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
291 # define Perl_malloc malloc
294 # define Perl_mfree free
296 # ifndef Perl_realloc
297 # define Perl_realloc realloc
300 # define Perl_calloc calloc
303 # define Perl_strdup strdup
308 # define MUTEX_LOCK(l)
312 # define MUTEX_UNLOCK(l)
316 # define MALLOC_LOCK MUTEX_LOCK_NOCONTEXT(&PL_malloc_mutex)
319 #ifndef MALLOC_UNLOCK
320 # define MALLOC_UNLOCK MUTEX_UNLOCK_NOCONTEXT(&PL_malloc_mutex)
323 # ifndef fatalcroak /* make depend */
324 # define fatalcroak(mess) (write(2, (mess), strlen(mess)), exit(2))
329 # define DEBUG_m(a) \
331 if (PERL_GET_INTERP) { dTHX; if (PL_debug & 128) { a; } } \
338 * The memory is broken into "blocks" which occupy multiples of 2K (and
339 * generally speaking, have size "close" to a power of 2). The addresses
340 * of such *unused* blocks are kept in nextf[i] with big enough i. (nextf
341 * is an array of linked lists.) (Addresses of used blocks are not known.)
343 * Moreover, since the algorithm may try to "bite" smaller blocks out
344 * of unused bigger ones, there are also regions of "irregular" size,
345 * managed separately, by a linked list chunk_chain.
347 * The third type of storage is the sbrk()ed-but-not-yet-used space, its
348 * end and size are kept in last_sbrk_top and sbrked_remains.
350 * Growing blocks "in place":
351 * ~~~~~~~~~~~~~~~~~~~~~~~~~
352 * The address of the block with the greatest address is kept in last_op
353 * (if not known, last_op is 0). If it is known that the memory above
354 * last_op is not continuous, or contains a chunk from chunk_chain,
355 * last_op is set to 0.
357 * The chunk with address last_op may be grown by expanding into
358 * sbrk()ed-but-not-yet-used space, or trying to sbrk() more continuous
361 * Management of last_op:
362 * ~~~~~~~~~~~~~~~~~~~~~
364 * free() never changes the boundaries of blocks, so is not relevant.
366 * The only way realloc() may change the boundaries of blocks is if it
367 * grows a block "in place". However, in the case of success such a
368 * chunk is automatically last_op, and it remains last_op. In the case
369 * of failure getpages_adjacent() clears last_op.
371 * malloc() may change blocks by calling morecore() only.
373 * morecore() may create new blocks by:
374 * a) biting pieces from chunk_chain (cannot create one above last_op);
375 * b) biting a piece from an unused block (if block was last_op, this
376 * may create a chunk from chain above last_op, thus last_op is
377 * invalidated in such a case).
378 * c) biting of sbrk()ed-but-not-yet-used space. This creates
379 * a block which is last_op.
380 * d) Allocating new pages by calling getpages();
382 * getpages() creates a new block. It marks last_op at the bottom of
383 * the chunk of memory it returns.
385 * Active pages footprint:
386 * ~~~~~~~~~~~~~~~~~~~~~~
387 * Note that we do not need to traverse the lists in nextf[i], just take
388 * the first element of this list. However, we *need* to traverse the
389 * list in chunk_chain, but most the time it should be a very short one,
390 * so we do not step on a lot of pages we are not going to use.
394 * get_from_bigger_buckets(): forget to increment price => Quite
398 /* I don't much care whether these are defined in sys/types.h--LAW */
400 #define u_char unsigned char
401 #define u_int unsigned int
403 * I removed the definition of u_bigint which appeared to be u_bigint = UV
404 * u_bigint was only used in TWOK_MASKED and TWOK_SHIFT
405 * where I have used PTR2UV. RMB
407 #define u_short unsigned short
409 /* 286 and atarist like big chunks, which gives too much overhead. */
410 #if (defined(RCHECK) || defined(I286) || defined(atarist) || defined(__MINT__)) && defined(PACK_MALLOC)
415 * The description below is applicable if PACK_MALLOC is not defined.
417 * The overhead on a block is at least 4 bytes. When free, this space
418 * contains a pointer to the next free block, and the bottom two bits must
419 * be zero. When in use, the first byte is set to MAGIC, and the second
420 * byte is the size index. The remaining bytes are for alignment.
421 * If range checking is enabled and the size of the block fits
422 * in two bytes, then the top two bytes hold the size of the requested block
423 * plus the range checking words, and the header word MINUS ONE.
426 union overhead *ov_next; /* when free */
427 #if MEM_ALIGNBYTES > 4
428 double strut; /* alignment problems */
431 u_char ovu_magic; /* magic number */
432 u_char ovu_index; /* bucket # */
434 u_short ovu_size; /* actual block size */
435 u_int ovu_rmagic; /* range magic number */
438 #define ov_magic ovu.ovu_magic
439 #define ov_index ovu.ovu_index
440 #define ov_size ovu.ovu_size
441 #define ov_rmagic ovu.ovu_rmagic
444 #define MAGIC 0xff /* magic # on accounting info */
445 #define RMAGIC 0x55555555 /* magic # on range info */
446 #define RMAGIC_C 0x55 /* magic # on range info */
449 # define RSLOP sizeof (u_int)
450 # ifdef TWO_POT_OPTIMIZE
451 # define MAX_SHORT_BUCKET (12 * BUCKETS_PER_POW2)
453 # define MAX_SHORT_BUCKET (13 * BUCKETS_PER_POW2)
459 #if !defined(PACK_MALLOC) && defined(BUCKETS_ROOT2)
460 # undef BUCKETS_ROOT2
464 # define BUCKET_TABLE_SHIFT 2
465 # define BUCKET_POW2_SHIFT 1
466 # define BUCKETS_PER_POW2 2
468 # define BUCKET_TABLE_SHIFT MIN_BUC_POW2
469 # define BUCKET_POW2_SHIFT 0
470 # define BUCKETS_PER_POW2 1
473 #if !defined(MEM_ALIGNBYTES) || ((MEM_ALIGNBYTES > 4) && !defined(STRICT_ALIGNMENT))
474 /* Figure out the alignment of void*. */
479 # define ALIGN_SMALL ((int)((caddr_t)&(((struct aligner*)0)->p)))
481 # define ALIGN_SMALL MEM_ALIGNBYTES
484 #define IF_ALIGN_8(yes,no) ((ALIGN_SMALL>4) ? (yes) : (no))
487 # define MAX_BUCKET_BY_TABLE 13
488 static u_short buck_size[MAX_BUCKET_BY_TABLE + 1] =
490 0, 0, 0, 0, 4, 4, 8, 12, 16, 24, 32, 48, 64, 80,
492 # define BUCKET_SIZE(i) ((i) % 2 ? buck_size[i] : (1 << ((i) >> BUCKET_POW2_SHIFT)))
493 # define BUCKET_SIZE_REAL(i) ((i) <= MAX_BUCKET_BY_TABLE \
495 : ((1 << ((i) >> BUCKET_POW2_SHIFT)) \
497 + POW2_OPTIMIZE_SURPLUS(i)))
499 # define BUCKET_SIZE(i) (1 << ((i) >> BUCKET_POW2_SHIFT))
500 # define BUCKET_SIZE_REAL(i) (BUCKET_SIZE(i) - MEM_OVERHEAD(i) + POW2_OPTIMIZE_SURPLUS(i))
505 /* In this case there are several possible layout of arenas depending
506 * on the size. Arenas are of sizes multiple to 2K, 2K-aligned, and
507 * have a size close to a power of 2.
