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
287 # ifndef PERL_GET_INTERP
288 # define PERL_GET_INTERP PL_curinterp
293 # define MUTEX_LOCK(l)
297 # define MUTEX_UNLOCK(l)
301 # define MALLOC_LOCK MUTEX_LOCK_NOCONTEXT(&PL_malloc_mutex)
304 #ifndef MALLOC_UNLOCK
305 # define MALLOC_UNLOCK MUTEX_UNLOCK_NOCONTEXT(&PL_malloc_mutex)
308 # ifndef fatalcroak /* make depend */
309 # define fatalcroak(mess) (write(2, (mess), strlen(mess)), exit(2))
314 # define DEBUG_m(a) if (PERL_GET_INTERP && PL_debug & 128) a
320 * The memory is broken into "blocks" which occupy multiples of 2K (and
321 * generally speaking, have size "close" to a power of 2). The addresses
322 * of such *unused* blocks are kept in nextf[i] with big enough i. (nextf
323 * is an array of linked lists.) (Addresses of used blocks are not known.)
325 * Moreover, since the algorithm may try to "bite" smaller blocks of out
326 * of unused bigger ones, there are also regions of "irregular" size,
327 * managed separately, by a linked list chunk_chain.
329 * The third type of storage is the sbrk()ed-but-not-yet-used space, its
330 * end and size are kept in last_sbrk_top and sbrked_remains.
332 * Growing blocks "in place":
333 * ~~~~~~~~~~~~~~~~~~~~~~~~~
334 * The address of the block with the greatest address is kept in last_op
335 * (if not known, last_op is 0). If it is known that the memory above
336 * last_op is not continuous, or contains a chunk from chunk_chain,
337 * last_op is set to 0.
339 * The chunk with address last_op may be grown by expanding into
340 * sbrk()ed-but-not-yet-used space, or trying to sbrk() more continuous
343 * Management of last_op:
344 * ~~~~~~~~~~~~~~~~~~~~~
346 * free() never changes the boundaries of blocks, so is not relevant.
348 * The only way realloc() may change the boundaries of blocks is if it
349 * grows a block "in place". However, in the case of success such a
350 * chunk is automatically last_op, and it remains last_op. In the case
351 * of failure getpages_adjacent() clears last_op.
353 * malloc() may change blocks by calling morecore() only.
355 * morecore() may create new blocks by:
356 * a) biting pieces from chunk_chain (cannot create one above last_op);
357 * b) biting a piece from an unused block (if block was last_op, this
358 * may create a chunk from chain above last_op, thus last_op is
359 * invalidated in such a case).
360 * c) biting of sbrk()ed-but-not-yet-used space. This creates
361 * a block which is last_op.
362 * d) Allocating new pages by calling getpages();
364 * getpages() creates a new block. It marks last_op at the bottom of
365 * the chunk of memory it returns.
367 * Active pages footprint:
368 * ~~~~~~~~~~~~~~~~~~~~~~
369 * Note that we do not need to traverse the lists in nextf[i], just take
370 * the first element of this list. However, we *need* to traverse the
371 * list in chunk_chain, but most the time it should be a very short one,
372 * so we do not step on a lot of pages we are not going to use.
376 * get_from_bigger_buckets(): forget to increment price => Quite
380 /* I don't much care whether these are defined in sys/types.h--LAW */
382 #define u_char unsigned char
383 #define u_int unsigned int
386 # define u_bigint UV /* Needs to eat *void. */
388 # define u_bigint unsigned long /* Needs to eat *void. */
391 #define u_short unsigned short
393 /* 286 and atarist like big chunks, which gives too much overhead. */
394 #if (defined(RCHECK) || defined(I286) || defined(atarist) || defined(__MINT__)) && defined(PACK_MALLOC)
399 * The description below is applicable if PACK_MALLOC is not defined.
401 * The overhead on a block is at least 4 bytes. When free, this space
402 * contains a pointer to the next free block, and the bottom two bits must
403 * be zero. When in use, the first byte is set to MAGIC, and the second
404 * byte is the size index. The remaining bytes are for alignment.
405 * If range checking is enabled and the size of the block fits
406 * in two bytes, then the top two bytes hold the size of the requested block
407 * plus the range checking words, and the header word MINUS ONE.
410 union overhead *ov_next; /* when free */
411 #if MEM_ALIGNBYTES > 4
412 double strut; /* alignment problems */
415 u_char ovu_magic; /* magic number */
416 u_char ovu_index; /* bucket # */
418 u_short ovu_size; /* actual block size */
419 u_int ovu_rmagic; /* range magic number */
422 #define ov_magic ovu.ovu_magic
423 #define ov_index ovu.ovu_index
424 #define ov_size ovu.ovu_size
425 #define ov_rmagic ovu.ovu_rmagic
428 #define MAGIC 0xff /* magic # on accounting info */
429 #define RMAGIC 0x55555555 /* magic # on range info */
430 #define RMAGIC_C 0x55 /* magic # on range info */
433 # define RSLOP sizeof (u_int)
434 # ifdef TWO_POT_OPTIMIZE
435 # define MAX_SHORT_BUCKET (12 * BUCKETS_PER_POW2)
437 # define MAX_SHORT_BUCKET (13 * BUCKETS_PER_POW2)
443 #if !defined(PACK_MALLOC) && defined(BUCKETS_ROOT2)
444 # undef BUCKETS_ROOT2
448 # define BUCKET_TABLE_SHIFT 2
449 # define BUCKET_POW2_SHIFT 1
450 # define BUCKETS_PER_POW2 2
452 # define BUCKET_TABLE_SHIFT MIN_BUC_POW2
453 # define BUCKET_POW2_SHIFT 0
454 # define BUCKETS_PER_POW2 1
457 #if !defined(MEM_ALIGNBYTES) || ((MEM_ALIGNBYTES > 4) && !defined(STRICT_ALIGNMENT))
458 /* Figure out the alignment of void*. */
463 # define ALIGN_SMALL ((int)((caddr_t)&(((struct aligner*)0)->p)))
465 # define ALIGN_SMALL MEM_ALIGNBYTES
468 #define IF_ALIGN_8(yes,no) ((ALIGN_SMALL>4) ? (yes) : (no))
471 # define MAX_BUCKET_BY_TABLE 13
472 static u_short buck_size[MAX_BUCKET_BY_TABLE + 1] =
474 0, 0, 0, 0, 4, 4, 8, 12, 16, 24, 32, 48, 64, 80,
476 # define BUCKET_SIZE(i) ((i) % 2 ? buck_size[i] : (1 << ((i) >> BUCKET_POW2_SHIFT)))
477 # define BUCKET_SIZE_REAL(i) ((i) <= MAX_BUCKET_BY_TABLE \
479 : ((1 << ((i) >> BUCKET_POW2_SHIFT)) \
481 + POW2_OPTIMIZE_SURPLUS(i)))
483 # define BUCKET_SIZE(i) (1 << ((i) >> BUCKET_POW2_SHIFT))
484 # define BUCKET_SIZE_REAL(i) (BUCKET_SIZE(i) - MEM_OVERHEAD(i) + POW2_OPTIMIZE_SURPLUS(i))
489 /* In this case it is assumed that if we do sbrk() in 2K units, we
490 * will get 2K aligned arenas (at least after some initial
491 * alignment). The bucket number of the given subblock is on the start
492 * of 2K arena which contains the subblock. Several following bytes
493 * contain the magic numbers for the subblocks in the block.
