| /* |
| A version of malloc/free/realloc written by Doug Lea and released to the |
| public domain. Send questions/comments/complaints/performance data |
| to dl@cs.oswego.edu |
| |
| * VERSION 2.6.6 Sun Mar 5 19:10:03 2000 Doug Lea (dl at gee) |
| |
| Note: There may be an updated version of this malloc obtainable at |
| ftp://g.oswego.edu/pub/misc/malloc.c |
| Check before installing! |
| |
| * Why use this malloc? |
| |
| This is not the fastest, most space-conserving, most portable, or |
| most tunable malloc ever written. However it is among the fastest |
| while also being among the most space-conserving, portable and tunable. |
| Consistent balance across these factors results in a good general-purpose |
| allocator. For a high-level description, see |
| http://g.oswego.edu/dl/html/malloc.html |
| |
| * Synopsis of public routines |
| |
| (Much fuller descriptions are contained in the program documentation below.) |
| |
| malloc(size_t n); |
| Return a pointer to a newly allocated chunk of at least n bytes, or null |
| if no space is available. |
| free(Void_t* p); |
| Release the chunk of memory pointed to by p, or no effect if p is null. |
| realloc(Void_t* p, size_t n); |
| Return a pointer to a chunk of size n that contains the same data |
| as does chunk p up to the minimum of (n, p's size) bytes, or null |
| if no space is available. The returned pointer may or may not be |
| the same as p. If p is null, equivalent to malloc. Unless the |
| #define REALLOC_ZERO_BYTES_FREES below is set, realloc with a |
| size argument of zero (re)allocates a minimum-sized chunk. |
| memalign(size_t alignment, size_t n); |
| Return a pointer to a newly allocated chunk of n bytes, aligned |
| in accord with the alignment argument, which must be a power of |
| two. |
| valloc(size_t n); |
| Equivalent to memalign(pagesize, n), where pagesize is the page |
| size of the system (or as near to this as can be figured out from |
| all the includes/defines below.) |
| pvalloc(size_t n); |
| Equivalent to valloc(minimum-page-that-holds(n)), that is, |
| round up n to nearest pagesize. |
| calloc(size_t unit, size_t quantity); |
| Returns a pointer to quantity * unit bytes, with all locations |
| set to zero. |
| cfree(Void_t* p); |
| Equivalent to free(p). |
| malloc_trim(size_t pad); |
| Release all but pad bytes of freed top-most memory back |
| to the system. Return 1 if successful, else 0. |
| malloc_usable_size(Void_t* p); |
| Report the number usable allocated bytes associated with allocated |
| chunk p. This may or may not report more bytes than were requested, |
| due to alignment and minimum size constraints. |
| malloc_stats(); |
| Prints brief summary statistics on stderr. |
| mallinfo() |
| Returns (by copy) a struct containing various summary statistics. |
| mallopt(int parameter_number, int parameter_value) |
| Changes one of the tunable parameters described below. Returns |
| 1 if successful in changing the parameter, else 0. |
| |
| * Vital statistics: |
| |
| Alignment: 8-byte |
| 8 byte alignment is currently hardwired into the design. This |
| seems to suffice for all current machines and C compilers. |
| |
| Assumed pointer representation: 4 or 8 bytes |
| Code for 8-byte pointers is untested by me but has worked |
| reliably by Wolfram Gloger, who contributed most of the |
| changes supporting this. |
| |
| Assumed size_t representation: 4 or 8 bytes |
| Note that size_t is allowed to be 4 bytes even if pointers are 8. |
| |
| Minimum overhead per allocated chunk: 4 or 8 bytes |
| Each malloced chunk has a hidden overhead of 4 bytes holding size |
| and status information. |
| |
| Minimum allocated size: 4-byte ptrs: 16 bytes (including 4 overhead) |
| 8-byte ptrs: 24/32 bytes (including, 4/8 overhead) |
| |
| When a chunk is freed, 12 (for 4byte ptrs) or 20 (for 8 byte |
| ptrs but 4 byte size) or 24 (for 8/8) additional bytes are |
| needed; 4 (8) for a trailing size field |
| and 8 (16) bytes for free list pointers. Thus, the minimum |
| allocatable size is 16/24/32 bytes. |
| |