509 * Arenas of the size >= 4K keep one chunk only. Arenas of size 2K
510 * may keep one chunk or multiple chunks. Here are the possible
513 * # One chunk only, chunksize 2^k + SOMETHING - ALIGN, k >= 11
515 * INDEX MAGIC1 UNUSED CHUNK1
517 * # Multichunk with sanity checking and chunksize 2^k-ALIGN, k>7
519 * INDEX MAGIC1 MAGIC2 MAGIC3 UNUSED CHUNK1 CHUNK2 CHUNK3 ...
521 * # Multichunk with sanity checking and size 2^k-ALIGN, k=7
523 * INDEX MAGIC1 MAGIC2 MAGIC3 UNUSED CHUNK1 UNUSED CHUNK2 CHUNK3 ...
525 * # Multichunk with sanity checking and size up to 80
527 * INDEX UNUSED MAGIC1 UNUSED MAGIC2 UNUSED ... CHUNK1 CHUNK2 CHUNK3 ...
529 * # No sanity check (usually up to 48=byte-long buckets)
530 * INDEX UNUSED CHUNK1 CHUNK2 ...
532 * Above INDEX and MAGIC are one-byte-long. Sizes of UNUSED are
533 * appropriate to keep algorithms simple and memory aligned. INDEX
534 * encodes the size of the chunk, while MAGICn encodes state (used,
535 * free or non-managed-by-us-so-it-indicates-a-bug) of CHUNKn. MAGIC
536 * is used for sanity checking purposes only. SOMETHING is 0 or 4K
537 * (to make size of big CHUNK accomodate allocations for powers of two
540 * [There is no need to alignment between chunks, since C rules ensure
541 * that structs which need 2^k alignment have sizeof which is
542 * divisible by 2^k. Thus as far as the last chunk is aligned at the
543 * end of the arena, and 2K-alignment does not contradict things,
544 * everything is going to be OK for sizes of chunks 2^n and 2^n +
545 * 2^k. Say, 80-bit buckets will be 16-bit aligned, and as far as we
546 * put allocations for requests in 65..80 range, all is fine.
548 * Note, however, that standard malloc() puts more strict
549 * requirements than the above C rules. Moreover, our algorithms of
550 * realloc() may break this idyll, but we suppose that realloc() does
551 * need not change alignment.]
553 * Is very important to make calculation of the offset of MAGICm as
554 * quick as possible, since it is done on each malloc()/free(). In
555 * fact it is so quick that it has quite little effect on the speed of
556 * doing malloc()/free(). [By default] We forego such calculations
557 * for small chunks, but only to save extra 3% of memory, not because
558 * of speed considerations.
560 * Here is the algorithm [which is the same for all the allocations
561 * schemes above], see OV_MAGIC(block,bucket). Let OFFSETm be the
562 * offset of the CHUNKm from the start of ARENA. Then offset of
563 * MAGICm is (OFFSET1 >> SHIFT) + ADDOFFSET. Here SHIFT and ADDOFFSET
564 * are numbers which depend on the size of the chunks only.
566 * Let as check some sanity conditions. Numbers OFFSETm>>SHIFT are
567 * different for all the chunks in the arena if 2^SHIFT is not greater
568 * than size of the chunks in the arena. MAGIC1 will not overwrite
569 * INDEX provided ADDOFFSET is >0 if OFFSET1 < 2^SHIFT. MAGIClast
570 * will not overwrite CHUNK1 if OFFSET1 > (OFFSETlast >> SHIFT) +
573 * Make SHIFT the maximal possible (there is no point in making it
574 * smaller). Since OFFSETlast is 2K - CHUNKSIZE, above restrictions
575 * give restrictions on OFFSET1 and on ADDOFFSET.
577 * In particular, for chunks of size 2^k with k>=6 we can put
578 * ADDOFFSET to be from 0 to 2^k - 2^(11-k), and have
579 * OFFSET1==chunksize. For chunks of size 80 OFFSET1 of 2K%80=48 is
580 * large enough to have ADDOFFSET between 1 and 16 (similarly for 96,
581 * when ADDOFFSET should be 1). In particular, keeping MAGICs for
582 * these sizes gives no additional size penalty.
584 * However, for chunks of size 2^k with k<=5 this gives OFFSET1 >=
585 * ADDOFSET + 2^(11-k). Keeping ADDOFFSET 0 allows for 2^(11-k)-2^(11-2k)
586 * chunks per arena. This is smaller than 2^(11-k) - 1 which are
587 * needed if no MAGIC is kept. [In fact, having a negative ADDOFFSET
588 * would allow for slightly more buckets per arena for k=2,3.]
590 * Similarly, for chunks of size 3/2*2^k with k<=5 MAGICs would span
591 * the area up to 2^(11-k)+ADDOFFSET. For k=4 this give optimal
592 * ADDOFFSET as -7..0. For k=3 ADDOFFSET can go up to 4 (with tiny
593 * savings for negative ADDOFFSET). For k=5 ADDOFFSET can go -1..16
594 * (with no savings for negative values).
596 * In particular, keeping ADDOFFSET 0 for sizes of chunks up to 2^6
597 * leads to tiny pessimizations in case of sizes 4, 8, 12, 24, and
598 * leads to no contradictions except for size=80 (or 96.)
600 * However, it also makes sense to keep no magic for sizes 48 or less.
601 * This is what we do. In this case one needs ADDOFFSET>=1 also for
602 * chunksizes 12, 24, and 48, unless one gets one less chunk per
605 * The algo of OV_MAGIC(block,bucket) keeps ADDOFFSET 0 until
606 * chunksize of 64, then makes it 1.
608 * This allows for an additional optimization: the above scheme leads
609 * to giant overheads for sizes 128 or more (one whole chunk needs to
610 * be sacrifised to keep INDEX). Instead we use chunks not of size
611 * 2^k, but of size 2^k-ALIGN. If we pack these chunks at the end of
612 * the arena, then the beginnings are still in different 2^k-long
613 * sections of the arena if k>=7 for ALIGN==4, and k>=8 if ALIGN=8.
614 * Thus for k>7 the above algo of calculating the offset of the magic
615 * will still give different answers for different chunks. And to
616 * avoid the overrun of MAGIC1 into INDEX, one needs ADDOFFSET of >=1.