495 * Sizes of chunks are powers of 2 for chunks in buckets <=
496 * MAX_PACKED, after this they are (2^n - sizeof(union overhead)) (to
497 * get alignment right).
499 * Consider an arena for 2^n with n>MAX_PACKED. We suppose that
500 * starts of all the chunks in a 2K arena are in different
501 * 2^n-byte-long chunks. If the top of the last chunk is aligned on a
502 * boundary of 2K block, this means that sizeof(union
503 * overhead)*"number of chunks" < 2^n, or sizeof(union overhead)*2K <
504 * 4^n, or n > 6 + log2(sizeof()/2)/2, since a chunk of size 2^n -
505 * overhead is used. Since this rules out n = 7 for 8 byte alignment,
506 * we specialcase allocation of the first of 16 128-byte-long chunks.
508 * Note that with the above assumption we automatically have enough
509 * place for MAGIC at the start of 2K block. Note also that we
510 * overlay union overhead over the chunk, thus the start of small chunks
511 * is immediately overwritten after freeing. */
512 # define MAX_PACKED_POW2 6
513 # define MAX_PACKED (MAX_PACKED_POW2 * BUCKETS_PER_POW2 + BUCKET_POW2_SHIFT)
514 # define MAX_POW2_ALGO ((1<<(MAX_PACKED_POW2 + 1)) - M_OVERHEAD)
515 # define TWOK_MASK ((1<<LOG_OF_MIN_ARENA) - 1)
516 # define TWOK_MASKED(x) ((u_bigint)(x) & ~TWOK_MASK)
517 # define TWOK_SHIFT(x) ((u_bigint)(x) & TWOK_MASK)
518 # define OV_INDEXp(block) ((u_char*)(TWOK_MASKED(block)))
519 # define OV_INDEX(block) (*OV_INDEXp(block))
520 # define OV_MAGIC(block,bucket) (*(OV_INDEXp(block) + \
521 (TWOK_SHIFT(block)>> \
522 (bucket>>BUCKET_POW2_SHIFT)) + \
523 (bucket >= MIN_NEEDS_SHIFT ? 1 : 0)))
524 /* A bucket can have a shift smaller than it size, we need to
525 shift its magic number so it will not overwrite index: */
526 # ifdef BUCKETS_ROOT2
527 # define MIN_NEEDS_SHIFT (7*BUCKETS_PER_POW2 - 1) /* Shift 80 greater than chunk 64. */
529 # define MIN_NEEDS_SHIFT (7*BUCKETS_PER_POW2) /* Shift 128 greater than chunk 32. */
531 # define CHUNK_SHIFT 0
533 /* Number of active buckets of given ordinal. */
534 #ifdef IGNORE_SMALL_BAD_FREE
535 #define FIRST_BUCKET_WITH_CHECK (6 * BUCKETS_PER_POW2) /* 64 */
536 # define N_BLKS(bucket) ( (bucket) < FIRST_BUCKET_WITH_CHECK \
537 ? ((1<<LOG_OF_MIN_ARENA) - 1)/BUCKET_SIZE(bucket) \
540 # define N_BLKS(bucket) n_blks[bucket]
543 static u_short n_blks[LOG_OF_MIN_ARENA * BUCKETS_PER_POW2] =
545 # if BUCKETS_PER_POW2==1
547 (MIN_BUC_POW2==2 ? 384 : 0),
548 224, 120, 62, 31, 16, 8, 4, 2
551 (MIN_BUC_POW2==2 ? 384 : 0), (MIN_BUC_POW2==2 ? 384 : 0), /* 4, 4 */
552 224, 149, 120, 80, 62, 41, 31, 25, 16, 16, 8, 8, 4, 4, 2, 2
556 /* Shift of the first bucket with the given ordinal inside 2K chunk. */
557 #ifdef IGNORE_SMALL_BAD_FREE
558 # define BLK_SHIFT(bucket) ( (bucket) < FIRST_BUCKET_WITH_CHECK \
559 ? ((1<<LOG_OF_MIN_ARENA) \
560 - BUCKET_SIZE(bucket) * N_BLKS(bucket)) \
563 # define BLK_SHIFT(bucket) blk_shift[bucket]
566 static u_short blk_shift[LOG_OF_MIN_ARENA * BUCKETS_PER_POW2] =
568 # if BUCKETS_PER_POW2==1
570 (MIN_BUC_POW2==2 ? 512 : 0),
571 256, 128, 64, 64, /* 8 to 64 */
572 16*sizeof(union overhead),
573 8*sizeof(union overhead),
574 4*sizeof(union overhead),
575 2*sizeof(union overhead),
578 (MIN_BUC_POW2==2 ? 512 : 0), (MIN_BUC_POW2==2 ? 512 : 0),
579 256, 260, 128, 128, 64, 80, 64, 48, /* 8 to 96 */
580 16*sizeof(union overhead), 16*sizeof(union overhead),
581 8*sizeof(union overhead), 8*sizeof(union overhead),
582 4*sizeof(union overhead), 4*sizeof(union overhead),
583 2*sizeof(union overhead), 2*sizeof(union overhead),
587 # define NEEDED_ALIGNMENT 0x800 /* 2k boundaries */
588 # define WANTED_ALIGNMENT 0x800 /* 2k boundaries */
590 #else /* !PACK_MALLOC */
592 # define OV_MAGIC(block,bucket) (block)->ov_magic
593 # define OV_INDEX(block) (block)->ov_index
594 # define CHUNK_SHIFT 1
595 # define MAX_PACKED -1
596 # define NEEDED_ALIGNMENT MEM_ALIGNBYTES
597 # define WANTED_ALIGNMENT 0x400 /* 1k boundaries */
599 #endif /* !PACK_MALLOC */
601 #define M_OVERHEAD (sizeof(union overhead) + RSLOP)
604 # define MEM_OVERHEAD(bucket) \
605 (bucket <= MAX_PACKED ? 0 : M_OVERHEAD)
606 # ifdef SMALL_BUCKET_VIA_TABLE
607 # define START_SHIFTS_BUCKET ((MAX_PACKED_POW2 + 1) * BUCKETS_PER_POW2)
608 # define START_SHIFT MAX_PACKED_POW2
609 # ifdef BUCKETS_ROOT2 /* Chunks of size 3*2^n. */
610 # define SIZE_TABLE_MAX 80
612 # define SIZE_TABLE_MAX 64
614 static char bucket_of[] =
616 # ifdef BUCKETS_ROOT2 /* Chunks of size 3*2^n. */
617 /* 0 to 15 in 4-byte increments. */
618 (sizeof(void*) > 4 ? 6 : 5), /* 4/8, 5-th bucket for better reports */
620 IF_ALIGN_8(8,7), 8, /* 16/12, 16 */
621 9, 9, 10, 10, /* 24, 32 */
622 11, 11, 11, 11, /* 48 */
623 12, 12, 12, 12, /* 64 */
624 13, 13, 13, 13, /* 80 */
625 13, 13, 13, 13 /* 80 */
626 # else /* !BUCKETS_ROOT2 */
627 /* 0 to 15 in 4-byte increments. */
628 (sizeof(void*) > 4 ? 3 : 2),
634 # endif /* !BUCKETS_ROOT2 */
636 # else /* !SMALL_BUCKET_VIA_TABLE */
637 # define START_SHIFTS_BUCKET MIN_BUCKET
638 # define START_SHIFT (MIN_BUC_POW2 - 1)
639 # endif /* !SMALL_BUCKET_VIA_TABLE */
640 #else /* !PACK_MALLOC */
641 # define MEM_OVERHEAD(bucket) M_OVERHEAD
642 # ifdef SMALL_BUCKET_VIA_TABLE
643 # undef SMALL_BUCKET_VIA_TABLE
645 # define START_SHIFTS_BUCKET MIN_BUCKET
646 # define START_SHIFT (MIN_BUC_POW2 - 1)
647 #endif /* !PACK_MALLOC */
650 * Big allocations are often of the size 2^n bytes. To make them a
651 * little bit better, make blocks of size 2^n+pagesize for big n.