| Even a request for zero bytes (i.e., malloc(0)) returns a |
| pointer to something of the minimum allocatable size. |
| |
| Maximum allocated size: 4-byte size_t: 2^31 - 8 bytes |
| 8-byte size_t: 2^63 - 16 bytes |
| |
| It is assumed that (possibly signed) size_t bit values suffice to |
| represent chunk sizes. `Possibly signed' is due to the fact |
| that `size_t' may be defined on a system as either a signed or |
| an unsigned type. To be conservative, values that would appear |
| as negative numbers are avoided. |
| Requests for sizes with a negative sign bit when the request |
| size is treaded as a long will return null. |
| |
| Maximum overhead wastage per allocated chunk: normally 15 bytes |
| |
| Alignnment demands, plus the minimum allocatable size restriction |
| make the normal worst-case wastage 15 bytes (i.e., up to 15 |
| more bytes will be allocated than were requested in malloc), with |
| two exceptions: |
| 1. Because requests for zero bytes allocate non-zero space, |
| the worst case wastage for a request of zero bytes is 24 bytes. |
| 2. For requests >= mmap_threshold that are serviced via |
| mmap(), the worst case wastage is 8 bytes plus the remainder |
| from a system page (the minimal mmap unit); typically 4096 bytes. |
| |
| * Limitations |
| |
| Here are some features that are NOT currently supported |
| |
| * No user-definable hooks for callbacks and the like. |
| * No automated mechanism for fully checking that all accesses |
| to malloced memory stay within their bounds. |
| * No support for compaction. |
| |
| * Synopsis of compile-time options: |
| |
| People have reported using previous versions of this malloc on all |
| versions of Unix, sometimes by tweaking some of the defines |
| below. It has been tested most extensively on Solaris and |
| Linux. It is also reported to work on WIN32 platforms. |
| People have also reported adapting this malloc for use in |
| stand-alone embedded systems. |
| |
| The implementation is in straight, hand-tuned ANSI C. Among other |
| consequences, it uses a lot of macros. Because of this, to be at |
| all usable, this code should be compiled using an optimizing compiler |
| (for example gcc -O2) that can simplify expressions and control |
| paths. |
| |
| __STD_C (default: derived from C compiler defines) |
| Nonzero if using ANSI-standard C compiler, a C++ compiler, or |
| a C compiler sufficiently close to ANSI to get away with it. |
| DEBUG (default: NOT defined) |
| Define to enable debugging. Adds fairly extensive assertion-based |
| checking to help track down memory errors, but noticeably slows down |
| execution. |
| REALLOC_ZERO_BYTES_FREES (default: NOT defined) |
| Define this if you think that realloc(p, 0) should be equivalent |
| to free(p). Otherwise, since malloc returns a unique pointer for |
| malloc(0), so does realloc(p, 0). |
| HAVE_MEMCPY (default: defined) |
| Define if you are not otherwise using ANSI STD C, but still |
| have memcpy and memset in your C library and want to use them. |
| Otherwise, simple internal versions are supplied. |
| USE_MEMCPY (default: 1 if HAVE_MEMCPY is defined, 0 otherwise) |
| Define as 1 if you want the C library versions of memset and |
| memcpy called in realloc and calloc (otherwise macro versions are used). |
| At least on some platforms, the simple macro versions usually |
| outperform libc versions. |
| HAVE_MMAP (default: defined as 1) |
| Define to non-zero to optionally make malloc() use mmap() to |
| allocate very large blocks. |
| HAVE_MREMAP (default: defined as 0 unless Linux libc set) |
| Define to non-zero to optionally make realloc() use mremap() to |
| reallocate very large blocks. |
| malloc_getpagesize (default: derived from system #includes) |
| Either a constant or routine call returning the system page size. |
| HAVE_USR_INCLUDE_MALLOC_H (default: NOT defined) |
| Optionally define if you are on a system with a /usr/include/malloc.h |
| that declares struct mallinfo. It is not at all necessary to |
| define this even if you do, but will ensure consistency. |
