6 Here are some notes on configuring Perl's malloc. (For non-perl
9 There are two macros which serve as bulk disablers of advanced
10 features of this malloc: NO_FANCY_MALLOC, PLAIN_MALLOC (undef by
11 default). Look in the list of default values below to understand
12 their exact effect. Defining NO_FANCY_MALLOC returns malloc.c to the
13 state of the malloc in Perl 5.004. Additionally defining PLAIN_MALLOC
14 returns it to the state as of Perl 5.000.
16 Note that some of the settings below may be ignored in the code based
17 on values of other macros. The PERL_CORE symbol is only defined when
18 perl itself is being compiled (so malloc can make some assumptions
19 about perl's facilities being available to it).
21 Each config option has a short description, followed by its name,
22 default value, and a comment about the default (if applicable). Some
23 options take a precise value, while the others are just boolean.
24 The boolean ones are listed first.
26 # Enable code for an emergency memory pool in $^M. See perlvar.pod
27 # for a description of $^M.
28 PERL_EMERGENCY_SBRK (!PLAIN_MALLOC && PERL_CORE)
30 # Enable code for printing memory statistics.
31 DEBUGGING_MSTATS (!PLAIN_MALLOC && PERL_CORE)
33 # Move allocation info for small buckets into separate areas.
34 # Memory optimization (especially for small allocations, of the
35 # less than 64 bytes). Since perl usually makes a large number
36 # of small allocations, this is usually a win.
37 PACK_MALLOC (!PLAIN_MALLOC && !RCHECK)
39 # Add one page to big powers of two when calculating bucket size.
40 # This is targeted at big allocations, as are common in image
42 TWO_POT_OPTIMIZE !PLAIN_MALLOC
44 # Use intermediate bucket sizes between powers-of-two. This is
45 # generally a memory optimization, and a (small) speed pessimization.
46 BUCKETS_ROOT2 !NO_FANCY_MALLOC
48 # Do not check small deallocations for bad free(). Memory
49 # and speed optimization, error reporting pessimization.
50 IGNORE_SMALL_BAD_FREE (!NO_FANCY_MALLOC && !RCHECK)
52 # Use table lookup to decide in which bucket a given allocation will go.
53 SMALL_BUCKET_VIA_TABLE !NO_FANCY_MALLOC
55 # Use a perl-defined sbrk() instead of the (presumably broken or
56 # missing) system-supplied sbrk().
59 # Use system malloc() (or calloc() etc.) to emulate sbrk(). Normally
60 # only used with broken sbrk()s.
61 PERL_SBRK_VIA_MALLOC undef
63 # Which allocator to use if PERL_SBRK_VIA_MALLOC
64 SYSTEM_ALLOC(a) malloc(a)
66 # Minimal alignment (in bytes, should be a power of 2) of SYSTEM_ALLOC
67 SYSTEM_ALLOC_ALIGNMENT MEM_ALIGNBYTES
69 # Disable memory overwrite checking with DEBUGGING. Memory and speed
70 # optimization, error reporting pessimization.
73 # Enable memory overwrite checking with DEBUGGING. Memory and speed
74 # pessimization, error reporting optimization
75 RCHECK (DEBUGGING && !NO_RCHECK)
77 # Failed allocations bigger than this size croak (if
78 # PERL_EMERGENCY_SBRK is enabled) without touching $^M. See
79 # perlvar.pod for a description of $^M.
80 BIG_SIZE (1<<16) # 64K
82 # Starting from this power of two, add an extra page to the
83 # size of the bucket. This enables optimized allocations of sizes
84 # close to powers of 2. Note that the value is indexed at 0.
85 FIRST_BIG_POW2 15 # 32K, 16K is used too often
87 # Estimate of minimal memory footprint. malloc uses this value to
88 # request the most reasonable largest blocks of memory from the system.
91 # Round up sbrk()s to multiples of this.
94 # Round up sbrk()s to multiples of this percent of footprint.
97 # Add this much memory to big powers of two to get the bucket size.
100 # This many sbrk() discontinuities should be tolerated even
101 # from the start without deciding that sbrk() is usually
103 SBRK_ALLOW_FAILURES 3
105 # This many continuous sbrk()s compensate for one discontinuous one.
106 SBRK_FAILURE_PRICE 50
108 # Some configurations may ask for 12-byte-or-so allocations which
109 # require 8-byte alignment (?!). In such situation one needs to
110 # define this to disable 12-byte bucket (will increase memory footprint)
111 STRICT_ALIGNMENT undef
113 This implementation assumes that calling PerlIO_printf() does not
114 result in any memory allocation calls (used during a panic).
119 If used outside of Perl environment, it may be useful to redefine
120 the following macros (listed below with defaults):
122 # Type of address returned by allocation functions
125 # Type of size argument for allocation functions
126 MEM_SIZE unsigned long
128 # Maximal value in LONG
131 # Unsigned integer type big enough to keep a pointer
134 # Type of pointer with 1-byte granularity
137 # Type returned by free()
140 # Very fatal condition reporting function (cannot call any )
141 fatalcroak(arg) write(2,arg,strlen(arg)) + exit(2)
143 # Fatal error reporting function
144 croak(format, arg) warn(idem) + exit(1)
146 # Error reporting function
147 warn(format, arg) fprintf(stderr, idem)
149 # Locking/unlocking for MT operation
150 MALLOC_LOCK MUTEX_LOCK_NOCONTEXT(&PL_malloc_mutex)
151 MALLOC_UNLOCK MUTEX_UNLOCK_NOCONTEXT(&PL_malloc_mutex)
153 # Locking/unlocking mutex for MT operation
158 #ifndef NO_FANCY_MALLOC
159 # ifndef SMALL_BUCKET_VIA_TABLE
160 # define SMALL_BUCKET_VIA_TABLE
162 # ifndef BUCKETS_ROOT2
163 # define BUCKETS_ROOT2
165 # ifndef IGNORE_SMALL_BAD_FREE
166 # define IGNORE_SMALL_BAD_FREE
170 #ifndef PLAIN_MALLOC /* Bulk enable features */
174 # ifndef TWO_POT_OPTIMIZE
175 # define TWO_POT_OPTIMIZE
177 # if defined(PERL_CORE) && !defined(PERL_EMERGENCY_SBRK)
178 # define PERL_EMERGENCY_SBRK
180 # if defined(PERL_CORE) && !defined(DEBUGGING_MSTATS)
181 # define DEBUGGING_MSTATS
185 #define MIN_BUC_POW2 (sizeof(void*) > 4 ? 3 : 2) /* Allow for 4-byte arena. */
186 #define MIN_BUCKET (MIN_BUC_POW2 * BUCKETS_PER_POW2)
188 #if !(defined(I286) || defined(atarist) || defined(__MINT__))
189 /* take 2k unless the block is bigger than that */
190 # define LOG_OF_MIN_ARENA 11
192 /* take 16k unless the block is bigger than that
193 (80286s like large segments!), probably good on the atari too */
194 # define LOG_OF_MIN_ARENA 14
198 # if defined(DEBUGGING) && !defined(NO_RCHECK)
201 # if defined(RCHECK) && defined(IGNORE_SMALL_BAD_FREE)
202 # undef IGNORE_SMALL_BAD_FREE
205 * malloc.c (Caltech) 2/21/82
206 * Chris Kingsley, kingsley@cit-20.
208 * This is a very fast storage allocator. It allocates blocks of a small
209 * number of different sizes, and keeps free lists of each size. Blocks that
210 * don't exactly fit are passed up to the next larger size. In this
211 * implementation, the available sizes are 2^n-4 (or 2^n-12) bytes long.
212 * If PACK_MALLOC is defined, small blocks are 2^n bytes long.
213 * This is designed for use in a program that uses vast quantities of memory,
214 * but bombs when it runs out.
216 * Modifications Copyright Ilya Zakharevich 1996-99.
218 * Still very quick, but much more thrifty. (Std config is 10% slower
219 * than it was, and takes 67% of old heap size for typical usage.)
