1 /* Declarations for `mmalloc' and friends. */
3 /* Copyright (c) 2010-2023. The SimGrid Team. All rights reserved. */
5 /* This program is free software; you can redistribute it and/or modify it
6 * under the terms of the license (GNU LGPL) which comes with this package. */
8 /* Copyright 1990, 1991, 1992 Free Software Foundation
10 Written May 1989 by Mike Haertel.
11 Heavily modified Mar 1992 by Fred Fish. (fnf@cygnus.com) */
13 #ifndef XBT_MMPRIVATE_H
14 #define XBT_MMPRIVATE_H 1
16 #include "src/internal_config.h"
17 #include "src/xbt/mmalloc/mmalloc.h"
25 // This macro is veery similar to xbt_assert, but with no dependency on XBT
26 #define mmalloc_assert(cond, ...) \
29 fprintf(stderr, __VA_ARGS__); \
34 XBT_PRIVATE xbt_mheap_t mmalloc_preinit(void);
36 #define MMALLOC_MAGIC "mmalloc" /* Mapped file magic number */
37 #define MMALLOC_MAGIC_SIZE 8 /* Size of magic number buf */
38 #define MMALLOC_VERSION 2 /* Current mmalloc version */
40 /* The allocator divides the heap into blocks of fixed size; large
41 requests receive one or more whole blocks, and small requests
42 receive a fragment of a block. Fragment sizes are powers of two,
43 and all fragments of a block are the same size. When all the
44 fragments in a block have been freed, the block itself is freed.
46 FIXME: we are not targeting 16bits machines anymore; update values */
48 #define INT_BIT (CHAR_BIT * sizeof(int))
49 #define BLOCKLOG (INT_BIT > 16 ? 12 : 9)
50 #define BLOCKSIZE ((unsigned int) 1 << BLOCKLOG)
51 #define BLOCKIFY(SIZE) (((SIZE) + BLOCKSIZE - 1) / BLOCKSIZE)
53 /* We keep fragment-specific meta-data for introspection purposes, and these
54 * information are kept in fixed length arrays. Here is the computation of
57 * Never make SMALLEST_POSSIBLE_MALLOC too small because we need to enlist
60 * FIXME: what's the correct size, actually? The used one is a guess.
63 #define SMALLEST_POSSIBLE_MALLOC (32 * sizeof(void*))
64 #define MAX_FRAGMENT_PER_BLOCK (BLOCKSIZE / SMALLEST_POSSIBLE_MALLOC)
66 /* The difference between two pointers is a signed int. On machines where
67 the data addresses have the high bit set, we need to ensure that the
68 difference becomes an unsigned int when we are using the address as an
69 integral value. In addition, when using with the '%' operator, the
70 sign of the result is machine dependent for negative values, so force
71 it to be treated as an unsigned int. */
73 #define ADDR2UINT(addr) ((uintptr_t) (addr))
74 #define RESIDUAL(addr,bsize) ((uintptr_t) (ADDR2UINT (addr) % (bsize)))
76 /* Determine the amount of memory spanned by the initial heap table
77 (not an absolute limit). */
79 #define HEAP (INT_BIT > 16 ? 4194304 : 65536)
81 /* Number of contiguous free blocks allowed to build up at the end of
82 memory before they will be returned to the system.
83 FIXME: this is not used anymore: we never return memory to the system. */
84 #define FINAL_FREE_BLOCKS 8
86 /* Where to start searching the free list when looking for new memory.
87 The two possible values are 0 and heapindex. Starting at 0 seems
88 to reduce total memory usage, while starting at heapindex seems to
91 #define MALLOC_SEARCH_START mdp -> heapindex
93 /* Address to block number and vice versa. */
95 #define BLOCK(A) ((size_t)(((char*)(A) - (char*)mdp->heapbase) / BLOCKSIZE + 1))
97 #define ADDRESS(B) ((void*) (((ADDR2UINT(B)) - 1) * BLOCKSIZE + (char*) mdp -> heapbase))
101 /* Statistics available to the user. */
104 size_t bytes_total; /* Total size of the heap. */
105 size_t chunks_used; /* Chunks allocated by the user. */
106 size_t bytes_used; /* Byte total of user-allocated chunks. */
107 size_t chunks_free; /* Chunks in the free list. */
108 size_t bytes_free; /* Byte total of chunks in the free list. */
111 #define MMALLOC_TYPE_HEAPINFO (-2)
112 #define MMALLOC_TYPE_FREE (-1)
113 #define MMALLOC_TYPE_UNFRAGMENTED 0
114 /* >0 values are fragmented blocks */
116 /* Data structure giving per-block information.
118 * There is one such structure in the mdp->heapinfo array per block used in that heap,
119 * the array index is the block number.