| INTERNAL_SIZE_T (default: size_t) |
| Define to a 32-bit type (probably `unsigned int') if you are on a |
| 64-bit machine, yet do not want or need to allow malloc requests of |
| greater than 2^31 to be handled. This saves space, especially for |
| very small chunks. |
| INTERNAL_LINUX_C_LIB (default: NOT defined) |
| Defined only when compiled as part of Linux libc. |
| Also note that there is some odd internal name-mangling via defines |
| (for example, internally, `malloc' is named `mALLOc') needed |
| when compiling in this case. These look funny but don't otherwise |
| affect anything. |
| WIN32 (default: undefined) |
| Define this on MS win (95, nt) platforms to compile in sbrk emulation. |
| LACKS_UNISTD_H (default: undefined if not WIN32) |
| Define this if your system does not have a <unistd.h>. |
| LACKS_SYS_PARAM_H (default: undefined if not WIN32) |
| Define this if your system does not have a <sys/param.h>. |
| MORECORE (default: sbrk) |
| The name of the routine to call to obtain more memory from the system. |
| MORECORE_FAILURE (default: -1) |
| The value returned upon failure of MORECORE. |
| MORECORE_CLEARS (default 1) |
| True (1) if the routine mapped to MORECORE zeroes out memory (which |
| holds for sbrk). |
| DEFAULT_TRIM_THRESHOLD |
| DEFAULT_TOP_PAD |
| DEFAULT_MMAP_THRESHOLD |
| DEFAULT_MMAP_MAX |
| Default values of tunable parameters (described in detail below) |
| controlling interaction with host system routines (sbrk, mmap, etc). |
| These values may also be changed dynamically via mallopt(). The |
| preset defaults are those that give best performance for typical |
| programs/systems. |
| USE_DL_PREFIX (default: undefined) |
| Prefix all public routines with the string 'dl'. Useful to |
| quickly avoid procedure declaration conflicts and linker symbol |
| conflicts with existing memory allocation routines. |
| |
| |
| */ |
| |
| |
| #ifndef __MALLOC_H__ |
| #define __MALLOC_H__ |
| |
| /* Preliminaries */ |
| |
| #ifndef __STD_C |
| #ifdef __STDC__ |
| #define __STD_C 1 |
| #else |
| #if __cplusplus |
| #define __STD_C 1 |
| #else |
| #define __STD_C 0 |
| #endif /*__cplusplus*/ |
| #endif /*__STDC__*/ |
| #endif /*__STD_C*/ |
| |
| #ifndef Void_t |
| #if (__STD_C || defined(WIN32)) |
| #define Void_t void |
| #else |
| #define Void_t char |
| #endif |
| #endif /*Void_t*/ |
| |
| #if __STD_C |
| #include <linux/stddef.h> /* for size_t */ |
| #else |
| #include <sys/types.h> |
| #endif /* __STD_C */ |
| |
| #ifdef __cplusplus |
| extern "C" { |
| #endif |
| |
| #if 0 /* not for U-Boot */ |
| #include <stdio.h> /* needed for malloc_stats */ |
| #endif |
| |
| |
| /* |
| Compile-time options |
| */ |
| |
| |
| /* |
| Debugging: |
| |
| Because freed chunks may be overwritten with link fields, this |
| malloc will often die when freed memory is overwritten by user |
| programs. This can be very effective (albeit in an annoying way) |
| in helping track down dangling pointers. |
| |
| If you compile with -DDEBUG, a number of assertion checks are |
| enabled that will catch more memory errors. You probably won't be |
| able to make much sense of the actual assertion errors, but they |
| should help you locate incorrectly overwritten memory. The |
| checking is fairly extensive, and will slow down execution |
| noticeably. Calling malloc_stats or mallinfo with DEBUG set will |
| attempt to check every non-mmapped allocated and free chunk in the |
| course of computing the summmaries. (By nature, mmapped regions |
| cannot be checked very much automatically.) |
| |
| Setting DEBUG may also be helpful if you are trying to modify |
| this code. The assertions in the check routines spell out in more |
| detail the assumptions and invariants underlying the algorithms. |
| |
| */ |
| |
| /* |
| INTERNAL_SIZE_T is the word-size used for internal bookkeeping |
| of chunk sizes. On a 64-bit machine, you can reduce malloc |
| overhead by defining INTERNAL_SIZE_T to be a 32 bit `unsigned int' |
| at the expense of not being able to handle requests greater than |
