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
131 # Maximal value in LONG
134 # Unsigned integer type big enough to keep a pointer
137 # Type of pointer with 1-byte granularity
140 # Type returned by free()
143 # Very fatal condition reporting function (cannot call any )
144 fatalcroak(arg) write(2,arg,strlen(arg)) + exit(2)
146 # Fatal error reporting function
147 croak(format, arg) warn(idem) + exit(1)
149 # Error reporting function
150 warn(format, arg) fprintf(stderr, idem)
152 # Locking/unlocking for MT operation
153 MALLOC_LOCK MUTEX_LOCK_NOCONTEXT(&PL_malloc_mutex)
154 MALLOC_UNLOCK MUTEX_UNLOCK_NOCONTEXT(&PL_malloc_mutex)
156 # Locking/unlocking mutex for MT operation
161 #ifndef NO_FANCY_MALLOC
162 # ifndef SMALL_BUCKET_VIA_TABLE
163 # define SMALL_BUCKET_VIA_TABLE
165 # ifndef BUCKETS_ROOT2
166 # define BUCKETS_ROOT2
168 # ifndef IGNORE_SMALL_BAD_FREE
169 # define IGNORE_SMALL_BAD_FREE
173 #ifndef PLAIN_MALLOC /* Bulk enable features */
177 # ifndef TWO_POT_OPTIMIZE
178 # define TWO_POT_OPTIMIZE
180 # if defined(PERL_CORE) && !defined(PERL_EMERGENCY_SBRK)
181 # define PERL_EMERGENCY_SBRK
183 # if defined(PERL_CORE) && !defined(DEBUGGING_MSTATS)
184 # define DEBUGGING_MSTATS
188 #define MIN_BUC_POW2 (sizeof(void*) > 4 ? 3 : 2) /* Allow for 4-byte arena. */
189 #define MIN_BUCKET (MIN_BUC_POW2 * BUCKETS_PER_POW2)
191 #if !(defined(I286) || defined(atarist) || defined(__MINT__))
192 /* take 2k unless the block is bigger than that */
193 # define LOG_OF_MIN_ARENA 11
195 /* take 16k unless the block is bigger than that
196 (80286s like large segments!), probably good on the atari too */
197 # define LOG_OF_MIN_ARENA 14
201 # if defined(DEBUGGING) && !defined(NO_RCHECK)
204 # if defined(RCHECK) && defined(IGNORE_SMALL_BAD_FREE)
205 # undef IGNORE_SMALL_BAD_FREE
208 * malloc.c (Caltech) 2/21/82
209 * Chris Kingsley, kingsley@cit-20.
211 * This is a very fast storage allocator. It allocates blocks of a small
212 * number of different sizes, and keeps free lists of each size. Blocks that
213 * don't exactly fit are passed up to the next larger size. In this
214 * implementation, the available sizes are 2^n-4 (or 2^n-12) bytes long.
215 * If PACK_MALLOC is defined, small blocks are 2^n bytes long.
216 * This is designed for use in a program that uses vast quantities of memory,
217 * but bombs when it runs out.
219 * Modifications Copyright Ilya Zakharevich 1996-99.
221 * Still very quick, but much more thrifty. (Std config is 10% slower
222 * than it was, and takes 67% of old heap size for typical usage.)
224 * Allocations of small blocks are now table-driven to many different
225 * buckets. Sizes of really big buckets are increased to accomodata
226 * common size=power-of-2 blocks. Running-out-of-memory is made into
227 * an exception. Deeply configurable and thread-safe.