221 * Allocations of small blocks are now table-driven to many different
222 * buckets. Sizes of really big buckets are increased to accomodata
223 * common size=power-of-2 blocks. Running-out-of-memory is made into
224 * an exception. Deeply configurable and thread-safe.
230 #define PERL_IN_MALLOC_C
232 # if defined(PERL_IMPLICIT_CONTEXT)
233 # define croak Perl_croak_nocontext
234 # define warn Perl_warn_nocontext
238 # include "../EXTERN.h"
239 # include "../perl.h"
246 # define Malloc_t void *
249 # define MEM_SIZE unsigned long
252 # define LONG_MAX 0x7FFFFFFF
255 # define UV unsigned long
258 # define caddr_t char *
263 # define Copy(s,d,n,t) (void)memcpy((char*)(d),(char*)(s), (n) * sizeof(t))
264 # define PerlEnv_getenv getenv
265 # define PerlIO_printf fprintf
266 # define PerlIO_stderr() stderr
268 # ifndef croak /* make depend */
269 # define croak(mess, arg) (warn((mess), (arg)), exit(1))
272 # define warn(mess, arg) fprintf(stderr, (mess), (arg))
284 # define dTHX extern int Perl___notused
285 # define WITH_THX(s) s
290 # define MUTEX_LOCK(l)
294 # define MUTEX_UNLOCK(l)
298 # define MALLOC_LOCK MUTEX_LOCK_NOCONTEXT(&PL_malloc_mutex)
301 #ifndef MALLOC_UNLOCK
302 # define MALLOC_UNLOCK MUTEX_UNLOCK_NOCONTEXT(&PL_malloc_mutex)
305 # ifndef fatalcroak /* make depend */
306 # define fatalcroak(mess) (write(2, (mess), strlen(mess)), exit(2))
311 # define DEBUG_m(a) if (PL_curinterp && PL_debug & 128) a
317 * The memory is broken into "blocks" which occupy multiples of 2K (and
318 * generally speaking, have size "close" to a power of 2). The addresses
319 * of such *unused* blocks are kept in nextf[i] with big enough i. (nextf
320 * is an array of linked lists.) (Addresses of used blocks are not known.)
322 * Moreover, since the algorithm may try to "bite" smaller blocks of out
323 * of unused bigger ones, there are also regions of "irregular" size,
324 * managed separately, by a linked list chunk_chain.
326 * The third type of storage is the sbrk()ed-but-not-yet-used space, its
327 * end and size are kept in last_sbrk_top and sbrked_remains.
329 * Growing blocks "in place":
330 * ~~~~~~~~~~~~~~~~~~~~~~~~~
331 * The address of the block with the greatest address is kept in last_op
332 * (if not known, last_op is 0). If it is known that the memory above
333 * last_op is not continuous, or contains a chunk from chunk_chain,
334 * last_op is set to 0.
336 * The chunk with address last_op may be grown by expanding into
337 * sbrk()ed-but-not-yet-used space, or trying to sbrk() more continuous
340 * Management of last_op:
341 * ~~~~~~~~~~~~~~~~~~~~~
343 * free() never changes the boundaries of blocks, so is not relevant.
345 * The only way realloc() may change the boundaries of blocks is if it
346 * grows a block "in place". However, in the case of success such a
347 * chunk is automatically last_op, and it remains last_op. In the case
348 * of failure getpages_adjacent() clears last_op.
350 * malloc() may change blocks by calling morecore() only.
352 * morecore() may create new blocks by:
353 * a) biting pieces from chunk_chain (cannot create one above last_op);
354 * b) biting a piece from an unused block (if block was last_op, this
355 * may create a chunk from chain above last_op, thus last_op is
356 * invalidated in such a case).
357 * c) biting of sbrk()ed-but-not-yet-used space. This creates
358 * a block which is last_op.
359 * d) Allocating new pages by calling getpages();
361 * getpages() creates a new block. It marks last_op at the bottom of
362 * the chunk of memory it returns.
364 * Active pages footprint:
365 * ~~~~~~~~~~~~~~~~~~~~~~
366 * Note that we do not need to traverse the lists in nextf[i], just take
367 * the first element of this list. However, we *need* to traverse the
368 * list in chunk_chain, but most the time it should be a very short one,
369 * so we do not step on a lot of pages we are not going to use.
373 * get_from_bigger_buckets(): forget to increment price => Quite
377 /* I don't much care whether these are defined in sys/types.h--LAW */
379 #define u_char unsigned char
380 #define u_int unsigned int
383 # define u_bigint UV /* Needs to eat *void. */
385 # define u_bigint unsigned long /* Needs to eat *void. */
388 #define u_short unsigned short
390 /* 286 and atarist like big chunks, which gives too much overhead. */
391 #if (defined(RCHECK) || defined(I286) || defined(atarist) || defined(__MINT__)) && defined(PACK_MALLOC)
396 * The description below is applicable if PACK_MALLOC is not defined.
398 * The overhead on a block is at least 4 bytes. When free, this space
399 * contains a pointer to the next free block, and the bottom two bits must
400 * be zero. When in use, the first byte is set to MAGIC, and the second
401 * byte is the size index. The remaining bytes are for alignment.
402 * If range checking is enabled and the size of the block fits
403 * in two bytes, then the top two bytes hold the size of the requested block
404 * plus the range checking words, and the header word MINUS ONE.
407 union overhead *ov_next; /* when free */
408 #if MEM_ALIGNBYTES > 4
409 double strut; /* alignment problems */
412 u_char ovu_magic; /* magic number */
413 u_char ovu_index; /* bucket # */
415 u_short ovu_size; /* actual block size */
416 u_int ovu_rmagic; /* range magic number */
419 #define ov_magic ovu.ovu_magic
420 #define ov_index ovu.ovu_index
421 #define ov_size ovu.ovu_size
422 #define ov_rmagic ovu.ovu_rmagic
425 #define MAGIC 0xff /* magic # on accounting info */
426 #define RMAGIC 0x55555555 /* magic # on range info */
427 #define RMAGIC_C 0x55 /* magic # on range info */
430 # define RSLOP sizeof (u_int)
431 # ifdef TWO_POT_OPTIMIZE
432 # define MAX_SHORT_BUCKET (12 * BUCKETS_PER_POW2)
434 # define MAX_SHORT_BUCKET (13 * BUCKETS_PER_POW2)
440 #if !defined(PACK_MALLOC) && defined(BUCKETS_ROOT2)
441 # undef BUCKETS_ROOT2
445 # define BUCKET_TABLE_SHIFT 2
446 # define BUCKET_POW2_SHIFT 1
447 # define BUCKETS_PER_POW2 2
449 # define BUCKET_TABLE_SHIFT MIN_BUC_POW2
450 # define BUCKET_POW2_SHIFT 0
451 # define BUCKETS_PER_POW2 1
454 #if !defined(MEM_ALIGNBYTES) || ((MEM_ALIGNBYTES > 4) && !defined(STRICT_ALIGNMENT))
455 /* Figure out the alignment of void*. */
460 # define ALIGN_SMALL ((int)((caddr_t)&(((struct aligner*)0)->p)))
462 # define ALIGN_SMALL MEM_ALIGNBYTES
465 #define IF_ALIGN_8(yes,no) ((ALIGN_SMALL>4) ? (yes) : (no))
468 # define MAX_BUCKET_BY_TABLE 13
469 static u_short buck_size[MAX_BUCKET_BY_TABLE + 1] =
471 0, 0, 0, 0, 4, 4, 8, 12, 16, 24, 32, 48, 64, 80,
473 # define BUCKET_SIZE(i) ((i) % 2 ? buck_size[i] : (1 << ((i) >> BUCKET_POW2_SHIFT)))
474 # define BUCKET_SIZE_REAL(i) ((i) <= MAX_BUCKET_BY_TABLE \
476 : ((1 << ((i) >> BUCKET_POW2_SHIFT)) \
478 + POW2_OPTIMIZE_SURPLUS(i)))
480 # define BUCKET_SIZE(i) (1 << ((i) >> BUCKET_POW2_SHIFT))
481 # define BUCKET_SIZE_REAL(i) (BUCKET_SIZE(i) - MEM_OVERHEAD(i) + POW2_OPTIMIZE_SURPLUS(i))
486 /* In this case it is assumed that if we do sbrk() in 2K units, we
487 * will get 2K aligned arenas (at least after some initial
488 * alignment). The bucket number of the given subblock is on the start
489 * of 2K arena which contains the subblock. Several following bytes
490 * contain the magic numbers for the subblocks in the block.