654 #ifdef TWO_POT_OPTIMIZE
656 # ifndef PERL_PAGESIZE
657 # define PERL_PAGESIZE 4096
659 # ifndef FIRST_BIG_POW2
660 # define FIRST_BIG_POW2 15 /* 32K, 16K is used too often. */
662 # define FIRST_BIG_BLOCK (1<<FIRST_BIG_POW2)
663 /* If this value or more, check against bigger blocks. */
664 # define FIRST_BIG_BOUND (FIRST_BIG_BLOCK - M_OVERHEAD)
665 /* If less than this value, goes into 2^n-overhead-block. */
666 # define LAST_SMALL_BOUND ((FIRST_BIG_BLOCK>>1) - M_OVERHEAD)
668 # define POW2_OPTIMIZE_ADJUST(nbytes) \
669 ((nbytes >= FIRST_BIG_BOUND) ? nbytes -= PERL_PAGESIZE : 0)
670 # define POW2_OPTIMIZE_SURPLUS(bucket) \
671 ((bucket >= FIRST_BIG_POW2 * BUCKETS_PER_POW2) ? PERL_PAGESIZE : 0)
673 #else /* !TWO_POT_OPTIMIZE */
674 # define POW2_OPTIMIZE_ADJUST(nbytes)
675 # define POW2_OPTIMIZE_SURPLUS(bucket) 0
676 #endif /* !TWO_POT_OPTIMIZE */
678 #if defined(HAS_64K_LIMIT) && defined(PERL_CORE)
679 # define BARK_64K_LIMIT(what,nbytes,size) \
680 if (nbytes > 0xffff) { \
681 PerlIO_printf(PerlIO_stderr(), \
682 "%s too large: %lx\n", what, size); \
685 #else /* !HAS_64K_LIMIT || !PERL_CORE */
686 # define BARK_64K_LIMIT(what,nbytes,size)
687 #endif /* !HAS_64K_LIMIT || !PERL_CORE */
690 # define MIN_SBRK 2048
694 # define FIRST_SBRK (48*1024)
697 /* Minimal sbrk in percents of what is already alloced. */
698 #ifndef MIN_SBRK_FRAC
699 # define MIN_SBRK_FRAC 3
702 #ifndef SBRK_ALLOW_FAILURES
703 # define SBRK_ALLOW_FAILURES 3
706 #ifndef SBRK_FAILURE_PRICE
707 # define SBRK_FAILURE_PRICE 50
710 #if defined(PERL_EMERGENCY_SBRK) && defined(PERL_CORE)
713 # define BIG_SIZE (1<<16) /* 64K */
716 #ifdef I_MACH_CTHREADS
718 # define MUTEX_LOCK(m) STMT_START { if (*m) mutex_lock(*m); } STMT_END
720 # define MUTEX_UNLOCK(m) STMT_START { if (*m) mutex_unlock(*m); } STMT_END
723 static char *emergency_buffer;
724 static MEM_SIZE emergency_buffer_size;
726 static int findbucket (union overhead *freep, int srchlen);
727 static void morecore (register int bucket);
728 # if defined(DEBUGGING)
729 static void botch (char *diag, char *s);
731 static void add_to_chain (void *p, MEM_SIZE size, MEM_SIZE chip);
732 static Malloc_t emergency_sbrk (MEM_SIZE size);
733 static void* get_from_chain (MEM_SIZE size);
734 static void* get_from_bigger_buckets(int bucket, MEM_SIZE size);
735 static union overhead *getpages (int needed, int *nblksp, int bucket);
736 static int getpages_adjacent(int require);
739 emergency_sbrk(MEM_SIZE size)
741 MEM_SIZE rsize = (((size - 1)>>LOG_OF_MIN_ARENA) + 1)<<LOG_OF_MIN_ARENA;
743 if (size >= BIG_SIZE) {
744 /* Give the possibility to recover: */
746 croak("Out of memory during \"large\" request for %i bytes", size);
749 if (emergency_buffer_size >= rsize) {
750 char *old = emergency_buffer;
752 emergency_buffer_size -= rsize;
753 emergency_buffer += rsize;
757 /* First offense, give a possibility to recover by dieing. */
758 /* No malloc involved here: */
759 GV **gvp = (GV**)hv_fetch(PL_defstash, "^M", 2, 0);
765 if (emergency_buffer_size) {
766 add_to_chain(emergency_buffer, emergency_buffer_size, 0);
767 emergency_buffer_size = 0;
768 emergency_buffer = Nullch;
771 if (!gvp) gvp = (GV**)hv_fetch(PL_defstash, "\015", 1, 0);
772 if (!gvp || !(sv = GvSV(*gvp)) || !SvPOK(sv)
773 || (SvLEN(sv) < (1<<LOG_OF_MIN_ARENA) - M_OVERHEAD)) {
776 return (char *)-1; /* Now die die die... */
778 /* Got it, now detach SvPV: */
780 /* Check alignment: */
781 if (((UV)(pv - sizeof(union overhead))) & (NEEDED_ALIGNMENT - 1)) {
782 PerlIO_puts(PerlIO_stderr(),"Bad alignment of $^M!\n");
783 return (char *)-1; /* die die die */
786 emergency_buffer = pv - sizeof(union overhead);
787 emergency_buffer_size = malloced_size(pv) + M_OVERHEAD;
790 SvCUR(sv) = SvLEN(sv) = 0;
794 croak("Out of memory during request for %i bytes", size);
797 #else /* !(defined(PERL_EMERGENCY_SBRK) && defined(PERL_CORE)) */
798 # define emergency_sbrk(size) -1
799 #endif /* !(defined(PERL_EMERGENCY_SBRK) && defined(PERL_CORE)) */
802 * nextf[i] is the pointer to the next free block of size 2^i. The
803 * smallest allocatable block is 8 bytes. The overhead information
804 * precedes the data area returned to the user.