233 # define PERL_IN_MALLOC_C
235 # if defined(PERL_IMPLICIT_CONTEXT)
236 # define croak Perl_croak_nocontext
237 # define warn Perl_warn_nocontext
241 # include "../EXTERN.h"
242 # include "../perl.h"
249 # define Malloc_t void *
255 # define MEM_SIZE unsigned long
258 # define LONG_MAX 0x7FFFFFFF
261 # define UV unsigned long
264 # define caddr_t char *
269 # define Copy(s,d,n,t) (void)memcpy((char*)(d),(char*)(s), (n) * sizeof(t))
270 # define PerlEnv_getenv getenv
271 # define PerlIO_printf fprintf
272 # define PerlIO_stderr() stderr
274 # ifndef croak /* make depend */
275 # define croak(mess, arg) (warn((mess), (arg)), exit(1))
278 # define warn(mess, arg) fprintf(stderr, (mess), (arg))
290 # define dTHX extern int Perl___notused
291 # define WITH_THX(s) s
293 # ifndef PERL_GET_INTERP
294 # define PERL_GET_INTERP PL_curinterp
297 # define Perl_malloc malloc
300 # define Perl_mfree free
302 # ifndef Perl_realloc
303 # define Perl_realloc realloc
306 # define Perl_calloc calloc
309 # define Perl_strdup strdup
314 # define MUTEX_LOCK(l)
318 # define MUTEX_UNLOCK(l)
322 # define MALLOC_LOCK MUTEX_LOCK_NOCONTEXT(&PL_malloc_mutex)
325 #ifndef MALLOC_UNLOCK
326 # define MALLOC_UNLOCK MUTEX_UNLOCK_NOCONTEXT(&PL_malloc_mutex)
329 # ifndef fatalcroak /* make depend */
330 # define fatalcroak(mess) (write(2, (mess), strlen(mess)), exit(2))
335 # define DEBUG_m(a) \
337 if (PERL_GET_INTERP) { dTHX; if (PL_debug & 128) { a; } } \
341 #ifdef PERL_IMPLICIT_CONTEXT
342 # define PERL_IS_ALIVE aTHX
344 # define PERL_IS_ALIVE TRUE
351 * The memory is broken into "blocks" which occupy multiples of 2K (and
352 * generally speaking, have size "close" to a power of 2). The addresses
353 * of such *unused* blocks are kept in nextf[i] with big enough i. (nextf
354 * is an array of linked lists.) (Addresses of used blocks are not known.)
356 * Moreover, since the algorithm may try to "bite" smaller blocks out
357 * of unused bigger ones, there are also regions of "irregular" size,
358 * managed separately, by a linked list chunk_chain.
360 * The third type of storage is the sbrk()ed-but-not-yet-used space, its
361 * end and size are kept in last_sbrk_top and sbrked_remains.
363 * Growing blocks "in place":
364 * ~~~~~~~~~~~~~~~~~~~~~~~~~
365 * The address of the block with the greatest address is kept in last_op
366 * (if not known, last_op is 0). If it is known that the memory above
367 * last_op is not continuous, or contains a chunk from chunk_chain,
368 * last_op is set to 0.
370 * The chunk with address last_op may be grown by expanding into
371 * sbrk()ed-but-not-yet-used space, or trying to sbrk() more continuous
374 * Management of last_op:
375 * ~~~~~~~~~~~~~~~~~~~~~
377 * free() never changes the boundaries of blocks, so is not relevant.
379 * The only way realloc() may change the boundaries of blocks is if it
380 * grows a block "in place". However, in the case of success such a
381 * chunk is automatically last_op, and it remains last_op. In the case
382 * of failure getpages_adjacent() clears last_op.
384 * malloc() may change blocks by calling morecore() only.
386 * morecore() may create new blocks by:
387 * a) biting pieces from chunk_chain (cannot create one above last_op);
388 * b) biting a piece from an unused block (if block was last_op, this
389 * may create a chunk from chain above last_op, thus last_op is
390 * invalidated in such a case).
391 * c) biting of sbrk()ed-but-not-yet-used space. This creates
392 * a block which is last_op.
393 * d) Allocating new pages by calling getpages();
395 * getpages() creates a new block. It marks last_op at the bottom of
396 * the chunk of memory it returns.