| 2^31. This limitation is hardly ever a concern; you are encouraged |
| to set this. However, the default version is the same as size_t. |
| */ |
| |
| #ifndef INTERNAL_SIZE_T |
| #define INTERNAL_SIZE_T size_t |
| #endif |
| |
| /* |
| REALLOC_ZERO_BYTES_FREES should be set if a call to |
| realloc with zero bytes should be the same as a call to free. |
| Some people think it should. Otherwise, since this malloc |
| returns a unique pointer for malloc(0), so does realloc(p, 0). |
| */ |
| |
| |
| /* #define REALLOC_ZERO_BYTES_FREES */ |
| |
| |
| /* |
| WIN32 causes an emulation of sbrk to be compiled in |
| mmap-based options are not currently supported in WIN32. |
| */ |
| |
| /* #define WIN32 */ |
| #ifdef WIN32 |
| #define MORECORE wsbrk |
| #define HAVE_MMAP 0 |
| |
| #define LACKS_UNISTD_H |
| #define LACKS_SYS_PARAM_H |
| |
| /* |
| Include 'windows.h' to get the necessary declarations for the |
| Microsoft Visual C++ data structures and routines used in the 'sbrk' |
| emulation. |
| |
| Define WIN32_LEAN_AND_MEAN so that only the essential Microsoft |
| Visual C++ header files are included. |
| */ |
| #define WIN32_LEAN_AND_MEAN |
| #include <windows.h> |
| #endif |
| |
| |
| /* |
| HAVE_MEMCPY should be defined if you are not otherwise using |
| ANSI STD C, but still have memcpy and memset in your C library |
| and want to use them in calloc and realloc. Otherwise simple |
| macro versions are defined here. |
| |
| USE_MEMCPY should be defined as 1 if you actually want to |
| have memset and memcpy called. People report that the macro |
| versions are often enough faster than libc versions on many |
| systems that it is better to use them. |
| |
| */ |
| |
| #define HAVE_MEMCPY |
| |
| #ifndef USE_MEMCPY |
| #ifdef HAVE_MEMCPY |
| #define USE_MEMCPY 1 |
| #else |
| #define USE_MEMCPY 0 |
| #endif |
| #endif |
| |
| #if (__STD_C || defined(HAVE_MEMCPY)) |
| |
| #if __STD_C |
| void* memset(void*, int, size_t); |
| void* memcpy(void*, const void*, size_t); |
| #else |
| #ifdef WIN32 |
| /* On Win32 platforms, 'memset()' and 'memcpy()' are already declared in */ |
| /* 'windows.h' */ |
| #else |
| Void_t* memset(); |
| Void_t* memcpy(); |
| #endif |
| #endif |
| #endif |
| |
| #if USE_MEMCPY |
| |
| /* The following macros are only invoked with (2n+1)-multiples of |
| INTERNAL_SIZE_T units, with a positive integer n. This is exploited |
| for fast inline execution when n is small. */ |
| |
| #define MALLOC_ZERO(charp, nbytes) \ |
| do { \ |
| INTERNAL_SIZE_T mzsz = (nbytes); \ |
| if(mzsz <= 9*sizeof(mzsz)) { \ |
| INTERNAL_SIZE_T* mz = (INTERNAL_SIZE_T*) (charp); \ |
| if(mzsz >= 5*sizeof(mzsz)) { *mz++ = 0; \ |
| *mz++ = 0; \ |
| if(mzsz >= 7*sizeof(mzsz)) { *mz++ = 0; \ |
| *mz++ = 0; \ |
| if(mzsz >= 9*sizeof(mzsz)) { *mz++ = 0; \ |
| *mz++ = 0; }}} \ |
| *mz++ = 0; \ |
| *mz++ = 0; \ |
| *mz = 0; \ |
| } else memset((charp), 0, mzsz); \ |
| } while(0) |
| |
| #define MALLOC_COPY(dest,src,nbytes) \ |
| do { \ |
| INTERNAL_SIZE_T mcsz = (nbytes); \ |
| if(mcsz <= 9*sizeof(mcsz)) { \ |
| INTERNAL_SIZE_T* mcsrc = (INTERNAL_SIZE_T*) (src); \ |
| INTERNAL_SIZE_T* mcdst = (INTERNAL_SIZE_T*) (dest); \ |
| if(mcsz >= 5*sizeof(mcsz)) { *mcdst++ = *mcsrc++; \ |
| *mcdst++ = *mcsrc++; \ |
| if(mcsz >= 7*sizeof(mcsz)) { *mcdst++ = *mcsrc++; \ |
| *mcdst++ = *mcsrc++; \ |
| if(mcsz >= 9*sizeof(mcsz)) { *mcdst++ = *mcsrc++; \ |
| *mcdst++ = *mcsrc++; }}} \ |
| *mcdst++ = *mcsrc++; \ |
| *mcdst++ = *mcsrc++; \ |
| *mcdst = *mcsrc ; \ |
| } else memcpy(dest, src, mcsz); \ |
| } while(0) |
| |
| #else /* !USE_MEMCPY */ |
| |
| /* Use Duff's device for good zeroing/copying performance. */ |
| |
| #define MALLOC_ZERO(charp, nbytes) \ |
| do { \ |
| INTERNAL_SIZE_T* mzp = (INTERNAL_SIZE_T*)(charp); \ |
| long mctmp = (nbytes)/sizeof(INTERNAL_SIZE_T), mcn; \ |
| if (mctmp < 8) mcn = 0; else { mcn = (mctmp-1)/8; mctmp %= 8; } \ |
| switch (mctmp) { \ |
| case 0: for(;;) { *mzp++ = 0; \ |
| case 7: *mzp++ = 0; \ |
| case 6: *mzp++ = 0; \ |
| case 5: *mzp++ = 0; \ |
| case 4: *mzp++ = 0; \ |