492 * Sizes of chunks are powers of 2 for chunks in buckets <=
493 * MAX_PACKED, after this they are (2^n - sizeof(union overhead)) (to
494 * get alignment right).
496 * Consider an arena for 2^n with n>MAX_PACKED. We suppose that
497 * starts of all the chunks in a 2K arena are in different
498 * 2^n-byte-long chunks. If the top of the last chunk is aligned on a
499 * boundary of 2K block, this means that sizeof(union
500 * overhead)*"number of chunks" < 2^n, or sizeof(union overhead)*2K <
501 * 4^n, or n > 6 + log2(sizeof()/2)/2, since a chunk of size 2^n -
502 * overhead is used. Since this rules out n = 7 for 8 byte alignment,
503 * we specialcase allocation of the first of 16 128-byte-long chunks.
505 * Note that with the above assumption we automatically have enough
506 * place for MAGIC at the start of 2K block. Note also that we
507 * overlay union overhead over the chunk, thus the start of small chunks
508 * is immediately overwritten after freeing. */
509 # define MAX_PACKED_POW2 6
510 # define MAX_PACKED (MAX_PACKED_POW2 * BUCKETS_PER_POW2 + BUCKET_POW2_SHIFT)
511 # define MAX_POW2_ALGO ((1<<(MAX_PACKED_POW2 + 1)) - M_OVERHEAD)
512 # define TWOK_MASK ((1<<LOG_OF_MIN_ARENA) - 1)
513 # define TWOK_MASKED(x) ((u_bigint)(x) & ~TWOK_MASK)
514 # define TWOK_SHIFT(x) ((u_bigint)(x) & TWOK_MASK)
515 # define OV_INDEXp(block) ((u_char*)(TWOK_MASKED(block)))
516 # define OV_INDEX(block) (*OV_INDEXp(block))
517 # define OV_MAGIC(block,bucket) (*(OV_INDEXp(block) + \
518 (TWOK_SHIFT(block)>> \
519 (bucket>>BUCKET_POW2_SHIFT)) + \
520 (bucket >= MIN_NEEDS_SHIFT ? 1 : 0)))
521 /* A bucket can have a shift smaller than it size, we need to
522 shift its magic number so it will not overwrite index: */
523 # ifdef BUCKETS_ROOT2
524 # define MIN_NEEDS_SHIFT (7*BUCKETS_PER_POW2 - 1) /* Shift 80 greater than chunk 64. */
526 # define MIN_NEEDS_SHIFT (7*BUCKETS_PER_POW2) /* Shift 128 greater than chunk 32. */
528 # define CHUNK_SHIFT 0
530 /* Number of active buckets of given ordinal. */
531 #ifdef IGNORE_SMALL_BAD_FREE
532 #define FIRST_BUCKET_WITH_CHECK (6 * BUCKETS_PER_POW2) /* 64 */
533 # define N_BLKS(bucket) ( (bucket) < FIRST_BUCKET_WITH_CHECK \
534 ? ((1<<LOG_OF_MIN_ARENA) - 1)/BUCKET_SIZE(bucket) \
537 # define N_BLKS(bucket) n_blks[bucket]
540 static u_short n_blks[LOG_OF_MIN_ARENA * BUCKETS_PER_POW2] =
542 # if BUCKETS_PER_POW2==1
544 (MIN_BUC_POW2==2 ? 384 : 0),
545 224, 120, 62, 31, 16, 8, 4, 2
548 (MIN_BUC_POW2==2 ? 384 : 0), (MIN_BUC_POW2==2 ? 384 : 0), /* 4, 4 */
549 224, 149, 120, 80, 62, 41, 31, 25, 16, 16, 8, 8, 4, 4, 2, 2
553 /* Shift of the first bucket with the given ordinal inside 2K chunk. */
554 #ifdef IGNORE_SMALL_BAD_FREE
555 # define BLK_SHIFT(bucket) ( (bucket) < FIRST_BUCKET_WITH_CHECK \
556 ? ((1<<LOG_OF_MIN_ARENA) \
557 - BUCKET_SIZE(bucket) * N_BLKS(bucket)) \
560 # define BLK_SHIFT(bucket) blk_shift[bucket]
563 static u_short blk_shift[LOG_OF_MIN_ARENA * BUCKETS_PER_POW2] =
565 # if BUCKETS_PER_POW2==1
567 (MIN_BUC_POW2==2 ? 512 : 0),
568 256, 128, 64, 64, /* 8 to 64 */
569 16*sizeof(union overhead),
570 8*sizeof(union overhead),
571 4*sizeof(union overhead),
572 2*sizeof(union overhead),
575 (MIN_BUC_POW2==2 ? 512 : 0), (MIN_BUC_POW2==2 ? 512 : 0),
576 256, 260, 128, 128, 64, 80, 64, 48, /* 8 to 96 */
577 16*sizeof(union overhead), 16*sizeof(union overhead),
578 8*sizeof(union overhead), 8*sizeof(union overhead),
579 4*sizeof(union overhead), 4*sizeof(union overhead),
580 2*sizeof(union overhead), 2*sizeof(union overhead),
584 # define NEEDED_ALIGNMENT 0x800 /* 2k boundaries */
585 # define WANTED_ALIGNMENT 0x800 /* 2k boundaries */
587 #else /* !PACK_MALLOC */
589 # define OV_MAGIC(block,bucket) (block)->ov_magic
590 # define OV_INDEX(block) (block)->ov_index
591 # define CHUNK_SHIFT 1
592 # define MAX_PACKED -1
593 # define NEEDED_ALIGNMENT MEM_ALIGNBYTES
594 # define WANTED_ALIGNMENT 0x400 /* 1k boundaries */
596 #endif /* !PACK_MALLOC */
598 #define M_OVERHEAD (sizeof(union overhead) + RSLOP)
601 # define MEM_OVERHEAD(bucket) \
602 (bucket <= MAX_PACKED ? 0 : M_OVERHEAD)
603 # ifdef SMALL_BUCKET_VIA_TABLE
604 # define START_SHIFTS_BUCKET ((MAX_PACKED_POW2 + 1) * BUCKETS_PER_POW2)
605 # define START_SHIFT MAX_PACKED_POW2
606 # ifdef BUCKETS_ROOT2 /* Chunks of size 3*2^n. */
607 # define SIZE_TABLE_MAX 80
609 # define SIZE_TABLE_MAX 64
611 static char bucket_of[] =
613 # ifdef BUCKETS_ROOT2 /* Chunks of size 3*2^n. */
614 /* 0 to 15 in 4-byte increments. */
615 (sizeof(void*) > 4 ? 6 : 5), /* 4/8, 5-th bucket for better reports */
617 IF_ALIGN_8(8,7), 8, /* 16/12, 16 */
618 9, 9, 10, 10, /* 24, 32 */
619 11, 11, 11, 11, /* 48 */
620 12, 12, 12, 12, /* 64 */
621 13, 13, 13, 13, /* 80 */
622 13, 13, 13, 13 /* 80 */
623 # else /* !BUCKETS_ROOT2 */
624 /* 0 to 15 in 4-byte increments. */
625 (sizeof(void*) > 4 ? 3 : 2),
631 # endif /* !BUCKETS_ROOT2 */
633 # else /* !SMALL_BUCKET_VIA_TABLE */
634 # define START_SHIFTS_BUCKET MIN_BUCKET
635 # define START_SHIFT (MIN_BUC_POW2 - 1)
636 # endif /* !SMALL_BUCKET_VIA_TABLE */
637 #else /* !PACK_MALLOC */
638 # define MEM_OVERHEAD(bucket) M_OVERHEAD
639 # ifdef SMALL_BUCKET_VIA_TABLE
640 # undef SMALL_BUCKET_VIA_TABLE
642 # define START_SHIFTS_BUCKET MIN_BUCKET
643 # define START_SHIFT (MIN_BUC_POW2 - 1)
644 #endif /* !PACK_MALLOC */
647 * Big allocations are often of the size 2^n bytes. To make them a
648 * little bit better, make blocks of size 2^n+pagesize for big n.