806 #define NBUCKETS (32*BUCKETS_PER_POW2 + 1)
807 static union overhead *nextf[NBUCKETS];
810 #define sbrk(a) Perl_sbrk(a)
811 Malloc_t Perl_sbrk (int size);
813 #ifdef DONT_DECLARE_STD
818 extern Malloc_t sbrk(int);
822 #ifdef DEBUGGING_MSTATS
824 * nmalloc[i] is the difference between the number of mallocs and frees
825 * for a given block size.
827 static u_int nmalloc[NBUCKETS];
828 static u_int sbrk_slack;
829 static u_int start_slack;
832 static u_int goodsbrk;
836 #define ASSERT(p,diag) if (!(p)) botch(diag,STRINGIFY(p)); else
838 botch(char *diag, char *s)
840 PerlIO_printf(PerlIO_stderr(), "assertion botched (%s?): %s\n", diag, s);
844 #define ASSERT(p, diag)
848 Perl_malloc(register size_t nbytes)
850 register union overhead *p;
852 register MEM_SIZE shiftr;
854 #if defined(DEBUGGING) || defined(RCHECK)
855 MEM_SIZE size = nbytes;
858 BARK_64K_LIMIT("Allocation",nbytes,nbytes);
860 if ((long)nbytes < 0)
861 croak("%s", "panic: malloc");
866 * Convert amount of memory requested into
867 * closest block size stored in hash buckets
868 * which satisfies request. Account for
869 * space used per block for accounting.
872 # ifdef SMALL_BUCKET_VIA_TABLE
875 else if (nbytes <= SIZE_TABLE_MAX) {
876 bucket = bucket_of[(nbytes - 1) >> BUCKET_TABLE_SHIFT];
881 if (nbytes <= MAX_POW2_ALGO) goto do_shifts;
886 POW2_OPTIMIZE_ADJUST(nbytes);
887 nbytes += M_OVERHEAD;
888 nbytes = (nbytes + 3) &~ 3;
890 shiftr = (nbytes - 1) >> START_SHIFT;
891 bucket = START_SHIFTS_BUCKET;
892 /* apart from this loop, this is O(1) */
894 bucket += BUCKETS_PER_POW2;
897 * If nothing in hash bucket right now,
898 * request more memory from the system.
900 if (nextf[bucket] == NULL)
902 if ((p = nextf[bucket]) == NULL) {
906 PerlIO_puts(PerlIO_stderr(),"Out of memory!\n");
907 WITH_THX(my_exit(1));
914 DEBUG_m(PerlIO_printf(Perl_debug_log,
915 "0x%lx: (%05lu) malloc %ld bytes\n",
916 (unsigned long)(p+1), (unsigned long)(PL_an++),
919 /* remove from linked list */
921 if (((UV)p) & (MEM_ALIGNBYTES - 1))
922 PerlIO_printf(PerlIO_stderr(), "Corrupt malloc ptr 0x%lx at 0x%lx\n",
923 (unsigned long)*((int*)p),(unsigned long)p);
925 nextf[bucket] = p->ov_next;
926 #ifdef IGNORE_SMALL_BAD_FREE
927 if (bucket >= FIRST_BUCKET_WITH_CHECK)
929 OV_MAGIC(p, bucket) = MAGIC;
931 OV_INDEX(p) = bucket;
935 * Record allocated size of block and
936 * bound space with magic numbers.
938 p->ov_rmagic = RMAGIC;
939 if (bucket <= MAX_SHORT_BUCKET) {
942 nbytes = size + M_OVERHEAD;
943 p->ov_size = nbytes - 1;
944 if ((i = nbytes & 3)) {
947 *((char *)((caddr_t)p + nbytes - RSLOP + i)) = RMAGIC_C;
949 nbytes = (nbytes + 3) &~ 3;
950 *((u_int *)((caddr_t)p + nbytes - RSLOP)) = RMAGIC;
954 return ((Malloc_t)(p + CHUNK_SHIFT));
957 static char *last_sbrk_top;
958 static char *last_op; /* This arena can be easily extended. */
959 static int sbrked_remains;
960 static int sbrk_good = SBRK_ALLOW_FAILURES * SBRK_FAILURE_PRICE;
962 #ifdef DEBUGGING_MSTATS
966 struct chunk_chain_s {
967 struct chunk_chain_s *next;
970 static struct chunk_chain_s *chunk_chain;
972 static char max_bucket;
974 /* Cutoff a piece of one of the chunks in the chain. Prefer smaller chunk. */
976 get_from_chain(MEM_SIZE size)
978 struct chunk_chain_s *elt = chunk_chain, **oldp = &chunk_chain;
979 struct chunk_chain_s **oldgoodp = NULL;
980 long min_remain = LONG_MAX;
983 if (elt->size >= size) {
984 long remains = elt->size - size;
985 if (remains >= 0 && remains < min_remain) {
987 min_remain = remains;
993 oldp = &( elt->next );
996 if (!oldgoodp) return NULL;
998 void *ret = *oldgoodp;
999 struct chunk_chain_s *next = (*oldgoodp)->next;
1001 *oldgoodp = (struct chunk_chain_s *)((char*)ret + size);
1002 (*oldgoodp)->size = min_remain;
1003 (*oldgoodp)->next = next;
1006 void *ret = *oldgoodp;
1007 *oldgoodp = (*oldgoodp)->next;
1014 add_to_chain(void *p, MEM_SIZE size, MEM_SIZE chip)
1016 struct chunk_chain_s *next = chunk_chain;
1017 char *cp = (char*)p;
1020 chunk_chain = (struct chunk_chain_s *)cp;
1021 chunk_chain->size = size - chip;
1022 chunk_chain->next = next;
1027 get_from_bigger_buckets(int bucket, MEM_SIZE size)
1030 static int bucketprice[NBUCKETS];
1031 while (bucket <= max_bucket) {
1032 /* We postpone stealing from bigger buckets until we want it
1034 if (nextf[bucket] && bucketprice[bucket]++ >= price) {
1036 void *ret = (void*)(nextf[bucket] - 1 + CHUNK_SHIFT);
1037 bucketprice[bucket] = 0;
1038 if (((char*)nextf[bucket]) - M_OVERHEAD == last_op) {
1039 last_op = NULL; /* Disable optimization */
1041 nextf[bucket] = nextf[bucket]->ov_next;