398 * Active pages footprint:
399 * ~~~~~~~~~~~~~~~~~~~~~~
400 * Note that we do not need to traverse the lists in nextf[i], just take
401 * the first element of this list. However, we *need* to traverse the
402 * list in chunk_chain, but most the time it should be a very short one,
403 * so we do not step on a lot of pages we are not going to use.
407 * get_from_bigger_buckets(): forget to increment price => Quite
411 /* I don't much care whether these are defined in sys/types.h--LAW */
413 #define u_char unsigned char
414 #define u_int unsigned int
416 * I removed the definition of u_bigint which appeared to be u_bigint = UV
417 * u_bigint was only used in TWOK_MASKED and TWOK_SHIFT
418 * where I have used PTR2UV. RMB
420 #define u_short unsigned short
422 /* 286 and atarist like big chunks, which gives too much overhead. */
423 #if (defined(RCHECK) || defined(I286) || defined(atarist) || defined(__MINT__)) && defined(PACK_MALLOC)
428 * The description below is applicable if PACK_MALLOC is not defined.
430 * The overhead on a block is at least 4 bytes. When free, this space
431 * contains a pointer to the next free block, and the bottom two bits must
432 * be zero. When in use, the first byte is set to MAGIC, and the second
433 * byte is the size index. The remaining bytes are for alignment.
434 * If range checking is enabled and the size of the block fits
435 * in two bytes, then the top two bytes hold the size of the requested block
436 * plus the range checking words, and the header word MINUS ONE.
439 union overhead *ov_next; /* when free */
440 #if MEM_ALIGNBYTES > 4
441 double strut; /* alignment problems */
444 u_char ovu_magic; /* magic number */
445 u_char ovu_index; /* bucket # */
447 u_short ovu_size; /* actual block size */
448 u_int ovu_rmagic; /* range magic number */
451 #define ov_magic ovu.ovu_magic
452 #define ov_index ovu.ovu_index
453 #define ov_size ovu.ovu_size
454 #define ov_rmagic ovu.ovu_rmagic
457 #define MAGIC 0xff /* magic # on accounting info */
458 #define RMAGIC 0x55555555 /* magic # on range info */
459 #define RMAGIC_C 0x55 /* magic # on range info */
462 # define RSLOP sizeof (u_int)
463 # ifdef TWO_POT_OPTIMIZE
464 # define MAX_SHORT_BUCKET (12 * BUCKETS_PER_POW2)
466 # define MAX_SHORT_BUCKET (13 * BUCKETS_PER_POW2)
472 #if !defined(PACK_MALLOC) && defined(BUCKETS_ROOT2)
473 # undef BUCKETS_ROOT2
477 # define BUCKET_TABLE_SHIFT 2
478 # define BUCKET_POW2_SHIFT 1
479 # define BUCKETS_PER_POW2 2
481 # define BUCKET_TABLE_SHIFT MIN_BUC_POW2
482 # define BUCKET_POW2_SHIFT 0
483 # define BUCKETS_PER_POW2 1
486 #if !defined(MEM_ALIGNBYTES) || ((MEM_ALIGNBYTES > 4) && !defined(STRICT_ALIGNMENT))
487 /* Figure out the alignment of void*. */
492 # define ALIGN_SMALL ((int)((caddr_t)&(((struct aligner*)0)->p)))
494 # define ALIGN_SMALL MEM_ALIGNBYTES
497 #define IF_ALIGN_8(yes,no) ((ALIGN_SMALL>4) ? (yes) : (no))
500 # define MAX_BUCKET_BY_TABLE 13
501 static u_short buck_size[MAX_BUCKET_BY_TABLE + 1] =
503 0, 0, 0, 0, 4, 4, 8, 12, 16, 24, 32, 48, 64, 80,
505 # define BUCKET_SIZE(i) ((i) % 2 ? buck_size[i] : (1 << ((i) >> BUCKET_POW2_SHIFT)))
506 # define BUCKET_SIZE_REAL(i) ((i) <= MAX_BUCKET_BY_TABLE \
508 : ((1 << ((i) >> BUCKET_POW2_SHIFT)) \
510 + POW2_OPTIMIZE_SURPLUS(i)))
512 # define BUCKET_SIZE(i) (1 << ((i) >> BUCKET_POW2_SHIFT))
513 # define BUCKET_SIZE_REAL(i) (BUCKET_SIZE(i) - MEM_OVERHEAD(i) + POW2_OPTIMIZE_SURPLUS(i))
518 /* In this case there are several possible layout of arenas depending
519 * on the size. Arenas are of sizes multiple to 2K, 2K-aligned, and
520 * have a size close to a power of 2.