651 #ifdef TWO_POT_OPTIMIZE
653 # ifndef PERL_PAGESIZE
654 # define PERL_PAGESIZE 4096
656 # ifndef FIRST_BIG_POW2
657 # define FIRST_BIG_POW2 15 /* 32K, 16K is used too often. */
659 # define FIRST_BIG_BLOCK (1<<FIRST_BIG_POW2)
660 /* If this value or more, check against bigger blocks. */
661 # define FIRST_BIG_BOUND (FIRST_BIG_BLOCK - M_OVERHEAD)
662 /* If less than this value, goes into 2^n-overhead-block. */
663 # define LAST_SMALL_BOUND ((FIRST_BIG_BLOCK>>1) - M_OVERHEAD)
665 # define POW2_OPTIMIZE_ADJUST(nbytes) \
666 ((nbytes >= FIRST_BIG_BOUND) ? nbytes -= PERL_PAGESIZE : 0)
667 # define POW2_OPTIMIZE_SURPLUS(bucket) \
668 ((bucket >= FIRST_BIG_POW2 * BUCKETS_PER_POW2) ? PERL_PAGESIZE : 0)
670 #else /* !TWO_POT_OPTIMIZE */
671 # define POW2_OPTIMIZE_ADJUST(nbytes)
672 # define POW2_OPTIMIZE_SURPLUS(bucket) 0
673 #endif /* !TWO_POT_OPTIMIZE */
675 #if defined(HAS_64K_LIMIT) && defined(PERL_CORE)
676 # define BARK_64K_LIMIT(what,nbytes,size) \
677 if (nbytes > 0xffff) { \
678 PerlIO_printf(PerlIO_stderr(), \
679 "%s too large: %lx\n", what, size); \
682 #else /* !HAS_64K_LIMIT || !PERL_CORE */
683 # define BARK_64K_LIMIT(what,nbytes,size)
684 #endif /* !HAS_64K_LIMIT || !PERL_CORE */
687 # define MIN_SBRK 2048
691 # define FIRST_SBRK (48*1024)
694 /* Minimal sbrk in percents of what is already alloced. */
695 #ifndef MIN_SBRK_FRAC
696 # define MIN_SBRK_FRAC 3
699 #ifndef SBRK_ALLOW_FAILURES
700 # define SBRK_ALLOW_FAILURES 3
703 #ifndef SBRK_FAILURE_PRICE
704 # define SBRK_FAILURE_PRICE 50
707 #if defined(PERL_EMERGENCY_SBRK) && defined(PERL_CORE)
710 # define BIG_SIZE (1<<16) /* 64K */
713 #ifdef I_MACH_CTHREADS
715 # define MUTEX_LOCK(m) STMT_START { if (*m) mutex_lock(*m); } STMT_END
717 # define MUTEX_UNLOCK(m) STMT_START { if (*m) mutex_unlock(*m); } STMT_END
720 static char *emergency_buffer;
721 static MEM_SIZE emergency_buffer_size;
723 static int findbucket (union overhead *freep, int srchlen);
724 static void morecore (register int bucket);
725 # if defined(DEBUGGING)
726 static void botch (char *diag, char *s);
728 static void add_to_chain (void *p, MEM_SIZE size, MEM_SIZE chip);
729 static Malloc_t emergency_sbrk (MEM_SIZE size);
730 static void* get_from_chain (MEM_SIZE size);
731 static void* get_from_bigger_buckets(int bucket, MEM_SIZE size);
732 static union overhead *getpages (int needed, int *nblksp, int bucket);
733 static int getpages_adjacent(int require);
736 emergency_sbrk(MEM_SIZE size)
738 MEM_SIZE rsize = (((size - 1)>>LOG_OF_MIN_ARENA) + 1)<<LOG_OF_MIN_ARENA;
740 if (size >= BIG_SIZE) {
741 /* Give the possibility to recover: */
743 croak("Out of memory during \"large\" request for %i bytes", size);
746 if (emergency_buffer_size >= rsize) {
747 char *old = emergency_buffer;
749 emergency_buffer_size -= rsize;
750 emergency_buffer += rsize;
754 /* First offense, give a possibility to recover by dieing. */
755 /* No malloc involved here: */
756 GV **gvp = (GV**)hv_fetch(PL_defstash, "^M", 2, 0);
762 if (emergency_buffer_size) {
763 add_to_chain(emergency_buffer, emergency_buffer_size, 0);
764 emergency_buffer_size = 0;
765 emergency_buffer = Nullch;
768 if (!gvp) gvp = (GV**)hv_fetch(PL_defstash, "\015", 1, 0);
769 if (!gvp || !(sv = GvSV(*gvp)) || !SvPOK(sv)
770 || (SvLEN(sv) < (1<<LOG_OF_MIN_ARENA) - M_OVERHEAD)) {
773 return (char *)-1; /* Now die die die... */
775 /* Got it, now detach SvPV: */
777 /* Check alignment: */
778 if (((UV)(pv - sizeof(union overhead))) & (NEEDED_ALIGNMENT - 1)) {
779 PerlIO_puts(PerlIO_stderr(),"Bad alignment of $^M!\n");
780 return (char *)-1; /* die die die */
783 emergency_buffer = pv - sizeof(union overhead);
784 emergency_buffer_size = malloced_size(pv) + M_OVERHEAD;
787 SvCUR(sv) = SvLEN(sv) = 0;
791 croak("Out of memory during request for %i bytes", size);
794 #else /* !(defined(PERL_EMERGENCY_SBRK) && defined(PERL_CORE)) */
795 # define emergency_sbrk(size) -1
796 #endif /* !(defined(PERL_EMERGENCY_SBRK) && defined(PERL_CORE)) */
799 * nextf[i] is the pointer to the next free block of size 2^i. The
800 * smallest allocatable block is 8 bytes. The overhead information
801 * precedes the data area returned to the user.
803 #define NBUCKETS (32*BUCKETS_PER_POW2 + 1)
804 static union overhead *nextf[NBUCKETS];
807 #define sbrk(a) Perl_sbrk(a)
808 Malloc_t Perl_sbrk (int size);
810 #ifdef DONT_DECLARE_STD
815 extern Malloc_t sbrk(int);
819 #ifdef DEBUGGING_MSTATS
821 * nmalloc[i] is the difference between the number of mallocs and frees
822 * for a given block size.
824 static u_int nmalloc[NBUCKETS];
825 static u_int sbrk_slack;
826 static u_int start_slack;
829 static u_int goodsbrk;
833 #define ASSERT(p,diag) if (!(p)) botch(diag,STRINGIFY(p)); else
835 botch(char *diag, char *s)
837 PerlIO_printf(PerlIO_stderr(), "assertion botched (%s?): %s\n", diag, s);
841 #define ASSERT(p, diag)
845 Perl_malloc(register size_t nbytes)
847 register union overhead *p;
849 register MEM_SIZE shiftr;
851 #if defined(DEBUGGING) || defined(RCHECK)
852 MEM_SIZE size = nbytes;
855 BARK_64K_LIMIT("Allocation",nbytes,nbytes);
857 if ((long)nbytes < 0)
858 croak("%s", "panic: malloc");
863 * Convert amount of memory requested into
864 * closest block size stored in hash buckets
865 * which satisfies request. Account for
866 * space used per block for accounting.
869 # ifdef SMALL_BUCKET_VIA_TABLE
872 else if (nbytes <= SIZE_TABLE_MAX) {
873 bucket = bucket_of[(nbytes - 1) >> BUCKET_TABLE_SHIFT];
878 if (nbytes <= MAX_POW2_ALGO) goto do_shifts;
883 POW2_OPTIMIZE_ADJUST(nbytes);
884 nbytes += M_OVERHEAD;
885 nbytes = (nbytes + 3) &~ 3;
887 shiftr = (nbytes - 1) >> START_SHIFT;
888 bucket = START_SHIFTS_BUCKET;
889 /* apart from this loop, this is O(1) */
891 bucket += BUCKETS_PER_POW2;
894 * If nothing in hash bucket right now,
895 * request more memory from the system.