617 * In the case k=7 we just move the first chunk an extra ALIGN
618 * backward inside the ARENA (this is done once per arena lifetime,
619 * thus is not a big overhead). */
620 # define MAX_PACKED_POW2 6
621 # define MAX_PACKED (MAX_PACKED_POW2 * BUCKETS_PER_POW2 + BUCKET_POW2_SHIFT)
622 # define MAX_POW2_ALGO ((1<<(MAX_PACKED_POW2 + 1)) - M_OVERHEAD)
623 # define TWOK_MASK ((1<<LOG_OF_MIN_ARENA) - 1)
624 # define TWOK_MASKED(x) (PTR2UV(x) & ~TWOK_MASK)
625 # define TWOK_SHIFT(x) (PTR2UV(x) & TWOK_MASK)
626 # define OV_INDEXp(block) (INT2PTR(u_char*,TWOK_MASKED(block)))
627 # define OV_INDEX(block) (*OV_INDEXp(block))
628 # define OV_MAGIC(block,bucket) (*(OV_INDEXp(block) + \
629 (TWOK_SHIFT(block)>> \
630 (bucket>>BUCKET_POW2_SHIFT)) + \
631 (bucket >= MIN_NEEDS_SHIFT ? 1 : 0)))
632 /* A bucket can have a shift smaller than it size, we need to
633 shift its magic number so it will not overwrite index: */
634 # ifdef BUCKETS_ROOT2
635 # define MIN_NEEDS_SHIFT (7*BUCKETS_PER_POW2 - 1) /* Shift 80 greater than chunk 64. */
637 # define MIN_NEEDS_SHIFT (7*BUCKETS_PER_POW2) /* Shift 128 greater than chunk 32. */
639 # define CHUNK_SHIFT 0
641 /* Number of active buckets of given ordinal. */
642 #ifdef IGNORE_SMALL_BAD_FREE
643 #define FIRST_BUCKET_WITH_CHECK (6 * BUCKETS_PER_POW2) /* 64 */
644 # define N_BLKS(bucket) ( (bucket) < FIRST_BUCKET_WITH_CHECK \
645 ? ((1<<LOG_OF_MIN_ARENA) - 1)/BUCKET_SIZE(bucket) \
648 # define N_BLKS(bucket) n_blks[bucket]
651 static u_short n_blks[LOG_OF_MIN_ARENA * BUCKETS_PER_POW2] =
653 # if BUCKETS_PER_POW2==1
655 (MIN_BUC_POW2==2 ? 384 : 0),
656 224, 120, 62, 31, 16, 8, 4, 2
659 (MIN_BUC_POW2==2 ? 384 : 0), (MIN_BUC_POW2==2 ? 384 : 0), /* 4, 4 */
660 224, 149, 120, 80, 62, 41, 31, 25, 16, 16, 8, 8, 4, 4, 2, 2
664 /* Shift of the first bucket with the given ordinal inside 2K chunk. */
665 #ifdef IGNORE_SMALL_BAD_FREE
666 # define BLK_SHIFT(bucket) ( (bucket) < FIRST_BUCKET_WITH_CHECK \
667 ? ((1<<LOG_OF_MIN_ARENA) \
668 - BUCKET_SIZE(bucket) * N_BLKS(bucket)) \
671 # define BLK_SHIFT(bucket) blk_shift[bucket]
674 static u_short blk_shift[LOG_OF_MIN_ARENA * BUCKETS_PER_POW2] =
676 # if BUCKETS_PER_POW2==1
678 (MIN_BUC_POW2==2 ? 512 : 0),
679 256, 128, 64, 64, /* 8 to 64 */
680 16*sizeof(union overhead),
681 8*sizeof(union overhead),
682 4*sizeof(union overhead),
683 2*sizeof(union overhead),
686 (MIN_BUC_POW2==2 ? 512 : 0), (MIN_BUC_POW2==2 ? 512 : 0),
687 256, 260, 128, 128, 64, 80, 64, 48, /* 8 to 96 */
688 16*sizeof(union overhead), 16*sizeof(union overhead),
689 8*sizeof(union overhead), 8*sizeof(union overhead),
690 4*sizeof(union overhead), 4*sizeof(union overhead),
691 2*sizeof(union overhead), 2*sizeof(union overhead),
695 # define NEEDED_ALIGNMENT 0x800 /* 2k boundaries */
696 # define WANTED_ALIGNMENT 0x800 /* 2k boundaries */
698 #else /* !PACK_MALLOC */
700 # define OV_MAGIC(block,bucket) (block)->ov_magic
701 # define OV_INDEX(block) (block)->ov_index
702 # define CHUNK_SHIFT 1
703 # define MAX_PACKED -1
704 # define NEEDED_ALIGNMENT MEM_ALIGNBYTES
705 # define WANTED_ALIGNMENT 0x400 /* 1k boundaries */
707 #endif /* !PACK_MALLOC */
709 #define M_OVERHEAD (sizeof(union overhead) + RSLOP)
712 # define MEM_OVERHEAD(bucket) \
713 (bucket <= MAX_PACKED ? 0 : M_OVERHEAD)
714 # ifdef SMALL_BUCKET_VIA_TABLE
715 # define START_SHIFTS_BUCKET ((MAX_PACKED_POW2 + 1) * BUCKETS_PER_POW2)
716 # define START_SHIFT MAX_PACKED_POW2
717 # ifdef BUCKETS_ROOT2 /* Chunks of size 3*2^n. */
718 # define SIZE_TABLE_MAX 80
720 # define SIZE_TABLE_MAX 64
722 static char bucket_of[] =
724 # ifdef BUCKETS_ROOT2 /* Chunks of size 3*2^n. */
725 /* 0 to 15 in 4-byte increments. */
726 (sizeof(void*) > 4 ? 6 : 5), /* 4/8, 5-th bucket for better reports */
728 IF_ALIGN_8(8,7), 8, /* 16/12, 16 */
729 9, 9, 10, 10, /* 24, 32 */
730 11, 11, 11, 11, /* 48 */
731 12, 12, 12, 12, /* 64 */
732 13, 13, 13, 13, /* 80 */
733 13, 13, 13, 13 /* 80 */
734 # else /* !BUCKETS_ROOT2 */
735 /* 0 to 15 in 4-byte increments. */
736 (sizeof(void*) > 4 ? 3 : 2),
742 # endif /* !BUCKETS_ROOT2 */
744 # else /* !SMALL_BUCKET_VIA_TABLE */
745 # define START_SHIFTS_BUCKET MIN_BUCKET
746 # define START_SHIFT (MIN_BUC_POW2 - 1)
747 # endif /* !SMALL_BUCKET_VIA_TABLE */
748 #else /* !PACK_MALLOC */
749 # define MEM_OVERHEAD(bucket) M_OVERHEAD
750 # ifdef SMALL_BUCKET_VIA_TABLE
751 # undef SMALL_BUCKET_VIA_TABLE
753 # define START_SHIFTS_BUCKET MIN_BUCKET
754 # define START_SHIFT (MIN_BUC_POW2 - 1)
755 #endif /* !PACK_MALLOC */
758 * Big allocations are often of the size 2^n bytes. To make them a
759 * little bit better, make blocks of size 2^n+pagesize for big n.