522 * Arenas of the size >= 4K keep one chunk only. Arenas of size 2K
523 * may keep one chunk or multiple chunks. Here are the possible
526 * # One chunk only, chunksize 2^k + SOMETHING - ALIGN, k >= 11
528 * INDEX MAGIC1 UNUSED CHUNK1
530 * # Multichunk with sanity checking and chunksize 2^k-ALIGN, k>7
532 * INDEX MAGIC1 MAGIC2 MAGIC3 UNUSED CHUNK1 CHUNK2 CHUNK3 ...
534 * # Multichunk with sanity checking and size 2^k-ALIGN, k=7
536 * INDEX MAGIC1 MAGIC2 MAGIC3 UNUSED CHUNK1 UNUSED CHUNK2 CHUNK3 ...
538 * # Multichunk with sanity checking and size up to 80
540 * INDEX UNUSED MAGIC1 UNUSED MAGIC2 UNUSED ... CHUNK1 CHUNK2 CHUNK3 ...
542 * # No sanity check (usually up to 48=byte-long buckets)
543 * INDEX UNUSED CHUNK1 CHUNK2 ...
545 * Above INDEX and MAGIC are one-byte-long. Sizes of UNUSED are
546 * appropriate to keep algorithms simple and memory aligned. INDEX
547 * encodes the size of the chunk, while MAGICn encodes state (used,
548 * free or non-managed-by-us-so-it-indicates-a-bug) of CHUNKn. MAGIC
549 * is used for sanity checking purposes only. SOMETHING is 0 or 4K
550 * (to make size of big CHUNK accomodate allocations for powers of two
553 * [There is no need to alignment between chunks, since C rules ensure
554 * that structs which need 2^k alignment have sizeof which is
555 * divisible by 2^k. Thus as far as the last chunk is aligned at the
556 * end of the arena, and 2K-alignment does not contradict things,
557 * everything is going to be OK for sizes of chunks 2^n and 2^n +
558 * 2^k. Say, 80-bit buckets will be 16-bit aligned, and as far as we
559 * put allocations for requests in 65..80 range, all is fine.
561 * Note, however, that standard malloc() puts more strict
562 * requirements than the above C rules. Moreover, our algorithms of
563 * realloc() may break this idyll, but we suppose that realloc() does
564 * need not change alignment.]
566 * Is very important to make calculation of the offset of MAGICm as
567 * quick as possible, since it is done on each malloc()/free(). In
568 * fact it is so quick that it has quite little effect on the speed of
569 * doing malloc()/free(). [By default] We forego such calculations
570 * for small chunks, but only to save extra 3% of memory, not because
571 * of speed considerations.
573 * Here is the algorithm [which is the same for all the allocations
574 * schemes above], see OV_MAGIC(block,bucket). Let OFFSETm be the
575 * offset of the CHUNKm from the start of ARENA. Then offset of
576 * MAGICm is (OFFSET1 >> SHIFT) + ADDOFFSET. Here SHIFT and ADDOFFSET
577 * are numbers which depend on the size of the chunks only.