897 if (nextf[bucket] == NULL)
899 if ((p = nextf[bucket]) == NULL) {
903 PerlIO_puts(PerlIO_stderr(),"Out of memory!\n");
904 WITH_THX(my_exit(1));
911 DEBUG_m(PerlIO_printf(Perl_debug_log,
912 "0x%lx: (%05lu) malloc %ld bytes\n",
913 (unsigned long)(p+1), (unsigned long)(PL_an++),
916 /* remove from linked list */
918 if (((UV)p) & (MEM_ALIGNBYTES - 1))
919 PerlIO_printf(PerlIO_stderr(), "Corrupt malloc ptr 0x%lx at 0x%lx\n",
920 (unsigned long)*((int*)p),(unsigned long)p);
922 nextf[bucket] = p->ov_next;
923 #ifdef IGNORE_SMALL_BAD_FREE
924 if (bucket >= FIRST_BUCKET_WITH_CHECK)
926 OV_MAGIC(p, bucket) = MAGIC;
928 OV_INDEX(p) = bucket;
932 * Record allocated size of block and
933 * bound space with magic numbers.
935 p->ov_rmagic = RMAGIC;
936 if (bucket <= MAX_SHORT_BUCKET) {
939 nbytes = size + M_OVERHEAD;
940 p->ov_size = nbytes - 1;
941 if ((i = nbytes & 3)) {
944 *((char *)((caddr_t)p + nbytes - RSLOP + i)) = RMAGIC_C;
946 nbytes = (nbytes + 3) &~ 3;
947 *((u_int *)((caddr_t)p + nbytes - RSLOP)) = RMAGIC;
951 return ((Malloc_t)(p + CHUNK_SHIFT));
954 static char *last_sbrk_top;
955 static char *last_op; /* This arena can be easily extended. */
956 static int sbrked_remains;
957 static int sbrk_good = SBRK_ALLOW_FAILURES * SBRK_FAILURE_PRICE;
959 #ifdef DEBUGGING_MSTATS
963 struct chunk_chain_s {
964 struct chunk_chain_s *next;
967 static struct chunk_chain_s *chunk_chain;
969 static char max_bucket;
971 /* Cutoff a piece of one of the chunks in the chain. Prefer smaller chunk. */
973 get_from_chain(MEM_SIZE size)
975 struct chunk_chain_s *elt = chunk_chain, **oldp = &chunk_chain;
976 struct chunk_chain_s **oldgoodp = NULL;
977 long min_remain = LONG_MAX;
980 if (elt->size >= size) {
981 long remains = elt->size - size;
982 if (remains >= 0 && remains < min_remain) {
984 min_remain = remains;
990 oldp = &( elt->next );
993 if (!oldgoodp) return NULL;
995 void *ret = *oldgoodp;
996 struct chunk_chain_s *next = (*oldgoodp)->next;
998 *oldgoodp = (struct chunk_chain_s *)((char*)ret + size);
999 (*oldgoodp)->size = min_remain;
1000 (*oldgoodp)->next = next;
1003 void *ret = *oldgoodp;
1004 *oldgoodp = (*oldgoodp)->next;
1011 add_to_chain(void *p, MEM_SIZE size, MEM_SIZE chip)
1013 struct chunk_chain_s *next = chunk_chain;
1014 char *cp = (char*)p;
1017 chunk_chain = (struct chunk_chain_s *)cp;
1018 chunk_chain->size = size - chip;
1019 chunk_chain->next = next;
1024 get_from_bigger_buckets(int bucket, MEM_SIZE size)
1027 static int bucketprice[NBUCKETS];
1028 while (bucket <= max_bucket) {
1029 /* We postpone stealing from bigger buckets until we want it
1031 if (nextf[bucket] && bucketprice[bucket]++ >= price) {
1033 void *ret = (void*)(nextf[bucket] - 1 + CHUNK_SHIFT);
1034 bucketprice[bucket] = 0;
1035 if (((char*)nextf[bucket]) - M_OVERHEAD == last_op) {
1036 last_op = NULL; /* Disable optimization */
1038 nextf[bucket] = nextf[bucket]->ov_next;
1039 #ifdef DEBUGGING_MSTATS
1041 start_slack -= M_OVERHEAD;
1043 add_to_chain(ret, (BUCKET_SIZE(bucket) +
1044 POW2_OPTIMIZE_SURPLUS(bucket)),
1053 static union overhead *
1054 getpages(int needed, int *nblksp, int bucket)
1056 /* Need to do (possibly expensive) system call. Try to
1057 optimize it for rare calling. */
1058 MEM_SIZE require = needed - sbrked_remains;
1060 union overhead *ovp;
1063 if (sbrk_good > 0) {
1064 if (!last_sbrk_top && require < FIRST_SBRK)
1065 require = FIRST_SBRK;
1066 else if (require < MIN_SBRK) require = MIN_SBRK;
1068 if (require < goodsbrk * MIN_SBRK_FRAC / 100)
1069 require = goodsbrk * MIN_SBRK_FRAC / 100;
1070 require = ((require - 1 + MIN_SBRK) / MIN_SBRK) * MIN_SBRK;
1077 DEBUG_m(PerlIO_printf(Perl_debug_log,
1078 "sbrk(%ld) for %ld-byte-long arena\n",
1079 (long)require, (long) needed));
1080 cp = (char *)sbrk(require);
1081 #ifdef DEBUGGING_MSTATS
1084 if (cp == last_sbrk_top) {
1085 /* Common case, anything is fine. */
1087 ovp = (union overhead *) (cp - sbrked_remains);
1088 last_op = cp - sbrked_remains;
1089 sbrked_remains = require - (needed - sbrked_remains);
1090 } else if (cp == (char *)-1) { /* no more room! */
1091 ovp = (union overhead *)emergency_sbrk(needed);
1092 if (ovp == (union overhead *)-1)
1094 if (((char*)ovp) > last_op) { /* Cannot happen with current emergency_sbrk() */
1098 } else { /* Non-continuous or first sbrk(). */
1099 long add = sbrked_remains;
1102 if (sbrked_remains) { /* Put rest into chain, we
1103 cannot use it right now. */
1104 add_to_chain((void*)(last_sbrk_top - sbrked_remains),
1108 /* Second, check alignment. */
1111 #if !defined(atarist) && !defined(__MINT__) /* on the atari we dont have to worry about this */
1112 # ifndef I286 /* The sbrk(0) call on the I286 always returns the next segment */
1113 /* WANTED_ALIGNMENT may be more than NEEDED_ALIGNMENT, but this may
1114 improve performance of memory access. */
1115 if ((UV)cp & (WANTED_ALIGNMENT - 1)) { /* Not aligned. */
1116 slack = WANTED_ALIGNMENT - ((UV)cp & (WANTED_ALIGNMENT - 1));
1120 #endif /* !atarist && !MINT */
1123 DEBUG_m(PerlIO_printf(Perl_debug_log,
1124 "sbrk(%ld) to fix non-continuous/off-page sbrk:\n\t%ld for alignement,\t%ld were assumed to come from the tail of the previous sbrk\n",
1125 (long)add, (long) slack,
1126 (long) sbrked_remains));
1127 newcp = (char *)sbrk(add);
1128 #if defined(DEBUGGING_MSTATS)
1132 if (newcp != cp + require) {
1133 /* Too bad: even rounding sbrk() is not continuous.*/
1134 DEBUG_m(PerlIO_printf(Perl_debug_log,
1135 "failed to fix bad sbrk()\n"));
1139 fatalcroak("panic: Off-page sbrk\n");
1142 if (sbrked_remains) {
1144 #if defined(DEBUGGING_MSTATS)
1145 sbrk_slack += require;
1148 DEBUG_m(PerlIO_printf(Perl_debug_log,
1149 "straight sbrk(%ld)\n",
1151 cp = (char *)sbrk(require);
1152 #ifdef DEBUGGING_MSTATS
1155 if (cp == (char *)-1)
1158 sbrk_good = -1; /* Disable optimization!