| case 3: *mzp++ = 0; \ |
| case 2: *mzp++ = 0; \ |
| case 1: *mzp++ = 0; if(mcn <= 0) break; mcn--; } \ |
| } \ |
| } while(0) |
| |
| #define MALLOC_COPY(dest,src,nbytes) \ |
| do { \ |
| INTERNAL_SIZE_T* mcsrc = (INTERNAL_SIZE_T*) src; \ |
| INTERNAL_SIZE_T* mcdst = (INTERNAL_SIZE_T*) dest; \ |
| long mctmp = (nbytes)/sizeof(INTERNAL_SIZE_T), mcn; \ |
| if (mctmp < 8) mcn = 0; else { mcn = (mctmp-1)/8; mctmp %= 8; } \ |
| switch (mctmp) { \ |
| case 0: for(;;) { *mcdst++ = *mcsrc++; \ |
| case 7: *mcdst++ = *mcsrc++; \ |
| case 6: *mcdst++ = *mcsrc++; \ |
| case 5: *mcdst++ = *mcsrc++; \ |
| case 4: *mcdst++ = *mcsrc++; \ |
| case 3: *mcdst++ = *mcsrc++; \ |
| case 2: *mcdst++ = *mcsrc++; \ |
| case 1: *mcdst++ = *mcsrc++; if(mcn <= 0) break; mcn--; } \ |
| } \ |
| } while(0) |
| |
| #endif |
| |
| |
| /* |
| Define HAVE_MMAP to optionally make malloc() use mmap() to |
| allocate very large blocks. These will be returned to the |
| operating system immediately after a free(). |
| */ |
| |
| /*** |
| #ifndef HAVE_MMAP |
| #define HAVE_MMAP 1 |
| #endif |
| ***/ |
| #undef HAVE_MMAP /* Not available for U-Boot */ |
| |
| /* |
| Define HAVE_MREMAP to make realloc() use mremap() to re-allocate |
| large blocks. This is currently only possible on Linux with |
| kernel versions newer than 1.3.77. |
| */ |
| |
| /*** |
| #ifndef HAVE_MREMAP |
| #ifdef INTERNAL_LINUX_C_LIB |
| #define HAVE_MREMAP 1 |
| #else |
| #define HAVE_MREMAP 0 |
| #endif |
| #endif |
| ***/ |
| #undef HAVE_MREMAP /* Not available for U-Boot */ |
| |
| #if HAVE_MMAP |
| |
| #include <unistd.h> |
| #include <fcntl.h> |
| #include <sys/mman.h> |
| |
| #if !defined(MAP_ANONYMOUS) && defined(MAP_ANON) |
| #define MAP_ANONYMOUS MAP_ANON |
| #endif |
| |
| #endif /* HAVE_MMAP */ |
| |
| /* |
| Access to system page size. To the extent possible, this malloc |
| manages memory from the system in page-size units. |
| |
| The following mechanics for getpagesize were adapted from |
| bsd/gnu getpagesize.h |
| */ |
| |
| #define LACKS_UNISTD_H /* Shortcut for U-Boot */ |
| #define malloc_getpagesize 4096 |
| |
| #ifndef LACKS_UNISTD_H |
| # include <unistd.h> |
| #endif |
| |
| #ifndef malloc_getpagesize |
| # ifdef _SC_PAGESIZE /* some SVR4 systems omit an underscore */ |
| # ifndef _SC_PAGE_SIZE |
| # define _SC_PAGE_SIZE _SC_PAGESIZE |
| # endif |
| # endif |
| # ifdef _SC_PAGE_SIZE |
| # define malloc_getpagesize sysconf(_SC_PAGE_SIZE) |
| # else |
| # if defined(BSD) || defined(DGUX) || defined(HAVE_GETPAGESIZE) |
| extern size_t getpagesize(); |
| # define malloc_getpagesize getpagesize() |
| # else |
| # ifdef WIN32 |
| # define malloc_getpagesize (4096) /* TBD: Use 'GetSystemInfo' instead */ |
| # else |
| # ifndef LACKS_SYS_PARAM_H |
| # include <sys/param.h> |
| # endif |
| # ifdef EXEC_PAGESIZE |
| # define malloc_getpagesize EXEC_PAGESIZE |
| # else |
| # ifdef NBPG |
| # ifndef CLSIZE |
| # define malloc_getpagesize NBPG |
| # else |
| # define malloc_getpagesize (NBPG * CLSIZE) |
| # endif |
| # else |
| # ifdef NBPC |
| # define malloc_getpagesize NBPC |
| # else |
| # ifdef PAGESIZE |
| # define malloc_getpagesize PAGESIZE |
| # else |
| # define malloc_getpagesize (4096) /* just guess */ |
| # endif |
| # endif |
| # endif |
| # endif |
| # endif |
| # endif |
| # endif |
| #endif |
| |
| |
| /* |
| |
| This version of malloc supports the standard SVID/XPG mallinfo |
| routine that returns a struct containing the same kind of |
| information you can get from malloc_stats. It should work on |
| any SVID/XPG compliant system that has a /usr/include/malloc.h |
| defining struct mallinfo. (If you'd like to install such a thing |
| yourself, cut out the preliminary declarations as described above |
| and below and save them in a malloc.h file. But there's no |
| compelling reason to bother to do this.) |
| |
| The main declaration needed is the mallinfo struct that is returned |
| (by-copy) by mallinfo(). The SVID/XPG malloinfo struct contains a |
| bunch of fields, most of which are not even meaningful in this |