121 * There is several types of blocks in memory:
122 * - full busy blocks: used when we are asked to malloc a block which size is > BLOCKSIZE/2
123 * In this situation, the full block is given to the malloc.
125 * - fragmented busy blocks: when asked for smaller amount of memory.
126 * Fragment sizes are only power of 2. When looking for such a free fragment,
127 * we get one from mdp->fraghead (that contains a linked list of blocks fragmented at that
128 * size and containing a free fragment), or we get a fresh block that we fragment.
130 * - free blocks are grouped by clusters, that are chained together.
131 * When looking for free blocks, we traverse the mdp->heapinfo looking
132 * for a cluster of free blocks that would be large enough.
134 * The size of the cluster is only to be trusted in the first block of the cluster, not in the middle blocks.
136 * The type field is consistently updated for every blocks, even within clusters of blocks.
137 * You can crawl the array and rely on that value.
141 s_xbt_swag_hookup_t freehook; /* to register this block as having empty frags when needed */
142 int type; /* 0: busy large block
143 >0: busy fragmented (fragments of size 2^type bytes)
147 /* Heap information for a busy block. */
149 size_t nfree; /* Free fragments in a fragmented block. */
150 ssize_t frag_size[MAX_FRAGMENT_PER_BLOCK];
151 int ignore[MAX_FRAGMENT_PER_BLOCK];
154 size_t size; /* Size (in blocks) of a large cluster. */
155 size_t busy_size; /* Actually used space, in bytes */
158 /* Heap information for a free block (that may be the first of a free cluster). */
160 size_t size; /* Size (in blocks) of a free cluster. */
161 size_t next; /* Index of next free cluster. */
162 size_t prev; /* Index of previous free cluster. */
167 /** @brief Descriptor of a mmalloc area
169 * Internal structure that defines the format of the malloc-descriptor.
170 * This gets written to the base address of the region that mmalloc is
171 * managing, and thus also becomes the file header for the mapped file,
172 * if such a file exists.
175 /** @brief Chained lists of mdescs */
176 struct mdesc *next_mdesc;
178 /** @brief The "magic number" for an mmalloc file. */
179 char magic[MMALLOC_MAGIC_SIZE];
181 /** @brief The size in bytes of this structure
183 * Used as a sanity check when reusing a previously created mapped file.
185 unsigned int headersize;
187 /** @brief Version number of the mmalloc package that created this file. */
188 unsigned char version;
190 unsigned int options;
192 /** @brief Some flag bits to keep track of various internal things. */
195 /** @brief Number of info entries. */
198 /** @brief Pointer to first block of the heap (base of the first block). */
201 /** @brief Current search index for the heap table.
203 * Search index in the info table.
207 /** @brief Limit of valid info table indices. */
210 /** @brief Block information table.
212 * Table indexed by block number giving per-block information.
214 malloc_info *heapinfo;
216 /* @brief List of all blocks containing free fragments of a given size.
218 * The array index is the log2 of requested size.
219 * Actually only the sizes 8->11 seem to be used, but who cares? */
220 s_xbt_swag_t fraghead[BLOCKLOG];
222 /* @brief Base address of the memory region for this malloc heap
224 * This is the location where the bookkeeping data for mmap and
229 /** @brief End of memory in use
231 * Some memory might be already mapped by the OS but not used
236 /** @brief End of the current memory region for this malloc heap.
238 * This is the first location past the end of mapped memory.
240 * Compared to breakval, this value is rounded to the next memory page.
244 /* @brief Instrumentation */
245 struct mstats heapstats;
248 /* Bits to look at in the malloc descriptor flags word */
250 #define MMALLOC_DEVZERO (1 << 0) /* Have mapped to /dev/zero */
251 #define MMALLOC_INITIALIZED (1 << 1) /* Initialized mmalloc */
253 /* A default malloc descriptor for the single sbrk() managed region. */
255 XBT_PUBLIC_DATA struct mdesc* __mmalloc_default_mdp;
257 XBT_PUBLIC void* mmorecore(struct mdesc* mdp, ssize_t size);
259 XBT_PRIVATE size_t mmalloc_get_bytes_used_remote(size_t heaplimit, const malloc_info* heapinfo);
261 /* We call dlsym during mmalloc initialization, but dlsym uses malloc.
262 * So during mmalloc initialization, any call to malloc is diverted to a private static buffer.
264 extern uint64_t* mmalloc_preinit_buffer;
265 #ifdef __FreeBSD__ /* FreeBSD require more memory, other might */
266 #define mmalloc_preinit_buffer_size 256
267 #else /* Valid on: Linux */
268 #define mmalloc_preinit_buffer_size 32