1159 Continue with not-aligned... */
1162 require += sbrked_remains;
1166 if (last_sbrk_top) {
1167 sbrk_good -= SBRK_FAILURE_PRICE;
1170 ovp = (union overhead *) cp;
1172 * Round up to minimum allocation size boundary
1173 * and deduct from block count to reflect.
1176 # if NEEDED_ALIGNMENT > MEM_ALIGNBYTES
1177 if ((UV)ovp & (NEEDED_ALIGNMENT - 1))
1178 fatalcroak("Misalignment of sbrk()\n");
1181 #ifndef I286 /* Again, this should always be ok on an 80286 */
1182 if ((UV)ovp & (MEM_ALIGNBYTES - 1)) {
1183 DEBUG_m(PerlIO_printf(Perl_debug_log,
1184 "fixing sbrk(): %d bytes off machine alignement\n",
1185 (int)((UV)ovp & (MEM_ALIGNBYTES - 1))));
1186 ovp = (union overhead *)(((UV)ovp + MEM_ALIGNBYTES) &
1187 (MEM_ALIGNBYTES - 1));
1189 # if defined(DEBUGGING_MSTATS)
1190 /* This is only approx. if TWO_POT_OPTIMIZE: */
1191 sbrk_slack += (1 << (bucket >> BUCKET_POW2_SHIFT));
1195 ; /* Finish `else' */
1196 sbrked_remains = require - needed;
1199 last_sbrk_top = cp + require;
1200 #ifdef DEBUGGING_MSTATS
1201 goodsbrk += require;
1207 getpages_adjacent(int require)
1209 if (require <= sbrked_remains) {
1210 sbrked_remains -= require;
1214 require -= sbrked_remains;
1215 /* We do not try to optimize sbrks here, we go for place. */
1216 cp = (char*) sbrk(require);
1217 #ifdef DEBUGGING_MSTATS
1219 goodsbrk += require;
1221 if (cp == last_sbrk_top) {
1223 last_sbrk_top = cp + require;
1225 if (cp == (char*)-1) { /* Out of memory */
1226 #ifdef DEBUGGING_MSTATS
1227 goodsbrk -= require;
1231 /* Report the failure: */
1233 add_to_chain((void*)(last_sbrk_top - sbrked_remains),
1235 add_to_chain((void*)cp, require, 0);
1236 sbrk_good -= SBRK_FAILURE_PRICE;
1248 * Allocate more memory to the indicated bucket.
1251 morecore(register int bucket)
1253 register union overhead *ovp;
1254 register int rnu; /* 2^rnu bytes will be requested */
1255 int nblks; /* become nblks blocks of the desired size */
1256 register MEM_SIZE siz, needed;
1260 if (bucket == sizeof(MEM_SIZE)*8*BUCKETS_PER_POW2) {
1262 croak("%s", "Out of memory during ridiculously large request");
1264 if (bucket > max_bucket)
1265 max_bucket = bucket;
1267 rnu = ( (bucket <= (LOG_OF_MIN_ARENA << BUCKET_POW2_SHIFT))
1269 : (bucket >> BUCKET_POW2_SHIFT) );
1270 /* This may be overwritten later: */
1271 nblks = 1 << (rnu - (bucket >> BUCKET_POW2_SHIFT)); /* how many blocks to get */
1272 needed = ((MEM_SIZE)1 << rnu) + POW2_OPTIMIZE_SURPLUS(bucket);
1273 if (nextf[rnu << BUCKET_POW2_SHIFT]) { /* 2048b bucket. */
1274 ovp = nextf[rnu << BUCKET_POW2_SHIFT] - 1 + CHUNK_SHIFT;
1275 nextf[rnu << BUCKET_POW2_SHIFT]
1276 = nextf[rnu << BUCKET_POW2_SHIFT]->ov_next;
1277 #ifdef DEBUGGING_MSTATS
1278 nmalloc[rnu << BUCKET_POW2_SHIFT]--;
1279 start_slack -= M_OVERHEAD;
1281 DEBUG_m(PerlIO_printf(Perl_debug_log,
1282 "stealing %ld bytes from %ld arena\n",
1283 (long) needed, (long) rnu << BUCKET_POW2_SHIFT));
1284 } else if (chunk_chain
1285 && (ovp = (union overhead*) get_from_chain(needed))) {
1286 DEBUG_m(PerlIO_printf(Perl_debug_log,
1287 "stealing %ld bytes from chain\n",
1289 } else if ( (ovp = (union overhead*)
1290 get_from_bigger_buckets((rnu << BUCKET_POW2_SHIFT) + 1,
1292 DEBUG_m(PerlIO_printf(Perl_debug_log,
1293 "stealing %ld bytes from bigger buckets\n",
1295 } else if (needed <= sbrked_remains) {
1296 ovp = (union overhead *)(last_sbrk_top - sbrked_remains);
1297 sbrked_remains -= needed;
1298 last_op = (char*)ovp;
1300 ovp = getpages(needed, &nblks, bucket);
1306 * Add new memory allocated to that on
1307 * free list for this hash bucket.
1309 siz = BUCKET_SIZE(bucket);
1311 *(u_char*)ovp = bucket; /* Fill index. */
1312 if (bucket <= MAX_PACKED) {
1313 ovp = (union overhead *) ((char*)ovp + BLK_SHIFT(bucket));
1314 nblks = N_BLKS(bucket);
1315 # ifdef DEBUGGING_MSTATS
1316 start_slack += BLK_SHIFT(bucket);
1318 } else if (bucket < LOG_OF_MIN_ARENA * BUCKETS_PER_POW2) {
1319 ovp = (union overhead *) ((char*)ovp + BLK_SHIFT(bucket));
1320 siz -= sizeof(union overhead);
1321 } else ovp++; /* One chunk per block. */
1322 #endif /* PACK_MALLOC */
1323 nextf[bucket] = ovp;
1324 #ifdef DEBUGGING_MSTATS
1325 nmalloc[bucket] += nblks;
1326 if (bucket > MAX_PACKED) {
1327 start_slack += M_OVERHEAD * nblks;
1330 while (--nblks > 0) {
1331 ovp->ov_next = (union overhead *)((caddr_t)ovp + siz);
1332 ovp = (union overhead *)((caddr_t)ovp + siz);
1334 /* Not all sbrks return zeroed memory.*/
1335 ovp->ov_next = (union overhead *)NULL;
1337 if (bucket == 7*BUCKETS_PER_POW2) { /* Special case, explanation is above. */
1338 union overhead *n_op = nextf[7*BUCKETS_PER_POW2]->ov_next;
1339 nextf[7*BUCKETS_PER_POW2] =
1340 (union overhead *)((caddr_t)nextf[7*BUCKETS_PER_POW2]
1341 - sizeof(union overhead));
1342 nextf[7*BUCKETS_PER_POW2]->ov_next = n_op;
1344 #endif /* !PACK_MALLOC */
1348 Perl_mfree(void *mp)
1350 register MEM_SIZE size;
1351 register union overhead *ovp;
1352 char *cp = (char*)mp;
1357 DEBUG_m(PerlIO_printf(Perl_debug_log,
1358 "0x%lx: (%05lu) free\n",
1359 (unsigned long)cp, (unsigned long)(PL_an++)));
1363 ovp = (union overhead *)((caddr_t)cp
1364 - sizeof (union overhead) * CHUNK_SHIFT);
1366 bucket = OV_INDEX(ovp);
1368 #ifdef IGNORE_SMALL_BAD_FREE
1369 if ((bucket >= FIRST_BUCKET_WITH_CHECK)
1370 && (OV_MAGIC(ovp, bucket) != MAGIC))
1372 if (OV_MAGIC(ovp, bucket) != MAGIC)
1375 static int bad_free_warn = -1;
1376 if (bad_free_warn == -1) {
1377 char *pbf = PerlEnv_getenv("PERL_BADFREE");
1378 bad_free_warn = (pbf) ? atoi(pbf) : 1;
1383 warn("%s free() ignored",
1384 ovp->ov_rmagic == RMAGIC - 1 ? "Duplicate" : "Bad");
1386 warn("%s", "Bad free() ignored");
1388 return; /* sanity */
1392 ASSERT(ovp->ov_rmagic == RMAGIC, "chunk's head overwrite");
1393 if (OV_INDEX(ovp) <= MAX_SHORT_BUCKET) {
1395 MEM_SIZE nbytes = ovp->ov_size + 1;
1397 if ((i = nbytes & 3)) {
1400 ASSERT(*((char *)((caddr_t)ovp + nbytes - RSLOP + i))
1401 == RMAGIC_C, "chunk's tail overwrite");
1404 nbytes = (nbytes + 3) &~ 3;
1405 ASSERT(*(u_int *)((caddr_t)ovp + nbytes - RSLOP) == RMAGIC, "chunk's tail overwrite");
1407 ovp->ov_rmagic = RMAGIC - 1;
1409 ASSERT(OV_INDEX(ovp) < NBUCKETS, "chunk's head overwrite");
1410 size = OV_INDEX(ovp);
1411 ovp->ov_next = nextf[size];
1417 * When a program attempts "storage compaction" as mentioned in the
1418 * old malloc man page, it realloc's an already freed block. Usually
1419 * this is the last block it freed; occasionally it might be farther
1420 * back. We have to search all the free lists for the block in order
1421 * to determine its bucket: 1st we make one pass thru the lists
1422 * checking only the first block in each; if that fails we search
1423 * ``reall_srchlen'' blocks in each list for a match (the variable
1424 * is extern so the caller can modify it). If that fails we just copy
1425 * however many bytes was given to realloc() and hope it's not huge.
