first; /* First free fragment of the block. */
125 size_t size; /* Size (in blocks) of a large cluster. */
126 size_t busy_size; /* Actually used space, in bytes */
128 /* Heap information for a free block (that may be the first of a free cluster). */
130 size_t size; /* Size (in blocks) of a free cluster. */
131 size_t next; /* Index of next free cluster. */
132 size_t prev; /* Index of previous free cluster. */
137 /* Doubly linked lists of free fragments. */
143 /* Internal structure that defines the format of the malloc-descriptor.
144 This gets written to the base address of the region that mmalloc is
145 managing, and thus also becomes the file header for the mapped file,
146 if such a file exists. */
150 /* Semaphore locking the access to the heap */
153 /* Number of processes that attached the heap */
154 unsigned int refcount;
156 /* Chained lists of mdescs */
157 struct mdesc *next_mdesc;
159 /* The "magic number" for an mmalloc file. */
160 char magic[MMALLOC_MAGIC_SIZE];
162 /* The size in bytes of this structure, used as a sanity check when reusing
163 a previously created mapped file. */
164 unsigned int headersize;
166 /* The version number of the mmalloc package that created this file. */
167 unsigned char version;
169 /* Some flag bits to keep track of various internal things. */
172 /* Number of info entries. */
175 /* Pointer to first block of the heap (base of the first block). */
178 /* Current search index for the heap table. */
179 /* Search index in the info table. */
182 /* Limit of valid info table indices. */
185 /* Block information table.
186 Allocated with malign/__mmalloc_free (not mmalloc/mfree). */
187 /* Table indexed by block number giving per-block information. */
188 malloc_info *heapinfo;
190 /* List of all blocks containing free fragments of this size. The array indice is the log2 of requested size */
191 struct list fraghead[BLOCKLOG];
193 /* The base address of the memory region for this malloc heap. This
194 is the location where the bookkeeping data for mmap and for malloc
199 /* The current location in the memory region for this malloc heap which
200 represents the end of memory in use. */
204 /* The end of the current memory region for this malloc heap. This is
205 the first location past the end of mapped memory. */
209 /* Open file descriptor for the file to which this malloc heap is mapped.
210 This will always be a valid file descriptor, since /dev/zero is used
211 by default if no open file is supplied by the client. Also note that
212 it may change each time the region is mapped and unmapped. */
218 int mmalloc_compare_mdesc(struct mdesc *mdp1, struct mdesc *mdp2, void *std_heap_addr);
220 void mmalloc_display_info(void *h);
222 /* Bits to look at in the malloc descriptor flags word */
224 #define MMALLOC_DEVZERO (1 << 0) /* Have mapped to /dev/zero */
225 #define MMALLOC_ANONYMOUS (1 << 1) /* Use anonymous mapping */
226 #define MMALLOC_INITIALIZED (1 << 2) /* Initialized mmalloc */
228 /* Internal version of `mfree' used in `morecore'. */
230 extern void __mmalloc_free(struct mdesc *mdp, void *ptr);
232 /* A default malloc descriptor for the single sbrk() managed region. */
234 extern struct mdesc *__mmalloc_default_mdp;
236 /* Remap a mmalloc region that was previously mapped. */
238 extern void *__mmalloc_remap_core(xbt_mheap_t mdp);
240 /* Get core for the memory region specified by MDP, using SIZE as the
241 amount to either add to or subtract from the existing region. Works
242 like sbrk(), but using mmap(). */
243 extern void *mmorecore(struct mdesc *mdp, int size);
245 /* Thread-safety (if the sem is already created) FIXME: KILLIT*/
249 #define UNLOCK(mdp) \
252 #endif /* __MMPRIVATE_H */