| version of malloc. Some of these fields are are instead filled by |
| mallinfo() with other numbers that might possibly be of interest. |
| |
| HAVE_USR_INCLUDE_MALLOC_H should be set if you have a |
| /usr/include/malloc.h file that includes a declaration of struct |
| mallinfo. If so, it is included; else an SVID2/XPG2 compliant |
| version is declared below. These must be precisely the same for |
| mallinfo() to work. |
| |
| */ |
| |
| /* #define HAVE_USR_INCLUDE_MALLOC_H */ |
| |
| #if HAVE_USR_INCLUDE_MALLOC_H |
| #include "/usr/include/malloc.h" |
| #else |
| |
| /* SVID2/XPG mallinfo structure */ |
| |
| struct mallinfo { |
| int arena; /* total space allocated from system */ |
| int ordblks; /* number of non-inuse chunks */ |
| int smblks; /* unused -- always zero */ |
| int hblks; /* number of mmapped regions */ |
| int hblkhd; /* total space in mmapped regions */ |
| int usmblks; /* unused -- always zero */ |
| int fsmblks; /* unused -- always zero */ |
| int uordblks; /* total allocated space */ |
| int fordblks; /* total non-inuse space */ |
| int keepcost; /* top-most, releasable (via malloc_trim) space */ |
| }; |
| |
| /* SVID2/XPG mallopt options */ |
| |
| #define M_MXFAST 1 /* UNUSED in this malloc */ |
| #define M_NLBLKS 2 /* UNUSED in this malloc */ |
| #define M_GRAIN 3 /* UNUSED in this malloc */ |
| #define M_KEEP 4 /* UNUSED in this malloc */ |
| |
| #endif |
| |
| /* mallopt options that actually do something */ |
| |
| #define M_TRIM_THRESHOLD -1 |
| #define M_TOP_PAD -2 |
| #define M_MMAP_THRESHOLD -3 |
| #define M_MMAP_MAX -4 |
| |
| |
| #ifndef DEFAULT_TRIM_THRESHOLD |
| #define DEFAULT_TRIM_THRESHOLD (128 * 1024) |
| #endif |
| |
| /* |
| M_TRIM_THRESHOLD is the maximum amount of unused top-most memory |
| to keep before releasing via malloc_trim in free(). |
| |
| Automatic trimming is mainly useful in long-lived programs. |
| Because trimming via sbrk can be slow on some systems, and can |
| sometimes be wasteful (in cases where programs immediately |
| afterward allocate more large chunks) the value should be high |
| enough so that your overall system performance would improve by |
| releasing. |
| |
| The trim threshold and the mmap control parameters (see below) |
| can be traded off with one another. Trimming and mmapping are |
| two different ways of releasing unused memory back to the |
| system. Between these two, it is often possible to keep |
| system-level demands of a long-lived program down to a bare |
| minimum. For example, in one test suite of sessions measuring |
| the XF86 X server on Linux, using a trim threshold of 128K and a |
| mmap threshold of 192K led to near-minimal long term resource |
| consumption. |
| |
| If you are using this malloc in a long-lived program, it should |
| pay to experiment with these values. As a rough guide, you |
| might set to a value close to the average size of a process |
| (program) running on your system. Releasing this much memory |
| would allow such a process to run in memory. Generally, it's |
| worth it to tune for trimming rather tham memory mapping when a |
| program undergoes phases where several large chunks are |
| allocated and released in ways that can reuse each other's |
| storage, perhaps mixed with phases where there are no such |
| chunks at all. And in well-behaved long-lived programs, |
| controlling release of large blocks via trimming versus mapping |
| is usually faster. |
| |
| However, in most programs, these parameters serve mainly as |
| protection against the system-level effects of carrying around |
| massive amounts of unneeded memory. Since frequent calls to |
| sbrk, mmap, and munmap otherwise degrade performance, the default |
| parameters are set to relatively high values that serve only as |
| safeguards. |
| |
| The default trim value is high enough to cause trimming only in |
| fairly extreme (by current memory consumption standards) cases. |
| It must be greater than page size to have any useful effect. To |
| disable trimming completely, you can set to (unsigned long)(-1); |
| |
| |