1042 #ifdef DEBUGGING_MSTATS
1044 start_slack -= M_OVERHEAD;
1046 add_to_chain(ret, (BUCKET_SIZE(bucket) +
1047 POW2_OPTIMIZE_SURPLUS(bucket)),
1056 static union overhead *
1057 getpages(int needed, int *nblksp, int bucket)
1059 /* Need to do (possibly expensive) system call. Try to
1060 optimize it for rare calling. */
1061 MEM_SIZE require = needed - sbrked_remains;
1063 union overhead *ovp;
1066 if (sbrk_good > 0) {
1067 if (!last_sbrk_top && require < FIRST_SBRK)
1068 require = FIRST_SBRK;
1069 else if (require < MIN_SBRK) require = MIN_SBRK;
1071 if (require < goodsbrk * MIN_SBRK_FRAC / 100)
1072 require = goodsbrk * MIN_SBRK_FRAC / 100;
1073 require = ((require - 1 + MIN_SBRK) / MIN_SBRK) * MIN_SBRK;
1080 DEBUG_m(PerlIO_printf(Perl_debug_log,
1081 "sbrk(%ld) for %ld-byte-long arena\n",
1082 (long)require, (long) needed));
1083 cp = (char *)sbrk(require);
1084 #ifdef DEBUGGING_MSTATS
1087 if (cp == last_sbrk_top) {
1088 /* Common case, anything is fine. */
1090 ovp = (union overhead *) (cp - sbrked_remains);
1091 last_op = cp - sbrked_remains;
1092 sbrked_remains = require - (needed - sbrked_remains);
1093 } else if (cp == (char *)-1) { /* no more room! */
1094 ovp = (union overhead *)emergency_sbrk(needed);
1095 if (ovp == (union overhead *)-1)
1097 if (((char*)ovp) > last_op) { /* Cannot happen with current emergency_sbrk() */
1101 } else { /* Non-continuous or first sbrk(). */
1102 long add = sbrked_remains;
1105 if (sbrked_remains) { /* Put rest into chain, we
1106 cannot use it right now. */
1107 add_to_chain((void*)(last_sbrk_top - sbrked_remains),
1111 /* Second, check alignment. */
1114 #if !defined(atarist) && !defined(__MINT__) /* on the atari we dont have to worry about this */
1115 # ifndef I286 /* The sbrk(0) call on the I286 always returns the next segment */
1116 /* WANTED_ALIGNMENT may be more than NEEDED_ALIGNMENT, but this may
1117 improve performance of memory access. */
1118 if ((UV)cp & (WANTED_ALIGNMENT - 1)) { /* Not aligned. */
1119 slack = WANTED_ALIGNMENT - ((UV)cp & (WANTED_ALIGNMENT - 1));
1123 #endif /* !atarist && !MINT */
1126 DEBUG_m(PerlIO_printf(Perl_debug_log,
1127 "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",
1128 (long)add, (long) slack,
1129 (long) sbrked_remains));
1130 newcp = (char *)sbrk(add);
1131 #if defined(DEBUGGING_MSTATS)
1135 if (newcp != cp + require) {
1136 /* Too bad: even rounding sbrk() is not continuous.*/
1137 DEBUG_m(PerlIO_printf(Perl_debug_log,
1138 "failed to fix bad sbrk()\n"));
1142 fatalcroak("panic: Off-page sbrk\n");
1145 if (sbrked_remains) {
1147 #if defined(DEBUGGING_MSTATS)
1148 sbrk_slack += require;
1151 DEBUG_m(PerlIO_printf(Perl_debug_log,
1152 "straight sbrk(%ld)\n",
1154 cp = (char *)sbrk(require);
1155 #ifdef DEBUGGING_MSTATS
1158 if (cp == (char *)-1)
1161 sbrk_good = -1; /* Disable optimization!
1162 Continue with not-aligned... */
1165 require += sbrked_remains;
1169 if (last_sbrk_top) {
1170 sbrk_good -= SBRK_FAILURE_PRICE;
1173 ovp = (union overhead *) cp;
1175 * Round up to minimum allocation size boundary
1176 * and deduct from block count to reflect.
1179 # if NEEDED_ALIGNMENT > MEM_ALIGNBYTES
1180 if ((UV)ovp & (NEEDED_ALIGNMENT - 1))
1181 fatalcroak("Misalignment of sbrk()\n");
1184 #ifndef I286 /* Again, this should always be ok on an 80286 */
1185 if ((UV)ovp & (MEM_ALIGNBYTES - 1)) {
1186 DEBUG_m(PerlIO_printf(Perl_debug_log,
1187 "fixing sbrk(): %d bytes off machine alignement\n",
1188 (int)((UV)ovp & (MEM_ALIGNBYTES - 1))));
1189 ovp = (union overhead *)(((UV)ovp + MEM_ALIGNBYTES) &
1190 (MEM_ALIGNBYTES - 1));
1192 # if defined(DEBUGGING_MSTATS)
1193 /* This is only approx. if TWO_POT_OPTIMIZE: */
1194 sbrk_slack += (1 << (bucket >> BUCKET_POW2_SHIFT));
1198 ; /* Finish `else' */
1199 sbrked_remains = require - needed;
1202 last_sbrk_top = cp + require;
1203 #ifdef DEBUGGING_MSTATS
1204 goodsbrk += require;
1210 getpages_adjacent(int require)
1212 if (require <= sbrked_remains) {
1213 sbrked_remains -= require;
1217 require -= sbrked_remains;
1218 /* We do not try to optimize sbrks here, we go for place. */
1219 cp = (char*) sbrk(require);
1220 #ifdef DEBUGGING_MSTATS
1222 goodsbrk += require;
1224 if (cp == last_sbrk_top) {
1226 last_sbrk_top = cp + require;
1228 if (cp == (char*)-1) { /* Out of memory */
1229 #ifdef DEBUGGING_MSTATS
1230 goodsbrk -= require;
1234 /* Report the failure: */
1236 add_to_chain((void*)(last_sbrk_top - sbrked_remains),
1238 add_to_chain((void*)cp, require, 0);
1239 sbrk_good -= SBRK_FAILURE_PRICE;
1251 * Allocate more memory to the indicated bucket.