579 * Let as check some sanity conditions. Numbers OFFSETm>>SHIFT are
580 * different for all the chunks in the arena if 2^SHIFT is not greater
581 * than size of the chunks in the arena. MAGIC1 will not overwrite
582 * INDEX provided ADDOFFSET is >0 if OFFSET1 < 2^SHIFT. MAGIClast
583 * will not overwrite CHUNK1 if OFFSET1 > (OFFSETlast >> SHIFT) +
586 * Make SHIFT the maximal possible (there is no point in making it
587 * smaller). Since OFFSETlast is 2K - CHUNKSIZE, above restrictions
588 * give restrictions on OFFSET1 and on ADDOFFSET.
590 * In particular, for chunks of size 2^k with k>=6 we can put
591 * ADDOFFSET to be from 0 to 2^k - 2^(11-k), and have
592 * OFFSET1==chunksize. For chunks of size 80 OFFSET1 of 2K%80=48 is
593 * large enough to have ADDOFFSET between 1 and 16 (similarly for 96,
594 * when ADDOFFSET should be 1). In particular, keeping MAGICs for
595 * these sizes gives no additional size penalty.
597 * However, for chunks of size 2^k with k<=5 this gives OFFSET1 >=
598 * ADDOFSET + 2^(11-k). Keeping ADDOFFSET 0 allows for 2^(11-k)-2^(11-2k)
599 * chunks per arena. This is smaller than 2^(11-k) - 1 which are
600 * needed if no MAGIC is kept. [In fact, having a negative ADDOFFSET
601 * would allow for slightly more buckets per arena for k=2,3.]
603 * Similarly, for chunks of size 3/2*2^k with k<=5 MAGICs would span
604 * the area up to 2^(11-k)+ADDOFFSET. For k=4 this give optimal
605 * ADDOFFSET as -7..0. For k=3 ADDOFFSET can go up to 4 (with tiny
606 * savings for negative ADDOFFSET). For k=5 ADDOFFSET can go -1..16
607 * (with no savings for negative values).
609 * In particular, keeping ADDOFFSET 0 for sizes of chunks up to 2^6
610 * leads to tiny pessimizations in case of sizes 4, 8, 12, 24, and
611 * leads to no contradictions except for size=80 (or 96.)
613 * However, it also makes sense to keep no magic for sizes 48 or less.
614 * This is what we do. In this case one needs ADDOFFSET>=1 also for
615 * chunksizes 12, 24, and 48, unless one gets one less chunk per
618 * The algo of OV_MAGIC(block,bucket) keeps ADDOFFSET 0 until
619 * chunksize of 64, then makes it 1.
621 * This allows for an additional optimization: the above scheme leads
622 * to giant overheads for sizes 128 or more (one whole chunk needs to
623 * be sacrifised to keep INDEX). Instead we use chunks not of size
624 * 2^k, but of size 2^k-ALIGN. If we pack these chunks at the end of
625 * the arena, then the beginnings are still in different 2^k-long
626 * sections of the arena if k>=7 for ALIGN==4, and k>=8 if ALIGN=8.
627 * Thus for k>7 the above algo of calculating the offset of the magic
628 * will still give different answers for different chunks. And to
629 * avoid the overrun of MAGIC1 into INDEX, one needs ADDOFFSET of >=1.