| */ |
| |
| |
| #ifndef DEFAULT_TOP_PAD |
| #define DEFAULT_TOP_PAD (0) |
| #endif |
| |
| /* |
| M_TOP_PAD is the amount of extra `padding' space to allocate or |
| retain whenever sbrk is called. It is used in two ways internally: |
| |
| * When sbrk is called to extend the top of the arena to satisfy |
| a new malloc request, this much padding is added to the sbrk |
| request. |
| |
| * When malloc_trim is called automatically from free(), |
| it is used as the `pad' argument. |
| |
| In both cases, the actual amount of padding is rounded |
| so that the end of the arena is always a system page boundary. |
| |
| The main reason for using padding is to avoid calling sbrk so |
| often. Having even a small pad greatly reduces the likelihood |
| that nearly every malloc request during program start-up (or |
| after trimming) will invoke sbrk, which needlessly wastes |
| time. |
| |
| Automatic rounding-up to page-size units is normally sufficient |
| to avoid measurable overhead, so the default is 0. However, in |
| systems where sbrk is relatively slow, it can pay to increase |
| this value, at the expense of carrying around more memory than |
| the program needs. |
| |
| */ |
| |
| |
| #ifndef DEFAULT_MMAP_THRESHOLD |
| #define DEFAULT_MMAP_THRESHOLD (128 * 1024) |
| #endif |
| |
| /* |
| |
| M_MMAP_THRESHOLD is the request size threshold for using mmap() |
| to service a request. Requests of at least this size that cannot |
| be allocated using already-existing space will be serviced via mmap. |
| (If enough normal freed space already exists it is used instead.) |
| |
| Using mmap segregates relatively large chunks of memory so that |
| they can be individually obtained and released from the host |
| system. A request serviced through mmap is never reused by any |
| other request (at least not directly; the system may just so |
| happen to remap successive requests to the same locations). |
| |
| Segregating space in this way has the benefit that mmapped space |
| can ALWAYS be individually released back to the system, which |
| helps keep the system level memory demands of a long-lived |
| program low. Mapped memory can never become `locked' between |
| other chunks, as can happen with normally allocated chunks, which |
| menas that even trimming via malloc_trim would not release them. |
| |
| However, it has the disadvantages that: |
| |
| 1. The space cannot be reclaimed, consolidated, and then |
| used to service later requests, as happens with normal chunks. |
| 2. It can lead to more wastage because of mmap page alignment |
| requirements |
| 3. It causes malloc performance to be more dependent on host |
| system memory management support routines which may vary in |
| implementation quality and may impose arbitrary |
| limitations. Generally, servicing a request via normal |
| malloc steps is faster than going through a system's mmap. |
| |
| All together, these considerations should lead you to use mmap |
| only for relatively large requests. |
| |
| |
| */ |
| |
| |
| #ifndef DEFAULT_MMAP_MAX |
| #if HAVE_MMAP |
| #define DEFAULT_MMAP_MAX (64) |
| #else |
| #define DEFAULT_MMAP_MAX (0) |
| #endif |
| #endif |
| |
| /* |
| M_MMAP_MAX is the maximum number of requests to simultaneously |
| service using mmap. This parameter exists because: |
| |
| 1. Some systems have a limited number of internal tables for |
| use by mmap. |
| 2. In most systems, overreliance on mmap can degrade overall |
| performance. |
| 3. If a program allocates many large regions, it is probably |
| better off using normal sbrk-based allocation routines that |
| can reclaim and reallocate normal heap memory. Using a |
| small value allows transition into this mode after the |
| first few allocations. |
| |
| Setting to 0 disables all use of mmap. If HAVE_MMAP is not set, |
| the default value is 0, and attempts to set it to non-zero values |
| in mallopt will fail. |
| */ |
| |
| |
| /* |
| USE_DL_PREFIX will prefix all public routines with the string 'dl'. |
| Useful to quickly avoid procedure declaration conflicts and linker |