1254 morecore(register int bucket)
1256 register union overhead *ovp;
1257 register int rnu; /* 2^rnu bytes will be requested */
1258 int nblks; /* become nblks blocks of the desired size */
1259 register MEM_SIZE siz, needed;
1263 if (bucket == sizeof(MEM_SIZE)*8*BUCKETS_PER_POW2) {
1265 croak("%s", "Out of memory during ridiculously large request");
1267 if (bucket > max_bucket)
1268 max_bucket = bucket;
1270 rnu = ( (bucket <= (LOG_OF_MIN_ARENA << BUCKET_POW2_SHIFT))
1272 : (bucket >> BUCKET_POW2_SHIFT) );
1273 /* This may be overwritten later: */
1274 nblks = 1 << (rnu - (bucket >> BUCKET_POW2_SHIFT)); /* how many blocks to get */
1275 needed = ((MEM_SIZE)1 << rnu) + POW2_OPTIMIZE_SURPLUS(bucket);
1276 if (nextf[rnu << BUCKET_POW2_SHIFT]) { /* 2048b bucket. */
1277 ovp = nextf[rnu << BUCKET_POW2_SHIFT] - 1 + CHUNK_SHIFT;
1278 nextf[rnu << BUCKET_POW2_SHIFT]
1279 = nextf[rnu << BUCKET_POW2_SHIFT]->ov_next;
1280 #ifdef DEBUGGING_MSTATS
1281 nmalloc[rnu << BUCKET_POW2_SHIFT]--;
1282 start_slack -= M_OVERHEAD;
1284 DEBUG_m(PerlIO_printf(Perl_debug_log,
1285 "stealing %ld bytes from %ld arena\n",
1286 (long) needed, (long) rnu << BUCKET_POW2_SHIFT));
1287 } else if (chunk_chain
1288 && (ovp = (union overhead*) get_from_chain(needed))) {
1289 DEBUG_m(PerlIO_printf(Perl_debug_log,
1290 "stealing %ld bytes from chain\n",
1292 } else if ( (ovp = (union overhead*)
1293 get_from_bigger_buckets((rnu << BUCKET_POW2_SHIFT) + 1,
1295 DEBUG_m(PerlIO_printf(Perl_debug_log,
1296 "stealing %ld bytes from bigger buckets\n",
1298 } else if (needed <= sbrked_remains) {
1299 ovp = (union overhead *)(last_sbrk_top - sbrked_remains);
1300 sbrked_remains -= needed;
1301 last_op = (char*)ovp;
1303 ovp = getpages(needed, &nblks, bucket);
1309 * Add new memory allocated to that on
1310 * free list for this hash bucket.
1312 siz = BUCKET_SIZE(bucket);
1314 *(u_char*)ovp = bucket; /* Fill index. */
1315 if (bucket <= MAX_PACKED) {
1316 ovp = (union overhead *) ((char*)ovp + BLK_SHIFT(bucket));
1317 nblks = N_BLKS(bucket);
1318 # ifdef DEBUGGING_MSTATS
1319 start_slack += BLK_SHIFT(bucket);
1321 } else if (bucket < LOG_OF_MIN_ARENA * BUCKETS_PER_POW2) {
1322 ovp = (union overhead *) ((char*)ovp + BLK_SHIFT(bucket));
1323 siz -= sizeof(union overhead);
1324 } else ovp++; /* One chunk per block. */
1325 #endif /* PACK_MALLOC */
1326 nextf[bucket] = ovp;
1327 #ifdef DEBUGGING_MSTATS
1328 nmalloc[bucket] += nblks;
1329 if (bucket > MAX_PACKED) {
1330 start_slack += M_OVERHEAD * nblks;
1333 while (--nblks > 0) {
1334 ovp->ov_next = (union overhead *)((caddr_t)ovp + siz);
1335 ovp = (union overhead *)((caddr_t)ovp + siz);
1337 /* Not all sbrks return zeroed memory.*/
1338 ovp->ov_next = (union overhead *)NULL;
1340 if (bucket == 7*BUCKETS_PER_POW2) { /* Special case, explanation is above. */
1341 union overhead *n_op = nextf[7*BUCKETS_PER_POW2]->ov_next;
1342 nextf[7*BUCKETS_PER_POW2] =
1343 (union overhead *)((caddr_t)nextf[7*BUCKETS_PER_POW2]
1344 - sizeof(union overhead));
1345 nextf[7*BUCKETS_PER_POW2]->ov_next = n_op;
1347 #endif /* !PACK_MALLOC */
1351 Perl_mfree(void *mp)
1353 register MEM_SIZE size;
1354 register union overhead *ovp;
1355 char *cp = (char*)mp;
1360 DEBUG_m(PerlIO_printf(Perl_debug_log,
1361 "0x%lx: (%05lu) free\n",
1362 (unsigned long)cp, (unsigned long)(PL_an++)));
1366 ovp = (union overhead *)((caddr_t)cp
1367 - sizeof (union overhead) * CHUNK_SHIFT);
1369 bucket = OV_INDEX(ovp);
1371 #ifdef IGNORE_SMALL_BAD_FREE
1372 if ((bucket >= FIRST_BUCKET_WITH_CHECK)
1373 && (OV_MAGIC(ovp, bucket) != MAGIC))
1375 if (OV_MAGIC(ovp, bucket) != MAGIC)
1378 static int bad_free_warn = -1;
1379 if (bad_free_warn == -1) {
1380 char *pbf = PerlEnv_getenv("PERL_BADFREE");
1381 bad_free_warn = (pbf) ? atoi(pbf) : 1;
1386 warn("%s free() ignored",
1387 ovp->ov_rmagic == RMAGIC - 1 ? "Duplicate" : "Bad");
1389 warn("%s", "Bad free() ignored");
1391 return; /* sanity */
1395 ASSERT(ovp->ov_rmagic == RMAGIC, "chunk's head overwrite");
1396 if (OV_INDEX(ovp) <= MAX_SHORT_BUCKET) {
1398 MEM_SIZE nbytes = ovp->ov_size + 1;
1400 if ((i = nbytes & 3)) {
1403 ASSERT(*((char *)((caddr_t)ovp + nbytes - RSLOP + i))
1404 == RMAGIC_C, "chunk's tail overwrite");
1407 nbytes = (nbytes + 3) &~ 3;
1408 ASSERT(*(u_int *)((caddr_t)ovp + nbytes - RSLOP) == RMAGIC, "chunk's tail overwrite");
1410 ovp->ov_rmagic = RMAGIC - 1;
1412 ASSERT(OV_INDEX(ovp) < NBUCKETS, "chunk's head overwrite");
1413 size = OV_INDEX(ovp);
1414 ovp->ov_next = nextf[size];
1420 * When a program attempts "storage compaction" as mentioned in the
1421 * old malloc man page, it realloc's an already freed block. Usually
1422 * this is the last block it freed; occasionally it might be farther
1423 * back. We have to search all the free lists for the block in order
1424 * to determine its bucket: 1st we make one pass thru the lists
1425 * checking only the first block in each; if that fails we search
1426 * ``reall_srchlen'' blocks in each list for a match (the variable
1427 * is extern so the caller can modify it). If that fails we just copy
1428 * however many bytes was given to realloc() and hope it's not huge.
1430 #define reall_srchlen 4 /* 4 should be plenty, -1 =>'s whole list */
1433 Perl_realloc(void *mp, size_t nbytes)
1435 register MEM_SIZE onb;
1436 union overhead *ovp;
1439 register int bucket;
1440 int was_alloced = 0, incr;
1441 char *cp = (char*)mp;
1443 #if defined(DEBUGGING) || !defined(PERL_CORE)
1444 MEM_SIZE size = nbytes;
1446 if ((long)nbytes < 0)
1447 croak("%s", "panic: realloc");
1450 BARK_64K_LIMIT("Reallocation",nbytes,size);
1452 return Perl_malloc(nbytes);
1455 ovp = (union overhead *)((caddr_t)cp
1456 - sizeof (union overhead) * CHUNK_SHIFT);
1457 bucket = OV_INDEX(ovp);
1458 #ifdef IGNORE_SMALL_BAD_FREE
1459 if ((bucket < FIRST_BUCKET_WITH_CHECK)
1460 || (OV_MAGIC(ovp, bucket) == MAGIC))
1462 if (OV_MAGIC(ovp, bucket) == MAGIC)
1468 * Already free, doing "compaction".