1427 #define reall_srchlen 4 /* 4 should be plenty, -1 =>'s whole list */
1430 Perl_realloc(void *mp, size_t nbytes)
1432 register MEM_SIZE onb;
1433 union overhead *ovp;
1436 register int bucket;
1437 int was_alloced = 0, incr;
1438 char *cp = (char*)mp;
1440 #if defined(DEBUGGING) || !defined(PERL_CORE)
1441 MEM_SIZE size = nbytes;
1443 if ((long)nbytes < 0)
1444 croak("%s", "panic: realloc");
1447 BARK_64K_LIMIT("Reallocation",nbytes,size);
1449 return Perl_malloc(nbytes);
1452 ovp = (union overhead *)((caddr_t)cp
1453 - sizeof (union overhead) * CHUNK_SHIFT);
1454 bucket = OV_INDEX(ovp);
1455 #ifdef IGNORE_SMALL_BAD_FREE
1456 if ((bucket < FIRST_BUCKET_WITH_CHECK)
1457 || (OV_MAGIC(ovp, bucket) == MAGIC))
1459 if (OV_MAGIC(ovp, bucket) == MAGIC)
1465 * Already free, doing "compaction".
1467 * Search for the old block of memory on the
1468 * free list. First, check the most common
1469 * case (last element free'd), then (this failing)
1470 * the last ``reall_srchlen'' items free'd.
1471 * If all lookups fail, then assume the size of
1472 * the memory block being realloc'd is the
1473 * smallest possible.
1475 if ((bucket = findbucket(ovp, 1)) < 0 &&
1476 (bucket = findbucket(ovp, reall_srchlen)) < 0)
1479 onb = BUCKET_SIZE_REAL(bucket);
1481 * avoid the copy if same size block.
1482 * We are not agressive with boundary cases. Note that it might
1483 * (for a small number of cases) give false negative if
1484 * both new size and old one are in the bucket for
1485 * FIRST_BIG_POW2, but the new one is near the lower end.
1487 * We do not try to go to 1.5 times smaller bucket so far.
1489 if (nbytes > onb) incr = 1;
1491 #ifdef DO_NOT_TRY_HARDER_WHEN_SHRINKING
1492 if ( /* This is a little bit pessimal if PACK_MALLOC: */
1493 nbytes > ( (onb >> 1) - M_OVERHEAD )
1494 # ifdef TWO_POT_OPTIMIZE
1495 || (bucket == FIRST_BIG_POW2 && nbytes >= LAST_SMALL_BOUND )
1498 #else /* !DO_NOT_TRY_HARDER_WHEN_SHRINKING */
1499 prev_bucket = ( (bucket > MAX_PACKED + 1)
1500 ? bucket - BUCKETS_PER_POW2
1502 if (nbytes > BUCKET_SIZE_REAL(prev_bucket))
1503 #endif /* !DO_NOT_TRY_HARDER_WHEN_SHRINKING */
1508 #ifdef STRESS_REALLOC
1509 || 1 /* always do it the hard way */
1512 else if (incr == 0) {
1516 * Record new allocated size of block and
1517 * bound space with magic numbers.
1519 if (OV_INDEX(ovp) <= MAX_SHORT_BUCKET) {
1520 int i, nb = ovp->ov_size + 1;
1525 ASSERT(*((char *)((caddr_t)ovp + nb - RSLOP + i)) == RMAGIC_C, "chunk's tail overwrite");
1529 ASSERT(*(u_int *)((caddr_t)ovp + nb - RSLOP) == RMAGIC, "chunk's tail overwrite");
1531 * Convert amount of memory requested into
1532 * closest block size stored in hash buckets
1533 * which satisfies request. Account for
1534 * space used per block for accounting.
1536 nbytes += M_OVERHEAD;
1537 ovp->ov_size = nbytes - 1;
1538 if ((i = nbytes & 3)) {
1541 *((char *)((caddr_t)ovp + nbytes - RSLOP + i))
1544 nbytes = (nbytes + 3) &~ 3;
1545 *((u_int *)((caddr_t)ovp + nbytes - RSLOP)) = RMAGIC;
1550 DEBUG_m(PerlIO_printf(Perl_debug_log,
1551 "0x%lx: (%05lu) realloc %ld bytes inplace\n",
1552 (unsigned long)res,(unsigned long)(PL_an++),
1554 } else if (incr == 1 && (cp - M_OVERHEAD == last_op)
1555 && (onb > (1 << LOG_OF_MIN_ARENA))) {
1556 MEM_SIZE require, newarena = nbytes, pow;
1559 POW2_OPTIMIZE_ADJUST(newarena);
1560 newarena = newarena + M_OVERHEAD;
1561 /* newarena = (newarena + 3) &~ 3; */
1562 shiftr = (newarena - 1) >> LOG_OF_MIN_ARENA;
1563 pow = LOG_OF_MIN_ARENA + 1;
1564 /* apart from this loop, this is O(1) */
1565 while (shiftr >>= 1)
1567 newarena = (1 << pow) + POW2_OPTIMIZE_SURPLUS(pow * BUCKETS_PER_POW2);
1568 require = newarena - onb - M_OVERHEAD;
1570 if (getpages_adjacent(require)) {
1571 #ifdef DEBUGGING_MSTATS
1573 nmalloc[pow * BUCKETS_PER_POW2]++;
1575 *(cp - M_OVERHEAD) = pow * BUCKETS_PER_POW2; /* Fill index. */
1582 DEBUG_m(PerlIO_printf(Perl_debug_log,
1583 "0x%lx: (%05lu) realloc %ld bytes the hard way\n",
1584 (unsigned long)cp,(unsigned long)(PL_an++),
1586 if ((res = (char*)Perl_malloc(nbytes)) == NULL)
1588 if (cp != res) /* common optimization */
1589 Copy(cp, res, (MEM_SIZE)(nbytes<onb?nbytes:onb), char);
1593 return ((Malloc_t)res);
1597 * Search ``srchlen'' elements of each free list for a block whose
1598 * header starts at ``freep''. If srchlen is -1 search the whole list.
1599 * Return bucket number, or -1 if not found.