762 #ifdef TWO_POT_OPTIMIZE
764 # ifndef PERL_PAGESIZE
765 # define PERL_PAGESIZE 4096
767 # ifndef FIRST_BIG_POW2
768 # define FIRST_BIG_POW2 15 /* 32K, 16K is used too often. */
770 # define FIRST_BIG_BLOCK (1<<FIRST_BIG_POW2)
771 /* If this value or more, check against bigger blocks. */
772 # define FIRST_BIG_BOUND (FIRST_BIG_BLOCK - M_OVERHEAD)
773 /* If less than this value, goes into 2^n-overhead-block. */
774 # define LAST_SMALL_BOUND ((FIRST_BIG_BLOCK>>1) - M_OVERHEAD)
776 # define POW2_OPTIMIZE_ADJUST(nbytes) \
777 ((nbytes >= FIRST_BIG_BOUND) ? nbytes -= PERL_PAGESIZE : 0)
778 # define POW2_OPTIMIZE_SURPLUS(bucket) \
779 ((bucket >= FIRST_BIG_POW2 * BUCKETS_PER_POW2) ? PERL_PAGESIZE : 0)
781 #else /* !TWO_POT_OPTIMIZE */
782 # define POW2_OPTIMIZE_ADJUST(nbytes)
783 # define POW2_OPTIMIZE_SURPLUS(bucket) 0
784 #endif /* !TWO_POT_OPTIMIZE */
786 #if defined(HAS_64K_LIMIT) && defined(PERL_CORE)
787 # define BARK_64K_LIMIT(what,nbytes,size) \
788 if (nbytes > 0xffff) { \
789 PerlIO_printf(PerlIO_stderr(), \
790 "%s too large: %lx\n", what, size); \
793 #else /* !HAS_64K_LIMIT || !PERL_CORE */
794 # define BARK_64K_LIMIT(what,nbytes,size)
795 #endif /* !HAS_64K_LIMIT || !PERL_CORE */
798 # define MIN_SBRK 2048
802 # define FIRST_SBRK (48*1024)
805 /* Minimal sbrk in percents of what is already alloced. */
806 #ifndef MIN_SBRK_FRAC
807 # define MIN_SBRK_FRAC 3
810 #ifndef SBRK_ALLOW_FAILURES
811 # define SBRK_ALLOW_FAILURES 3
814 #ifndef SBRK_FAILURE_PRICE
815 # define SBRK_FAILURE_PRICE 50
818 #if defined(PERL_EMERGENCY_SBRK) && defined(PERL_CORE)
821 # define BIG_SIZE (1<<16) /* 64K */
824 #ifdef I_MACH_CTHREADS
826 # define MUTEX_LOCK(m) STMT_START { if (*m) mutex_lock(*m); } STMT_END
828 # define MUTEX_UNLOCK(m) STMT_START { if (*m) mutex_unlock(*m); } STMT_END
831 static char *emergency_buffer;
832 static MEM_SIZE emergency_buffer_size;
834 static int findbucket (union overhead *freep, int srchlen);
835 static void morecore (register int bucket);
836 # if defined(DEBUGGING)
837 static void botch (char *diag, char *s);
839 static void add_to_chain (void *p, MEM_SIZE size, MEM_SIZE chip);
840 static Malloc_t emergency_sbrk (MEM_SIZE size);
841 static void* get_from_chain (MEM_SIZE size);
842 static void* get_from_bigger_buckets(int bucket, MEM_SIZE size);
843 static union overhead *getpages (int needed, int *nblksp, int bucket);
844 static int getpages_adjacent(int require);
847 emergency_sbrk(MEM_SIZE size)
849 MEM_SIZE rsize = (((size - 1)>>LOG_OF_MIN_ARENA) + 1)<<LOG_OF_MIN_ARENA;
851 if (size >= BIG_SIZE) {
852 /* Give the possibility to recover: */
854 croak("Out of memory during \"large\" request for %i bytes", size);
857 if (emergency_buffer_size >= rsize) {
858 char *old = emergency_buffer;
860 emergency_buffer_size -= rsize;
861 emergency_buffer += rsize;
865 /* First offense, give a possibility to recover by dieing. */
866 /* No malloc involved here: */
867 GV **gvp = (GV**)hv_fetch(PL_defstash, "^M", 2, 0);
873 if (emergency_buffer_size) {
874 add_to_chain(emergency_buffer, emergency_buffer_size, 0);
875 emergency_buffer_size = 0;
876 emergency_buffer = Nullch;
879 if (!gvp) gvp = (GV**)hv_fetch(PL_defstash, "\015", 1, 0);
880 if (!gvp || !(sv = GvSV(*gvp)) || !SvPOK(sv)
881 || (SvLEN(sv) < (1<<LOG_OF_MIN_ARENA) - M_OVERHEAD)) {
884 return (char *)-1; /* Now die die die... */
886 /* Got it, now detach SvPV: */
888 /* Check alignment: */
889 if ((PTR2UV(pv) - sizeof(union overhead)) & (NEEDED_ALIGNMENT - 1)) {
890 PerlIO_puts(PerlIO_stderr(),"Bad alignment of $^M!\n");
891 return (char *)-1; /* die die die */
894 emergency_buffer = pv - sizeof(union overhead);
895 emergency_buffer_size = malloced_size(pv) + M_OVERHEAD;
898 SvCUR(sv) = SvLEN(sv) = 0;
902 croak("Out of memory during request for %i bytes", size);
907 #else /* !(defined(PERL_EMERGENCY_SBRK) && defined(PERL_CORE)) */
908 # define emergency_sbrk(size) -1
909 #endif /* !(defined(PERL_EMERGENCY_SBRK) && defined(PERL_CORE)) */
912 * nextf[i] is the pointer to the next free block of size 2^i. The
913 * smallest allocatable block is 8 bytes. The overhead information
914 * precedes the data area returned to the user.
916 #define NBUCKETS (32*BUCKETS_PER_POW2 + 1)
917 static union overhead *nextf[NBUCKETS];
920 #define sbrk(a) Perl_sbrk(a)
921 Malloc_t Perl_sbrk (int size);
923 #ifdef DONT_DECLARE_STD
928 extern Malloc_t sbrk(int);
932 #ifdef DEBUGGING_MSTATS
934 * nmalloc[i] is the difference between the number of mallocs and frees
935 * for a given block size.
937 static u_int nmalloc[NBUCKETS];
938 static u_int sbrk_slack;
939 static u_int start_slack;
942 static u_int goodsbrk;
946 #define ASSERT(p,diag) if (!(p)) botch(diag,STRINGIFY(p)); else
948 botch(char *diag, char *s)
951 PerlIO_printf(PerlIO_stderr(), "assertion botched (%s?): %s\n", diag, s);
955 #define ASSERT(p, diag)
959 Perl_malloc(register size_t nbytes)
961 register union overhead *p;
963 register MEM_SIZE shiftr;
965 #if defined(DEBUGGING) || defined(RCHECK)
966 MEM_SIZE size = nbytes;
969 BARK_64K_LIMIT("Allocation",nbytes,nbytes);
971 if ((long)nbytes < 0)
972 croak("%s", "panic: malloc");
976 * Convert amount of memory requested into
977 * closest block size stored in hash buckets
978 * which satisfies request. Account for
979 * space used per block for accounting.
982 # ifdef SMALL_BUCKET_VIA_TABLE
985 else if (nbytes <= SIZE_TABLE_MAX) {
986 bucket = bucket_of[(nbytes - 1) >> BUCKET_TABLE_SHIFT];
991 if (nbytes <= MAX_POW2_ALGO) goto do_shifts;
996 POW2_OPTIMIZE_ADJUST(nbytes);
997 nbytes += M_OVERHEAD;
998 nbytes = (nbytes + 3) &~ 3;
1000 shiftr = (nbytes - 1) >> START_SHIFT;
1001 bucket = START_SHIFTS_BUCKET;
1002 /* apart from this loop, this is O(1) */
1003 while (shiftr >>= 1)
1004 bucket += BUCKETS_PER_POW2;
1008 * If nothing in hash bucket right now,
1009 * request more memory from the system.
1011 if (nextf[bucket] == NULL)
1013 if ((p = nextf[bucket]) == NULL) {
1019 PerlIO_puts(PerlIO_stderr(),"Out of memory!\n");
1027 DEBUG_m(PerlIO_printf(Perl_debug_log,
1028 "0x%"UVxf": (%05lu) malloc %ld bytes\n",
1029 PTR2UV(p+1), (unsigned long)(PL_an++),
1032 /* remove from linked list */
1034 if ((PTR2UV(p)) & (MEM_ALIGNBYTES - 1)) {
1036 PerlIO_printf(PerlIO_stderr(),
1037 "Unaligned pointer in the free chain 0x%"UVxf"\n",
1040 if ((PTR2UV(p->ov_next)) & (MEM_ALIGNBYTES - 1)) {
1042 PerlIO_printf(PerlIO_stderr(),
1043 "Unaligned `next' pointer in the free "
1044 "chain 0x"UVxf" at 0x%"UVxf"\n",
1045 PTR2UV(p->ov_next), PTR2UV(p));
1048 nextf[bucket] = p->ov_next;
1052 #ifdef IGNORE_SMALL_BAD_FREE
1053 if (bucket >= FIRST_BUCKET_WITH_CHECK)
1055 OV_MAGIC(p, bucket) = MAGIC;
1057 OV_INDEX(p) = bucket;
1061 * Record allocated size of block and
1062 * bound space with magic numbers.