1470 * Search for the old block of memory on the
1471 * free list. First, check the most common
1472 * case (last element free'd), then (this failing)
1473 * the last ``reall_srchlen'' items free'd.
1474 * If all lookups fail, then assume the size of
1475 * the memory block being realloc'd is the
1476 * smallest possible.
1478 if ((bucket = findbucket(ovp, 1)) < 0 &&
1479 (bucket = findbucket(ovp, reall_srchlen)) < 0)
1482 onb = BUCKET_SIZE_REAL(bucket);
1484 * avoid the copy if same size block.
1485 * We are not agressive with boundary cases. Note that it might
1486 * (for a small number of cases) give false negative if
1487 * both new size and old one are in the bucket for
1488 * FIRST_BIG_POW2, but the new one is near the lower end.
1490 * We do not try to go to 1.5 times smaller bucket so far.
1492 if (nbytes > onb) incr = 1;
1494 #ifdef DO_NOT_TRY_HARDER_WHEN_SHRINKING
1495 if ( /* This is a little bit pessimal if PACK_MALLOC: */
1496 nbytes > ( (onb >> 1) - M_OVERHEAD )
1497 # ifdef TWO_POT_OPTIMIZE
1498 || (bucket == FIRST_BIG_POW2 && nbytes >= LAST_SMALL_BOUND )
1501 #else /* !DO_NOT_TRY_HARDER_WHEN_SHRINKING */
1502 prev_bucket = ( (bucket > MAX_PACKED + 1)
1503 ? bucket - BUCKETS_PER_POW2
1505 if (nbytes > BUCKET_SIZE_REAL(prev_bucket))
1506 #endif /* !DO_NOT_TRY_HARDER_WHEN_SHRINKING */
1511 #ifdef STRESS_REALLOC
1512 || 1 /* always do it the hard way */
1515 else if (incr == 0) {
1519 * Record new allocated size of block and
1520 * bound space with magic numbers.
1522 if (OV_INDEX(ovp) <= MAX_SHORT_BUCKET) {
1523 int i, nb = ovp->ov_size + 1;
1528 ASSERT(*((char *)((caddr_t)ovp + nb - RSLOP + i)) == RMAGIC_C, "chunk's tail overwrite");
1532 ASSERT(*(u_int *)((caddr_t)ovp + nb - RSLOP) == RMAGIC, "chunk's tail overwrite");
1534 * Convert amount of memory requested into
1535 * closest block size stored in hash buckets
1536 * which satisfies request. Account for
1537 * space used per block for accounting.
1539 nbytes += M_OVERHEAD;
1540 ovp->ov_size = nbytes - 1;
1541 if ((i = nbytes & 3)) {
1544 *((char *)((caddr_t)ovp + nbytes - RSLOP + i))
1547 nbytes = (nbytes + 3) &~ 3;
1548 *((u_int *)((caddr_t)ovp + nbytes - RSLOP)) = RMAGIC;
1553 DEBUG_m(PerlIO_printf(Perl_debug_log,
1554 "0x%lx: (%05lu) realloc %ld bytes inplace\n",
1555 (unsigned long)res,(unsigned long)(PL_an++),
1557 } else if (incr == 1 && (cp - M_OVERHEAD == last_op)
1558 && (onb > (1 << LOG_OF_MIN_ARENA))) {
1559 MEM_SIZE require, newarena = nbytes, pow;
1562 POW2_OPTIMIZE_ADJUST(newarena);
1563 newarena = newarena + M_OVERHEAD;
1564 /* newarena = (newarena + 3) &~ 3; */
1565 shiftr = (newarena - 1) >> LOG_OF_MIN_ARENA;
1566 pow = LOG_OF_MIN_ARENA + 1;
1567 /* apart from this loop, this is O(1) */
1568 while (shiftr >>= 1)
1570 newarena = (1 << pow) + POW2_OPTIMIZE_SURPLUS(pow * BUCKETS_PER_POW2);
1571 require = newarena - onb - M_OVERHEAD;
1573 if (getpages_adjacent(require)) {
1574 #ifdef DEBUGGING_MSTATS
1576 nmalloc[pow * BUCKETS_PER_POW2]++;
1578 *(cp - M_OVERHEAD) = pow * BUCKETS_PER_POW2; /* Fill index. */
1585 DEBUG_m(PerlIO_printf(Perl_debug_log,
1586 "0x%lx: (%05lu) realloc %ld bytes the hard way\n",
1587 (unsigned long)cp,(unsigned long)(PL_an++),
1589 if ((res = (char*)Perl_malloc(nbytes)) == NULL)
1591 if (cp != res) /* common optimization */
1592 Copy(cp, res, (MEM_SIZE)(nbytes<onb?nbytes:onb), char);
1596 return ((Malloc_t)res);
1600 * Search ``srchlen'' elements of each free list for a block whose
1601 * header starts at ``freep''. If srchlen is -1 search the whole list.
1602 * Return bucket number, or -1 if not found.
1605 findbucket(union overhead *freep, int srchlen)
1607 register union overhead *p;
1610 for (i = 0; i < NBUCKETS; i++) {
1612 for (p = nextf[i]; p && j != srchlen; p = p->ov_next) {
1622 Perl_calloc(register size_t elements, register size_t size)
1624 long sz = elements * size;
1625 Malloc_t p = Perl_malloc(sz);
1628 memset((void*)p, 0, sz);
1634 Perl_malloced_size(void *p)
1636 union overhead *ovp = (union overhead *)
1637 ((caddr_t)p - sizeof (union overhead) * CHUNK_SHIFT);
1638 int bucket = OV_INDEX(ovp);
1640 /* The caller wants to have a complete control over the chunk,
1641 disable the memory checking inside the chunk. */
1642 if (bucket <= MAX_SHORT_BUCKET) {
1643 MEM_SIZE size = BUCKET_SIZE_REAL(bucket);
1644 ovp->ov_size = size + M_OVERHEAD - 1;
1645 *((u_int *)((caddr_t)ovp + size + M_OVERHEAD - RSLOP)) = RMAGIC;
1648 return BUCKET_SIZE_REAL(bucket);
1651 # ifdef BUCKETS_ROOT2
1652 # define MIN_EVEN_REPORT 6
1654 # define MIN_EVEN_REPORT MIN_BUCKET
1657 * mstats - print out statistics about malloc
1659 * Prints two lines of numbers, one showing the length of the free list
1660 * for each size category, the second showing the number of mallocs -
1661 * frees for each size category.