1602 findbucket(union overhead *freep, int srchlen)
1604 register union overhead *p;
1607 for (i = 0; i < NBUCKETS; i++) {
1609 for (p = nextf[i]; p && j != srchlen; p = p->ov_next) {
1619 Perl_calloc(register size_t elements, register size_t size)
1621 long sz = elements * size;
1622 Malloc_t p = Perl_malloc(sz);
1625 memset((void*)p, 0, sz);
1631 Perl_malloced_size(void *p)
1633 union overhead *ovp = (union overhead *)
1634 ((caddr_t)p - sizeof (union overhead) * CHUNK_SHIFT);
1635 int bucket = OV_INDEX(ovp);
1637 /* The caller wants to have a complete control over the chunk,
1638 disable the memory checking inside the chunk. */
1639 if (bucket <= MAX_SHORT_BUCKET) {
1640 MEM_SIZE size = BUCKET_SIZE_REAL(bucket);
1641 ovp->ov_size = size + M_OVERHEAD - 1;
1642 *((u_int *)((caddr_t)ovp + size + M_OVERHEAD - RSLOP)) = RMAGIC;
1645 return BUCKET_SIZE_REAL(bucket);
1648 # ifdef BUCKETS_ROOT2
1649 # define MIN_EVEN_REPORT 6
1651 # define MIN_EVEN_REPORT MIN_BUCKET
1654 * mstats - print out statistics about malloc
1656 * Prints two lines of numbers, one showing the length of the free list
1657 * for each size category, the second showing the number of mallocs -
1658 * frees for each size category.
1661 Perl_dump_mstats(pTHX_ char *s)
1663 #ifdef DEBUGGING_MSTATS
1665 register union overhead *p;
1666 int topbucket=0, topbucket_ev=0, topbucket_odd=0, totfree=0, total=0;
1667 u_int nfree[NBUCKETS];
1668 int total_chain = 0;
1669 struct chunk_chain_s* nextchain = chunk_chain;
1671 for (i = MIN_BUCKET ; i < NBUCKETS; i++) {
1672 for (j = 0, p = nextf[i]; p; p = p->ov_next, j++)
1675 totfree += nfree[i] * BUCKET_SIZE_REAL(i);
1676 total += nmalloc[i] * BUCKET_SIZE_REAL(i);
1678 i % 2 ? (topbucket_odd = i) : (topbucket_ev = i);
1683 PerlIO_printf(PerlIO_stderr(),
1684 "Memory allocation statistics %s (buckets %ld(%ld)..%ld(%ld)\n",
1686 (long)BUCKET_SIZE_REAL(MIN_BUCKET),
1687 (long)BUCKET_SIZE(MIN_BUCKET),
1688 (long)BUCKET_SIZE_REAL(topbucket), (long)BUCKET_SIZE(topbucket));
1689 PerlIO_printf(PerlIO_stderr(), "%8d free:", totfree);
1690 for (i = MIN_EVEN_REPORT; i <= topbucket; i += BUCKETS_PER_POW2) {
1691 PerlIO_printf(PerlIO_stderr(),
1692 ((i < 8*BUCKETS_PER_POW2 || i == 10*BUCKETS_PER_POW2)
1694 : ((i < 12*BUCKETS_PER_POW2) ? " %3d" : " %d")),
1697 #ifdef BUCKETS_ROOT2
1698 PerlIO_printf(PerlIO_stderr(), "\n\t ");
1699 for (i = MIN_BUCKET + 1; i <= topbucket_odd; i += BUCKETS_PER_POW2) {
1700 PerlIO_printf(PerlIO_stderr(),
1701 ((i < 8*BUCKETS_PER_POW2 || i == 10*BUCKETS_PER_POW2)
1703 : ((i < 12*BUCKETS_PER_POW2) ? " %3d" : " %d")),
1707 PerlIO_printf(PerlIO_stderr(), "\n%8d used:", total - totfree);
1708 for (i = MIN_EVEN_REPORT; i <= topbucket; i += BUCKETS_PER_POW2) {
1709 PerlIO_printf(PerlIO_stderr(),
1710 ((i < 8*BUCKETS_PER_POW2 || i == 10*BUCKETS_PER_POW2)
1712 : ((i < 12*BUCKETS_PER_POW2) ? " %3d" : " %d")),
1713 nmalloc[i] - nfree[i]);
1715 #ifdef BUCKETS_ROOT2
1716 PerlIO_printf(PerlIO_stderr(), "\n\t ");
1717 for (i = MIN_BUCKET + 1; i <= topbucket_odd; i += BUCKETS_PER_POW2) {
1718 PerlIO_printf(PerlIO_stderr(),
1719 ((i < 8*BUCKETS_PER_POW2 || i == 10*BUCKETS_PER_POW2)
1721 : ((i < 12*BUCKETS_PER_POW2) ? " %3d" : " %d")),
1722 nmalloc[i] - nfree[i]);
1726 total_chain += nextchain->size;
1727 nextchain = nextchain->next;
1729 PerlIO_printf(PerlIO_stderr(), "\nTotal sbrk(): %d/%d:%d. Odd ends: pad+heads+chain+tail: %d+%d+%d+%d.\n",
1730 goodsbrk + sbrk_slack, sbrks, sbrk_good, sbrk_slack,
1731 start_slack, total_chain, sbrked_remains);
1732 #endif /* DEBUGGING_MSTATS */
1736 #ifdef USE_PERL_SBRK
1738 # if defined(__MACHTEN_PPC__) || defined(NeXT) || defined(__NeXT__)
1739 # define PERL_SBRK_VIA_MALLOC
1741 * MachTen's malloc() returns a buffer aligned on a two-byte boundary.
1742 * While this is adequate, it may slow down access to longer data
1743 * types by forcing multiple memory accesses. It also causes
1744 * complaints when RCHECK is in force. So we allocate six bytes
1745 * more than we need to, and return an address rounded up to an
1746 * eight-byte boundary.
1748 * 980701 Dominic Dunlop <domo@computer.org>
1750 # define SYSTEM_ALLOC_ALIGNMENT 2
1753 # ifdef PERL_SBRK_VIA_MALLOC
1755 /* it may seem schizophrenic to use perl's malloc and let it call system */
1756 /* malloc, the reason for that is only the 3.2 version of the OS that had */
1757 /* frequent core dumps within nxzonefreenolock. This sbrk routine put an */
1758 /* end to the cores */
1760 # ifndef SYSTEM_ALLOC
1761 # define SYSTEM_ALLOC(a) malloc(a)
1763 # ifndef SYSTEM_ALLOC_ALIGNMENT
1764 # define SYSTEM_ALLOC_ALIGNMENT MEM_ALIGNBYTES
1767 # endif /* PERL_SBRK_VIA_MALLOC */
1769 static IV Perl_sbrk_oldchunk;
1770 static long Perl_sbrk_oldsize;
1772 # define PERLSBRK_32_K (1<<15)
1773 # define PERLSBRK_64_K (1<<16)
1781 if (!size) return 0;
1783 reqsize = size; /* just for the DEBUG_m statement */
1786 size = (size + 0x7ff) & ~0x7ff;
1788 if (size <= Perl_sbrk_oldsize) {
1789 got = Perl_sbrk_oldchunk;
1790 Perl_sbrk_oldchunk += size;
1791 Perl_sbrk_oldsize -= size;
1793 if (size >= PERLSBRK_32_K) {
1796 size = PERLSBRK_64_K;
1799 # if NEEDED_ALIGNMENT > SYSTEM_ALLOC_ALIGNMENT
1800 size += NEEDED_ALIGNMENT - SYSTEM_ALLOC_ALIGNMENT;
1802 got = (IV)SYSTEM_ALLOC(size);
1803 # if NEEDED_ALIGNMENT > SYSTEM_ALLOC_ALIGNMENT
1804 got = (got + NEEDED_ALIGNMENT - 1) & ~(NEEDED_ALIGNMENT - 1);
1807 /* Chunk is small, register the rest for future allocs. */
1808 Perl_sbrk_oldchunk = got + reqsize;
1809 Perl_sbrk_oldsize = size - reqsize;
1813 DEBUG_m(PerlIO_printf(Perl_debug_log, "sbrk malloc size %ld (reqsize %ld), left size %ld, give addr 0x%lx\n",
1814 size, reqsize, Perl_sbrk_oldsize, got));
1819 #endif /* ! defined USE_PERL_SBRK */