1064 p->ov_rmagic = RMAGIC;
1065 if (bucket <= MAX_SHORT_BUCKET) {
1068 nbytes = size + M_OVERHEAD;
1069 p->ov_size = nbytes - 1;
1070 if ((i = nbytes & 3)) {
1073 *((char *)((caddr_t)p + nbytes - RSLOP + i)) = RMAGIC_C;
1075 nbytes = (nbytes + 3) &~ 3;
1076 *((u_int *)((caddr_t)p + nbytes - RSLOP)) = RMAGIC;
1079 return ((Malloc_t)(p + CHUNK_SHIFT));
1082 static char *last_sbrk_top;
1083 static char *last_op; /* This arena can be easily extended. */
1084 static int sbrked_remains;
1085 static int sbrk_good = SBRK_ALLOW_FAILURES * SBRK_FAILURE_PRICE;
1087 #ifdef DEBUGGING_MSTATS
1091 struct chunk_chain_s {
1092 struct chunk_chain_s *next;
1095 static struct chunk_chain_s *chunk_chain;
1096 static int n_chunks;
1097 static char max_bucket;
1099 /* Cutoff a piece of one of the chunks in the chain. Prefer smaller chunk. */
1101 get_from_chain(MEM_SIZE size)
1103 struct chunk_chain_s *elt = chunk_chain, **oldp = &chunk_chain;
1104 struct chunk_chain_s **oldgoodp = NULL;
1105 long min_remain = LONG_MAX;
1108 if (elt->size >= size) {
1109 long remains = elt->size - size;
1110 if (remains >= 0 && remains < min_remain) {
1112 min_remain = remains;
1118 oldp = &( elt->next );
1121 if (!oldgoodp) return NULL;
1123 void *ret = *oldgoodp;
1124 struct chunk_chain_s *next = (*oldgoodp)->next;
1126 *oldgoodp = (struct chunk_chain_s *)((char*)ret + size);
1127 (*oldgoodp)->size = min_remain;
1128 (*oldgoodp)->next = next;
1131 void *ret = *oldgoodp;
1132 *oldgoodp = (*oldgoodp)->next;
1139 add_to_chain(void *p, MEM_SIZE size, MEM_SIZE chip)
1141 struct chunk_chain_s *next = chunk_chain;
1142 char *cp = (char*)p;
1145 chunk_chain = (struct chunk_chain_s *)cp;
1146 chunk_chain->size = size - chip;
1147 chunk_chain->next = next;
1152 get_from_bigger_buckets(int bucket, MEM_SIZE size)
1155 static int bucketprice[NBUCKETS];
1156 while (bucket <= max_bucket) {
1157 /* We postpone stealing from bigger buckets until we want it
1159 if (nextf[bucket] && bucketprice[bucket]++ >= price) {
1161 void *ret = (void*)(nextf[bucket] - 1 + CHUNK_SHIFT);
1162 bucketprice[bucket] = 0;
1163 if (((char*)nextf[bucket]) - M_OVERHEAD == last_op) {
1164 last_op = NULL; /* Disable optimization */
1166 nextf[bucket] = nextf[bucket]->ov_next;
1167 #ifdef DEBUGGING_MSTATS
1169 start_slack -= M_OVERHEAD;
1171 add_to_chain(ret, (BUCKET_SIZE(bucket) +
1172 POW2_OPTIMIZE_SURPLUS(bucket)),
1181 static union overhead *
1182 getpages(int needed, int *nblksp, int bucket)
1184 /* Need to do (possibly expensive) system call. Try to
1185 optimize it for rare calling. */
1186 MEM_SIZE require = needed - sbrked_remains;
1188 union overhead *ovp;
1191 if (sbrk_good > 0) {
1192 if (!last_sbrk_top && require < FIRST_SBRK)
1193 require = FIRST_SBRK;
1194 else if (require < MIN_SBRK) require = MIN_SBRK;
1196 if (require < goodsbrk * MIN_SBRK_FRAC / 100)
1197 require = goodsbrk * MIN_SBRK_FRAC / 100;
1198 require = ((require - 1 + MIN_SBRK) / MIN_SBRK) * MIN_SBRK;
1205 DEBUG_m(PerlIO_printf(Perl_debug_log,
1206 "sbrk(%ld) for %ld-byte-long arena\n",
1207 (long)require, (long) needed));
1208 cp = (char *)sbrk(require);
1209 #ifdef DEBUGGING_MSTATS
1212 if (cp == last_sbrk_top) {
1213 /* Common case, anything is fine. */
1215 ovp = (union overhead *) (cp - sbrked_remains);
1216 last_op = cp - sbrked_remains;
1217 sbrked_remains = require - (needed - sbrked_remains);
1218 } else if (cp == (char *)-1) { /* no more room! */
1219 ovp = (union overhead *)emergency_sbrk(needed);
1220 if (ovp == (union overhead *)-1)
1222 if (((char*)ovp) > last_op) { /* Cannot happen with current emergency_sbrk() */
1226 } else { /* Non-continuous or first sbrk(). */
1227 long add = sbrked_remains;
1230 if (sbrked_remains) { /* Put rest into chain, we
1231 cannot use it right now. */
1232 add_to_chain((void*)(last_sbrk_top - sbrked_remains),
1236 /* Second, check alignment. */
1239 #if !defined(atarist) && !defined(__MINT__) /* on the atari we dont have to worry about this */
1240 # ifndef I286 /* The sbrk(0) call on the I286 always returns the next segment */
1241 /* WANTED_ALIGNMENT may be more than NEEDED_ALIGNMENT, but this may
1242 improve performance of memory access. */
1243 if (PTR2UV(cp) & (WANTED_ALIGNMENT - 1)) { /* Not aligned. */
1244 slack = WANTED_ALIGNMENT - (PTR2UV(cp) & (WANTED_ALIGNMENT - 1));
1248 #endif /* !atarist && !MINT */
1251 DEBUG_m(PerlIO_printf(Perl_debug_log,
1252 "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",
1253 (long)add, (long) slack,
1254 (long) sbrked_remains));
1255 newcp = (char *)sbrk(add);
1256 #if defined(DEBUGGING_MSTATS)
1260 if (newcp != cp + require) {
1261 /* Too bad: even rounding sbrk() is not continuous.*/
1262 DEBUG_m(PerlIO_printf(Perl_debug_log,
1263 "failed to fix bad sbrk()\n"));
1267 fatalcroak("panic: Off-page sbrk\n");
1270 if (sbrked_remains) {
1272 #if defined(DEBUGGING_MSTATS)
1273 sbrk_slack += require;
1276 DEBUG_m(PerlIO_printf(Perl_debug_log,
1277 "straight sbrk(%ld)\n",
1279 cp = (char *)sbrk(require);
1280 #ifdef DEBUGGING_MSTATS
1283 if (cp == (char *)-1)
1286 sbrk_good = -1; /* Disable optimization!
1287 Continue with not-aligned... */
1290 require += sbrked_remains;
1294 if (last_sbrk_top) {
1295 sbrk_good -= SBRK_FAILURE_PRICE;
1298 ovp = (union overhead *) cp;
1300 * Round up to minimum allocation size boundary
1301 * and deduct from block count to reflect.