1664 Perl_dump_mstats(pTHX_ char *s)
1666 #ifdef DEBUGGING_MSTATS
1668 register union overhead *p;
1669 int topbucket=0, topbucket_ev=0, topbucket_odd=0, totfree=0, total=0;
1670 u_int nfree[NBUCKETS];
1671 int total_chain = 0;
1672 struct chunk_chain_s* nextchain = chunk_chain;
1674 for (i = MIN_BUCKET ; i < NBUCKETS; i++) {
1675 for (j = 0, p = nextf[i]; p; p = p->ov_next, j++)
1678 totfree += nfree[i] * BUCKET_SIZE_REAL(i);
1679 total += nmalloc[i] * BUCKET_SIZE_REAL(i);
1681 i % 2 ? (topbucket_odd = i) : (topbucket_ev = i);
1686 PerlIO_printf(PerlIO_stderr(),
1687 "Memory allocation statistics %s (buckets %ld(%ld)..%ld(%ld)\n",
1689 (long)BUCKET_SIZE_REAL(MIN_BUCKET),
1690 (long)BUCKET_SIZE(MIN_BUCKET),
1691 (long)BUCKET_SIZE_REAL(topbucket), (long)BUCKET_SIZE(topbucket));
1692 PerlIO_printf(PerlIO_stderr(), "%8d free:", totfree);
1693 for (i = MIN_EVEN_REPORT; i <= topbucket; i += BUCKETS_PER_POW2) {
1694 PerlIO_printf(PerlIO_stderr(),
1695 ((i < 8*BUCKETS_PER_POW2 || i == 10*BUCKETS_PER_POW2)
1697 : ((i < 12*BUCKETS_PER_POW2) ? " %3d" : " %d")),
1700 #ifdef BUCKETS_ROOT2
1701 PerlIO_printf(PerlIO_stderr(), "\n\t ");
1702 for (i = MIN_BUCKET + 1; i <= topbucket_odd; i += BUCKETS_PER_POW2) {
1703 PerlIO_printf(PerlIO_stderr(),
1704 ((i < 8*BUCKETS_PER_POW2 || i == 10*BUCKETS_PER_POW2)
1706 : ((i < 12*BUCKETS_PER_POW2) ? " %3d" : " %d")),
1710 PerlIO_printf(PerlIO_stderr(), "\n%8d used:", total - totfree);
1711 for (i = MIN_EVEN_REPORT; i <= topbucket; i += BUCKETS_PER_POW2) {
1712 PerlIO_printf(PerlIO_stderr(),
1713 ((i < 8*BUCKETS_PER_POW2 || i == 10*BUCKETS_PER_POW2)
1715 : ((i < 12*BUCKETS_PER_POW2) ? " %3d" : " %d")),
1716 nmalloc[i] - nfree[i]);
1718 #ifdef BUCKETS_ROOT2
1719 PerlIO_printf(PerlIO_stderr(), "\n\t ");
1720 for (i = MIN_BUCKET + 1; i <= topbucket_odd; i += BUCKETS_PER_POW2) {
1721 PerlIO_printf(PerlIO_stderr(),
1722 ((i < 8*BUCKETS_PER_POW2 || i == 10*BUCKETS_PER_POW2)
1724 : ((i < 12*BUCKETS_PER_POW2) ? " %3d" : " %d")),
1725 nmalloc[i] - nfree[i]);
1729 total_chain += nextchain->size;
1730 nextchain = nextchain->next;
1732 PerlIO_printf(PerlIO_stderr(), "\nTotal sbrk(): %d/%d:%d. Odd ends: pad+heads+chain+tail: %d+%d+%d+%d.\n",
1733 goodsbrk + sbrk_slack, sbrks, sbrk_good, sbrk_slack,
1734 start_slack, total_chain, sbrked_remains);
1735 #endif /* DEBUGGING_MSTATS */
1739 #ifdef USE_PERL_SBRK
1741 # if defined(__MACHTEN_PPC__) || defined(NeXT) || defined(__NeXT__)
1742 # define PERL_SBRK_VIA_MALLOC
1744 * MachTen's malloc() returns a buffer aligned on a two-byte boundary.
1745 * While this is adequate, it may slow down access to longer data
1746 * types by forcing multiple memory accesses. It also causes
1747 * complaints when RCHECK is in force. So we allocate six bytes
1748 * more than we need to, and return an address rounded up to an
1749 * eight-byte boundary.
1751 * 980701 Dominic Dunlop <domo@computer.org>
1753 # define SYSTEM_ALLOC_ALIGNMENT 2
1756 # ifdef PERL_SBRK_VIA_MALLOC
1758 /* it may seem schizophrenic to use perl's malloc and let it call system */
1759 /* malloc, the reason for that is only the 3.2 version of the OS that had */
1760 /* frequent core dumps within nxzonefreenolock. This sbrk routine put an */
1761 /* end to the cores */
1763 # ifndef SYSTEM_ALLOC
1764 # define SYSTEM_ALLOC(a) malloc(a)
1766 # ifndef SYSTEM_ALLOC_ALIGNMENT
1767 # define SYSTEM_ALLOC_ALIGNMENT MEM_ALIGNBYTES
1770 # endif /* PERL_SBRK_VIA_MALLOC */
1772 static IV Perl_sbrk_oldchunk;
1773 static long Perl_sbrk_oldsize;
1775 # define PERLSBRK_32_K (1<<15)
1776 # define PERLSBRK_64_K (1<<16)
1784 if (!size) return 0;
1786 reqsize = size; /* just for the DEBUG_m statement */
1789 size = (size + 0x7ff) & ~0x7ff;
1791 if (size <= Perl_sbrk_oldsize) {
1792 got = Perl_sbrk_oldchunk;
1793 Perl_sbrk_oldchunk += size;
1794 Perl_sbrk_oldsize -= size;
1796 if (size >= PERLSBRK_32_K) {
1799 size = PERLSBRK_64_K;
1802 # if NEEDED_ALIGNMENT > SYSTEM_ALLOC_ALIGNMENT
1803 size += NEEDED_ALIGNMENT - SYSTEM_ALLOC_ALIGNMENT;
1805 got = (IV)SYSTEM_ALLOC(size);
1806 # if NEEDED_ALIGNMENT > SYSTEM_ALLOC_ALIGNMENT
1807 got = (got + NEEDED_ALIGNMENT - 1) & ~(NEEDED_ALIGNMENT - 1);
1810 /* Chunk is small, register the rest for future allocs. */
1811 Perl_sbrk_oldchunk = got + reqsize;
1812 Perl_sbrk_oldsize = size - reqsize;
1816 DEBUG_m(PerlIO_printf(Perl_debug_log, "sbrk malloc size %ld (reqsize %ld), left size %ld, give addr 0x%lx\n",
1817 size, reqsize, Perl_sbrk_oldsize, got));
1822 #endif /* ! defined USE_PERL_SBRK */