| symbol conflicts with existing memory allocation routines. |
| |
| */ |
| |
| /* #define USE_DL_PREFIX */ |
| |
| |
| /* |
| |
| Special defines for linux libc |
| |
| Except when compiled using these special defines for Linux libc |
| using weak aliases, this malloc is NOT designed to work in |
| multithreaded applications. No semaphores or other concurrency |
| control are provided to ensure that multiple malloc or free calls |
| don't run at the same time, which could be disasterous. A single |
| semaphore could be used across malloc, realloc, and free (which is |
| essentially the effect of the linux weak alias approach). It would |
| be hard to obtain finer granularity. |
| |
| */ |
| |
| |
| #ifdef INTERNAL_LINUX_C_LIB |
| |
| #if __STD_C |
| |
| Void_t * __default_morecore_init (ptrdiff_t); |
| Void_t *(*__morecore)(ptrdiff_t) = __default_morecore_init; |
| |
| #else |
| |
| Void_t * __default_morecore_init (); |
| Void_t *(*__morecore)() = __default_morecore_init; |
| |
| #endif |
| |
| #define MORECORE (*__morecore) |
| #define MORECORE_FAILURE 0 |
| #define MORECORE_CLEARS 1 |
| |
| #else /* INTERNAL_LINUX_C_LIB */ |
| |
| #if __STD_C |
| extern Void_t* sbrk(ptrdiff_t); |
| #else |
| extern Void_t* sbrk(); |
| #endif |
| |
| #ifndef MORECORE |
| #define MORECORE sbrk |
| #endif |
| |
| #ifndef MORECORE_FAILURE |
| #define MORECORE_FAILURE -1 |
| #endif |
| |
| #ifndef MORECORE_CLEARS |
| #define MORECORE_CLEARS 1 |
| #endif |
| |
| #endif /* INTERNAL_LINUX_C_LIB */ |
| |
| #if defined(INTERNAL_LINUX_C_LIB) && defined(__ELF__) |
| |
| #define cALLOc __libc_calloc |
| #define fREe __libc_free |
| #define mALLOc __libc_malloc |
| #define mEMALIGn __libc_memalign |
| #define rEALLOc __libc_realloc |
| #define vALLOc __libc_valloc |
| #define pvALLOc __libc_pvalloc |
| #define mALLINFo __libc_mallinfo |
| #define mALLOPt __libc_mallopt |
| |
| #pragma weak calloc = __libc_calloc |
| #pragma weak free = __libc_free |
| #pragma weak cfree = __libc_free |
| #pragma weak malloc = __libc_malloc |
| #pragma weak memalign = __libc_memalign |
| #pragma weak realloc = __libc_realloc |
| #pragma weak valloc = __libc_valloc |
| #pragma weak pvalloc = __libc_pvalloc |
| #pragma weak mallinfo = __libc_mallinfo |
| #pragma weak mallopt = __libc_mallopt |
| |
| #else |
| |
| #ifdef USE_DL_PREFIX |
| #define cALLOc dlcalloc |
| #define fREe dlfree |
| #define mALLOc dlmalloc |
| #define mEMALIGn dlmemalign |
| #define rEALLOc dlrealloc |
| #define vALLOc dlvalloc |
| #define pvALLOc dlpvalloc |
| #define mALLINFo dlmallinfo |
| #define mALLOPt dlmallopt |
| #else /* USE_DL_PREFIX */ |
| #define cALLOc calloc |
| #define fREe free |
| #define mALLOc malloc |
| #define mEMALIGn memalign |
| #define rEALLOc realloc |
| #define vALLOc valloc |
| #define pvALLOc pvalloc |
| #define mALLINFo mallinfo |
| #define mALLOPt mallopt |
| #endif /* USE_DL_PREFIX */ |
| |
| #endif |
| |
| /* Public routines */ |
| |
| #if __STD_C |
| |
| Void_t* mALLOc(size_t); |
| void fREe(Void_t*); |
| Void_t* rEALLOc(Void_t*, size_t); |
| Void_t* mEMALIGn(size_t, size_t); |
| Void_t* vALLOc(size_t); |
| Void_t* pvALLOc(size_t); |
| Void_t* cALLOc(size_t, size_t); |
| void cfree(Void_t*); |
| int malloc_trim(size_t); |
| size_t malloc_usable_size(Void_t*); |
| void malloc_stats(void); |
| int mALLOPt(int, int); |
| struct mallinfo mALLINFo(void); |
| #else |
| Void_t* mALLOc(); |
| void fREe(); |
| Void_t* rEALLOc(); |
| Void_t* mEMALIGn(); |
| Void_t* vALLOc(); |
| Void_t* pvALLOc(); |
| Void_t* cALLOc(); |
| void cfree(); |
| int malloc_trim(); |
| size_t malloc_usable_size(); |
| void malloc_stats(); |
| int mALLOPt(); |
| struct mallinfo mALLINFo(); |
| #endif |
| |
| /* |
| * Begin and End of memory area for malloc(), and current "brk" |
| */ |
| extern ulong mem_malloc_start; |
| extern ulong mem_malloc_end; |
| extern ulong mem_malloc_brk; |
| |
| void mem_malloc_init(ulong start, ulong size); |
| |
| #ifdef __cplusplus |
| }; /* end of extern "C" */ |
| #endif |
| |
| #endif /* __MALLOC_H__ */ |