1304 # if NEEDED_ALIGNMENT > MEM_ALIGNBYTES
1305 if (PTR2UV(ovp) & (NEEDED_ALIGNMENT - 1))
1306 fatalcroak("Misalignment of sbrk()\n");
1309 #ifndef I286 /* Again, this should always be ok on an 80286 */
1310 if (PTR2UV(ovp) & (MEM_ALIGNBYTES - 1)) {
1311 DEBUG_m(PerlIO_printf(Perl_debug_log,
1312 "fixing sbrk(): %d bytes off machine alignement\n",
1313 (int)(PTR2UV(ovp) & (MEM_ALIGNBYTES - 1))));
1314 ovp = INT2PTR(union overhead *,(PTR2UV(ovp) + MEM_ALIGNBYTES) &
1315 (MEM_ALIGNBYTES - 1));
1317 # if defined(DEBUGGING_MSTATS)
1318 /* This is only approx. if TWO_POT_OPTIMIZE: */
1319 sbrk_slack += (1 << (bucket >> BUCKET_POW2_SHIFT));
1323 ; /* Finish `else' */
1324 sbrked_remains = require - needed;
1327 last_sbrk_top = cp + require;
1328 #ifdef DEBUGGING_MSTATS
1329 goodsbrk += require;
1335 getpages_adjacent(int require)
1337 if (require <= sbrked_remains) {
1338 sbrked_remains -= require;
1342 require -= sbrked_remains;
1343 /* We do not try to optimize sbrks here, we go for place. */
1344 cp = (char*) sbrk(require);
1345 #ifdef DEBUGGING_MSTATS
1347 goodsbrk += require;
1349 if (cp == last_sbrk_top) {
1351 last_sbrk_top = cp + require;
1353 if (cp == (char*)-1) { /* Out of memory */
1354 #ifdef DEBUGGING_MSTATS
1355 goodsbrk -= require;
1359 /* Report the failure: */
1361 add_to_chain((void*)(last_sbrk_top - sbrked_remains),
1363 add_to_chain((void*)cp, require, 0);
1364 sbrk_good -= SBRK_FAILURE_PRICE;
1376 * Allocate more memory to the indicated bucket.
1379 morecore(register int bucket)
1381 register union overhead *ovp;
1382 register int rnu; /* 2^rnu bytes will be requested */
1383 int nblks; /* become nblks blocks of the desired size */
1384 register MEM_SIZE siz, needed;
1388 if (bucket == sizeof(MEM_SIZE)*8*BUCKETS_PER_POW2) {
1390 croak("%s", "Out of memory during ridiculously large request");
1392 if (bucket > max_bucket)
1393 max_bucket = bucket;
1395 rnu = ( (bucket <= (LOG_OF_MIN_ARENA << BUCKET_POW2_SHIFT))
1397 : (bucket >> BUCKET_POW2_SHIFT) );
1398 /* This may be overwritten later: */
1399 nblks = 1 << (rnu - (bucket >> BUCKET_POW2_SHIFT)); /* how many blocks to get */
1400 needed = ((MEM_SIZE)1 << rnu) + POW2_OPTIMIZE_SURPLUS(bucket);
1401 if (nextf[rnu << BUCKET_POW2_SHIFT]) { /* 2048b bucket. */
1402 ovp = nextf[rnu << BUCKET_POW2_SHIFT] - 1 + CHUNK_SHIFT;
1403 nextf[rnu << BUCKET_POW2_SHIFT]
1404 = nextf[rnu << BUCKET_POW2_SHIFT]->ov_next;
1405 #ifdef DEBUGGING_MSTATS
1406 nmalloc[rnu << BUCKET_POW2_SHIFT]--;
1407 start_slack -= M_OVERHEAD;
1409 DEBUG_m(PerlIO_printf(Perl_debug_log,
1410 "stealing %ld bytes from %ld arena\n",
1411 (long) needed, (long) rnu << BUCKET_POW2_SHIFT));
1412 } else if (chunk_chain
1413 && (ovp = (union overhead*) get_from_chain(needed))) {
1414 DEBUG_m(PerlIO_printf(Perl_debug_log,
1415 "stealing %ld bytes from chain\n",
1417 } else if ( (ovp = (union overhead*)
1418 get_from_bigger_buckets((rnu << BUCKET_POW2_SHIFT) + 1,
1420 DEBUG_m(PerlIO_printf(Perl_debug_log,
1421 "stealing %ld bytes from bigger buckets\n",
1423 } else if (needed <= sbrked_remains) {
1424 ovp = (union overhead *)(last_sbrk_top - sbrked_remains);
1425 sbrked_remains -= needed;
1426 last_op = (char*)ovp;
1428 ovp = getpages(needed, &nblks, bucket);
1434 * Add new memory allocated to that on
1435 * free list for this hash bucket.
1437 siz = BUCKET_SIZE(bucket);
1439 *(u_char*)ovp = bucket; /* Fill index. */
1440 if (bucket <= MAX_PACKED) {
1441 ovp = (union overhead *) ((char*)ovp + BLK_SHIFT(bucket));
1442 nblks = N_BLKS(bucket);
1443 # ifdef DEBUGGING_MSTATS
1444 start_slack += BLK_SHIFT(bucket);
1446 } else if (bucket < LOG_OF_MIN_ARENA * BUCKETS_PER_POW2) {
1447 ovp = (union overhead *) ((char*)ovp + BLK_SHIFT(bucket));
1448 siz -= sizeof(union overhead);
1449 } else ovp++; /* One chunk per block. */
1450 #endif /* PACK_MALLOC */
1451 nextf[bucket] = ovp;
1452 #ifdef DEBUGGING_MSTATS
1453 nmalloc[bucket] += nblks;
1454 if (bucket > MAX_PACKED) {
1455 start_slack += M_OVERHEAD * nblks;
1458 while (--nblks > 0) {
1459 ovp->ov_next = (union overhead *)((caddr_t)ovp + siz);
1460 ovp = (union overhead *)((caddr_t)ovp + siz);
1462 /* Not all sbrks return zeroed memory.*/
1463 ovp->ov_next = (union overhead *)NULL;
1465 if (bucket == 7*BUCKETS_PER_POW2) { /* Special case, explanation is above. */
1466 union overhead *n_op = nextf[7*BUCKETS_PER_POW2]->ov_next;
1467 nextf[7*BUCKETS_PER_POW2] =
1468 (union overhead *)((caddr_t)nextf[7*BUCKETS_PER_POW2]
1469 - sizeof(union overhead));
1470 nextf[7*BUCKETS_PER_POW2]->ov_next = n_op;
1472 #endif /* !PACK_MALLOC */
1476 Perl_mfree(void *mp)
1478 register MEM_SIZE size;
1479 register union overhead *ovp;
1480 char *cp = (char*)mp;
1485 DEBUG_m(PerlIO_printf(Perl_debug_log,
1486 "0x%"UVxf": (%05lu) free\n",
1487 PTR2UV(cp), (unsigned long)(PL_an++)));
1491 ovp = (union overhead *)((caddr_t)cp
1492 - sizeof (union overhead) * CHUNK_SHIFT);
1494 bucket = OV_INDEX(ovp);
1496 #ifdef IGNORE_SMALL_BAD_FREE
1497 if ((bucket >= FIRST_BUCKET_WITH_CHECK)
1498 && (OV_MAGIC(ovp, bucket) != MAGIC))
1500 if (OV_MAGIC(ovp, bucket) != MAGIC)
1503 static int bad_free_warn = -1;
1504 if (bad_free_warn == -1) {
1506 char *pbf = PerlEnv_getenv("PERL_BADFREE");
1507 bad_free_warn = (pbf) ? atoi(pbf) : 1;
1512 warn("%s free() ignored",
1513 ovp->ov_rmagic == RMAGIC - 1 ? "Duplicate" : "Bad");
1515 warn("%s", "Bad free() ignored");
1517 return; /* sanity */
1520 ASSERT(ovp->ov_rmagic == RMAGIC, "chunk's head overwrite");
1521 if (OV_INDEX(ovp) <= MAX_SHORT_BUCKET) {
1523 MEM_SIZE nbytes = ovp->ov_size + 1;
1525 if ((i = nbytes & 3)) {
1528 ASSERT(*((char *)((caddr_t)ovp + nbytes - RSLOP + i))
1529 == RMAGIC_C, "chunk's tail overwrite");
1532 nbytes = (nbytes + 3) &~ 3;
1533 ASSERT(*(u_int *)((caddr_t)ovp + nbytes - RSLOP) == RMAGIC, "chunk's tail overwrite");
1535 ovp->ov_rmagic = RMAGIC - 1;
1537 ASSERT(OV_INDEX(ovp) < NBUCKETS, "chunk's head overwrite");
1538 size = OV_INDEX(ovp);
1541 ovp->ov_next = nextf[size];
1546 /* There is no need to do any locking in realloc (with an exception of
1547 trying to grow in place if we are at the end of the chain).
1548 If somebody calls us from a different thread with the same address,
1549 we are sole anyway. */
1552 Perl_realloc(void *mp, size_t nbytes)
1554 register MEM_SIZE onb;
1555 union overhead *ovp;
1558 register int bucket;
1559 int incr; /* 1 if does not fit, -1 if "easily" fits in a
1560 smaller bucket, otherwise 0. */
1561 char *cp = (char*)mp;
1563 #if defined(DEBUGGING) || !defined(PERL_CORE)
1564 MEM_SIZE size = nbytes;
1566 if ((long)nbytes < 0)
1567 croak("%s", "panic: realloc");
1570 BARK_64K_LIMIT("Reallocation",nbytes,size);
1572 return Perl_malloc(nbytes);
1574 ovp = (union overhead *)((caddr_t)cp
1575 - sizeof (union overhead) * CHUNK_SHIFT);
1576 bucket = OV_INDEX(ovp);
1578 #ifdef IGNORE_SMALL_BAD_FREE
1579 if ((bucket >= FIRST_BUCKET_WITH_CHECK)
1580 && (OV_MAGIC(ovp, bucket) != MAGIC))
1582 if (OV_MAGIC(ovp, bucket) != MAGIC)
1585 static int bad_free_warn = -1;
1586 if (bad_free_warn == -1) {
1588 char *pbf = PerlEnv_getenv("PERL_BADFREE");
1589 bad_free_warn = (pbf) ? atoi(pbf) : 1;
1594 warn("%srealloc() %signored",
1595 (ovp->ov_rmagic == RMAGIC - 1 ? "" : "Bad "),
1596 ovp->ov_rmagic == RMAGIC - 1 ? "of freed memory " : "");
1598 warn("%s", "Bad realloc() ignored");
1600 return Nullch; /* sanity */
1603 onb = BUCKET_SIZE_REAL(bucket);
1605 * avoid the copy if same size block.
1606 * We are not agressive with boundary cases. Note that it might
1607 * (for a small number of cases) give false negative if
1608 * both new size and old one are in the bucket for
1609 * FIRST_BIG_POW2, but the new one is near the lower end.
1611 * We do not try to go to 1.5 times smaller bucket so far.
1613 if (nbytes > onb) incr = 1;
1615 #ifdef DO_NOT_TRY_HARDER_WHEN_SHRINKING
1616 if ( /* This is a little bit pessimal if PACK_MALLOC: */
1617 nbytes > ( (onb >> 1) - M_OVERHEAD )
1618 # ifdef TWO_POT_OPTIMIZE
1619 || (bucket == FIRST_BIG_POW2 && nbytes >= LAST_SMALL_BOUND )
1622 #else /* !DO_NOT_TRY_HARDER_WHEN_SHRINKING */
1623 prev_bucket = ( (bucket > MAX_PACKED + 1)
1624 ? bucket - BUCKETS_PER_POW2
1626 if (nbytes > BUCKET_SIZE_REAL(prev_bucket))
1627 #endif /* !DO_NOT_TRY_HARDER_WHEN_SHRINKING */
1631 #ifdef STRESS_REALLOC
1638 * Record new allocated size of block and
1639 * bound space with magic numbers.
1641 if (OV_INDEX(ovp) <= MAX_SHORT_BUCKET) {
1642 int i, nb = ovp->ov_size + 1;
1647 ASSERT(*((char *)((caddr_t)ovp + nb - RSLOP + i)) == RMAGIC_C, "chunk's tail overwrite");
1651 ASSERT(*(u_int *)((caddr_t)ovp + nb - RSLOP) == RMAGIC, "chunk's tail overwrite");
1653 * Convert amount of memory requested into
1654 * closest block size stored in hash buckets
1655 * which satisfies request. Account for
1656 * space used per block for accounting.
1658 nbytes += M_OVERHEAD;
1659 ovp->ov_size = nbytes - 1;
1660 if ((i = nbytes & 3)) {
1663 *((char *)((caddr_t)ovp + nbytes - RSLOP + i))
1666 nbytes = (nbytes + 3) &~ 3;
1667 *((u_int *)((caddr_t)ovp + nbytes - RSLOP)) = RMAGIC;
1671 DEBUG_m(PerlIO_printf(Perl_debug_log,
1672 "0x%"UVxf": (%05lu) realloc %ld bytes inplace\n",
1673 PTR2UV(res),(unsigned long)(PL_an++),
1675 } else if (incr == 1 && (cp - M_OVERHEAD == last_op)
1676 && (onb > (1 << LOG_OF_MIN_ARENA))) {
1677 MEM_SIZE require, newarena = nbytes, pow;
1680 POW2_OPTIMIZE_ADJUST(newarena);
1681 newarena = newarena + M_OVERHEAD;
1682 /* newarena = (newarena + 3) &~ 3; */
1683 shiftr = (newarena - 1) >> LOG_OF_MIN_ARENA;
1684 pow = LOG_OF_MIN_ARENA + 1;
1685 /* apart from this loop, this is O(1) */
1686 while (shiftr >>= 1)
1688 newarena = (1 << pow) + POW2_OPTIMIZE_SURPLUS(pow * BUCKETS_PER_POW2);
1689 require = newarena - onb - M_OVERHEAD;
1692 if (cp - M_OVERHEAD == last_op /* We *still* are the last chunk */
1693 && getpages_adjacent(require)) {
1694 #ifdef DEBUGGING_MSTATS
1696 nmalloc[pow * BUCKETS_PER_POW2]++;
1698 *(cp - M_OVERHEAD) = pow * BUCKETS_PER_POW2; /* Fill index. */
1707 DEBUG_m(PerlIO_printf(Perl_debug_log,
1708 "0x%"UVxf": (%05lu) realloc %ld bytes the hard way\n",
1709 PTR2UV(cp),(unsigned long)(PL_an++),
1711 if ((res = (char*)Perl_malloc(nbytes)) == NULL)
1713 if (cp != res) /* common optimization */
1714 Copy(cp, res, (MEM_SIZE)(nbytes<onb?nbytes:onb), char);
1717 return ((Malloc_t)res);
1721 * Search ``srchlen'' elements of each free list for a block whose
1722 * header starts at ``freep''. If srchlen is -1 search the whole list.
1723 * Return bucket number, or -1 if not found.
1726 findbucket(union overhead *freep, int srchlen)
1728 register union overhead *p;
1731 for (i = 0; i < NBUCKETS; i++) {
1733 for (p = nextf[i]; p && j != srchlen; p = p->ov_next) {
1743 Perl_calloc(register size_t elements, register size_t size)
1745 long sz = elements * size;
1746 Malloc_t p = Perl_malloc(sz);
1749 memset((void*)p, 0, sz);
1755 Perl_strdup(const char *s)
1757 MEM_SIZE l = strlen(s);
1758 char *s1 = (char *)Perl_malloc(l+1);
1760 Copy(s, s1, (MEM_SIZE)(l+1), char);
1766 Perl_putenv(char *a)
1768 /* Sometimes system's putenv conflicts with my_setenv() - this is system
1769 malloc vs Perl's free(). */
1776 while (*val && *val != '=')
1781 if (l < sizeof(buf))
1784 var = Perl_malloc(l + 1);
1785 Copy(a, var, l, char);
1787 my_setenv(var, val+1);
1795 Perl_malloced_size(void *p)
1797 union overhead *ovp = (union overhead *)
1798 ((caddr_t)p - sizeof (union overhead) * CHUNK_SHIFT);
1799 int bucket = OV_INDEX(ovp);
1801 /* The caller wants to have a complete control over the chunk,
1802 disable the memory checking inside the chunk. */
1803 if (bucket <= MAX_SHORT_BUCKET) {
1804 MEM_SIZE size = BUCKET_SIZE_REAL(bucket);
1805 ovp->ov_size = size + M_OVERHEAD - 1;
1806 *((u_int *)((caddr_t)ovp + size + M_OVERHEAD - RSLOP)) = RMAGIC;
1809 return BUCKET_SIZE_REAL(bucket);
1812 # ifdef BUCKETS_ROOT2
1813 # define MIN_EVEN_REPORT 6
1815 # define MIN_EVEN_REPORT MIN_BUCKET
1818 * mstats - print out statistics about malloc
1820 * Prints two lines of numbers, one showing the length of the free list
1821 * for each size category, the second showing the number of mallocs -
1822 * frees for each size category.
1825 Perl_dump_mstats(pTHX_ char *s)
1827 #ifdef DEBUGGING_MSTATS
1829 register union overhead *p;
1830 int topbucket=0, topbucket_ev=0, topbucket_odd=0, totfree=0, total=0;
1831 u_int nfree[NBUCKETS];
1832 int total_chain = 0;
1833 struct chunk_chain_s* nextchain;
1836 for (i = MIN_BUCKET ; i < NBUCKETS; i++) {
1837 for (j = 0, p = nextf[i]; p; p = p->ov_next, j++)
1840 totfree += nfree[i] * BUCKET_SIZE_REAL(i);
1841 total += nmalloc[i] * BUCKET_SIZE_REAL(i);
1843 i % 2 ? (topbucket_odd = i) : (topbucket_ev = i);
1847 nextchain = chunk_chain;
1849 total_chain += nextchain->size;
1850 nextchain = nextchain->next;
1854 PerlIO_printf(Perl_error_log,
1855 "Memory allocation statistics %s (buckets %ld(%ld)..%ld(%ld)\n",
1857 (long)BUCKET_SIZE_REAL(MIN_BUCKET),
1858 (long)BUCKET_SIZE(MIN_BUCKET),
1859 (long)BUCKET_SIZE_REAL(topbucket), (long)BUCKET_SIZE(topbucket));
1860 PerlIO_printf(Perl_error_log, "%8d free:", totfree);
1861 for (i = MIN_EVEN_REPORT; i <= topbucket; i += BUCKETS_PER_POW2) {
1862 PerlIO_printf(Perl_error_log,
1863 ((i < 8*BUCKETS_PER_POW2 || i == 10*BUCKETS_PER_POW2)
1865 : ((i < 12*BUCKETS_PER_POW2) ? " %3d" : " %d")),
1868 #ifdef BUCKETS_ROOT2
1869 PerlIO_printf(Perl_error_log, "\n\t ");
1870 for (i = MIN_BUCKET + 1; i <= topbucket_odd; i += BUCKETS_PER_POW2) {
1871 PerlIO_printf(Perl_error_log,
1872 ((i < 8*BUCKETS_PER_POW2 || i == 10*BUCKETS_PER_POW2)
1874 : ((i < 12*BUCKETS_PER_POW2) ? " %3d" : " %d")),
1878 PerlIO_printf(Perl_error_log, "\n%8d used:", total - totfree);
1879 for (i = MIN_EVEN_REPORT; i <= topbucket; i += BUCKETS_PER_POW2) {
1880 PerlIO_printf(Perl_error_log,
1881 ((i < 8*BUCKETS_PER_POW2 || i == 10*BUCKETS_PER_POW2)
1883 : ((i < 12*BUCKETS_PER_POW2) ? " %3d" : " %d")),
1884 nmalloc[i] - nfree[i]);
1886 #ifdef BUCKETS_ROOT2
1887 PerlIO_printf(Perl_error_log, "\n\t ");
1888 for (i = MIN_BUCKET + 1; i <= topbucket_odd; i += BUCKETS_PER_POW2) {
1889 PerlIO_printf(Perl_error_log,
1890 ((i < 8*BUCKETS_PER_POW2 || i == 10*BUCKETS_PER_POW2)
1892 : ((i < 12*BUCKETS_PER_POW2) ? " %3d" : " %d")),
1893 nmalloc[i] - nfree[i]);
1896 PerlIO_printf(Perl_error_log, "\nTotal sbrk(): %d/%d:%d. Odd ends: pad+heads+chain+tail: %d+%d+%d+%d.\n",
1897 goodsbrk + sbrk_slack, sbrks, sbrk_good, sbrk_slack,
1898 start_slack, total_chain, sbrked_remains);
1899 #endif /* DEBUGGING_MSTATS */
1903 #ifdef USE_PERL_SBRK
1905 # if defined(__MACHTEN_PPC__) || defined(NeXT) || defined(__NeXT__)
1906 # define PERL_SBRK_VIA_MALLOC
1908 * MachTen's malloc() returns a buffer aligned on a two-byte boundary.
1909 * While this is adequate, it may slow down access to longer data
1910 * types by forcing multiple memory accesses. It also causes
1911 * complaints when RCHECK is in force. So we allocate six bytes
1912 * more than we need to, and return an address rounded up to an
1913 * eight-byte boundary.
1915 * 980701 Dominic Dunlop <domo@computer.org>
1917 # define SYSTEM_ALLOC_ALIGNMENT 2
1920 # ifdef PERL_SBRK_VIA_MALLOC
1922 /* it may seem schizophrenic to use perl's malloc and let it call system */
1923 /* malloc, the reason for that is only the 3.2 version of the OS that had */
1924 /* frequent core dumps within nxzonefreenolock. This sbrk routine put an */
1925 /* end to the cores */
1927 # ifndef SYSTEM_ALLOC
1928 # define SYSTEM_ALLOC(a) malloc(a)
1930 # ifndef SYSTEM_ALLOC_ALIGNMENT
1931 # define SYSTEM_ALLOC_ALIGNMENT MEM_ALIGNBYTES
1934 # endif /* PERL_SBRK_VIA_MALLOC */
1936 static IV Perl_sbrk_oldchunk;
1937 static long Perl_sbrk_oldsize;
1939 # define PERLSBRK_32_K (1<<15)
1940 # define PERLSBRK_64_K (1<<16)
1948 if (!size) return 0;
1950 reqsize = size; /* just for the DEBUG_m statement */
1953 size = (size + 0x7ff) & ~0x7ff;
1955 if (size <= Perl_sbrk_oldsize) {
1956 got = Perl_sbrk_oldchunk;
1957 Perl_sbrk_oldchunk += size;
1958 Perl_sbrk_oldsize -= size;
1960 if (size >= PERLSBRK_32_K) {
1963 size = PERLSBRK_64_K;
1966 # if NEEDED_ALIGNMENT > SYSTEM_ALLOC_ALIGNMENT
1967 size += NEEDED_ALIGNMENT - SYSTEM_ALLOC_ALIGNMENT;
1969 got = (IV)SYSTEM_ALLOC(size);
1970 # if NEEDED_ALIGNMENT > SYSTEM_ALLOC_ALIGNMENT
1971 got = (got + NEEDED_ALIGNMENT - 1) & ~(NEEDED_ALIGNMENT - 1);
1974 /* Chunk is small, register the rest for future allocs. */
1975 Perl_sbrk_oldchunk = got + reqsize;
1976 Perl_sbrk_oldsize = size - reqsize;
1980 DEBUG_m(PerlIO_printf(Perl_debug_log, "sbrk malloc size %ld (reqsize %ld), left size %ld, give addr 0x%"UVxf"\n",
1981 size, reqsize, Perl_sbrk_oldsize, PTR2UV(got)));
1986 #endif /* ! defined USE_PERL_SBRK */