630 * In the case k=7 we just move the first chunk an extra ALIGN
631 * backward inside the ARENA (this is done once per arena lifetime,
632 * thus is not a big overhead). */
633 # define MAX_PACKED_POW2 6
634 # define MAX_PACKED (MAX_PACKED_POW2 * BUCKETS_PER_POW2 + BUCKET_POW2_SHIFT)
635 # define MAX_POW2_ALGO ((1<<(MAX_PACKED_POW2 + 1)) - M_OVERHEAD)
636 # define TWOK_MASK ((1<<LOG_OF_MIN_ARENA) - 1)
637 # define TWOK_MASKED(x) (PTR2UV(x) & ~TWOK_MASK)
638 # define TWOK_SHIFT(x) (PTR2UV(x) & TWOK_MASK)
639 # define OV_INDEXp(block) (INT2PTR(u_char*,TWOK_MASKED(block)))
640 # define OV_INDEX(block) (*OV_INDEXp(block))
641 # define OV_MAGIC(block,bucket) (*(OV_INDEXp(block) + \
642 (TWOK_SHIFT(block)>> \
643 (bucket>>BUCKET_POW2_SHIFT)) + \
644 (bucket >= MIN_NEEDS_SHIFT ? 1 : 0)))
645 /* A bucket can have a shift smaller than it size, we need to
646 shift its magic number so it will not overwrite index: */
647 # ifdef BUCKETS_ROOT2
648 # define MIN_NEEDS_SHIFT (7*BUCKETS_PER_POW2 - 1) /* Shift 80 greater than chunk 64. */
650 # define MIN_NEEDS_SHIFT (7*BUCKETS_PER_POW2) /* Shift 128 greater than chunk 32. */
652 # define CHUNK_SHIFT 0
654 /* Number of active buckets of given ordinal. */
655 #ifdef IGNORE_SMALL_BAD_FREE
656 #define FIRST_BUCKET_WITH_CHECK (6 * BUCKETS_PER_POW2) /* 64 */
657 # define N_BLKS(bucket) ( (bucket) < FIRST_BUCKET_WITH_CHECK \
658 ? ((1<<LOG_OF_MIN_ARENA) - 1)/BUCKET_SIZE(bucket) \
661 # define N_BLKS(bucket) n_blks[bucket]
664 static u_short n_blks[LOG_OF_MIN_ARENA * BUCKETS_PER_POW2] =
666 # if BUCKETS_PER_POW2==1
668 (MIN_BUC_POW2==2 ? 384 : 0),
669 224, 120, 62, 31, 16, 8, 4, 2
672 (MIN_BUC_POW2==2 ? 384 : 0), (MIN_BUC_POW2==2 ? 384 : 0), /* 4, 4 */
673 224, 149, 120, 80, 62, 41, 31, 25, 16, 16, 8, 8, 4, 4, 2, 2
677 /* Shift of the first bucket with the given ordinal inside 2K chunk. */
678 #ifdef IGNORE_SMALL_BAD_FREE
679 # define BLK_SHIFT(bucket) ( (bucket) < FIRST_BUCKET_WITH_CHECK \
680 ? ((1<<LOG_OF_MIN_ARENA) \
681 - BUCKET_SIZE(bucket) * N_BLKS(bucket)) \
684 # define BLK_SHIFT(bucket) blk_shift[bucket]
687 static u_short blk_shift[LOG_OF_MIN_ARENA * BUCKETS_PER_POW2] =
689 # if BUCKETS_PER_POW2==1
691 (MIN_BUC_POW2==2 ? 512 : 0),
692 256, 128, 64, 64, /* 8 to 64 */
693 16*sizeof(union overhead),
694 8*sizeof(union overhead),
695 4*sizeof(union overhead),
696 2*sizeof(union overhead),
699 (MIN_BUC_POW2==2 ? 512 : 0), (MIN_BUC_POW2==2 ? 512 : 0),
700 256, 260, 128, 128, 64, 80, 64, 48, /* 8 to 96 */
701 16*sizeof(union overhead), 16*sizeof(union overhead),
702 8*sizeof(union overhead), 8*sizeof(union overhead),
703 4*sizeof(union overhead), 4*sizeof(union overhead),
704 2*sizeof(union overhead), 2*sizeof(union overhead),
708 # define NEEDED_ALIGNMENT 0x800 /* 2k boundaries */
709 # define WANTED_ALIGNMENT 0x800 /* 2k boundaries */
711 #else /* !PACK_MALLOC */
713 # define OV_MAGIC(block,bucket) (block)->ov_magic
714 # define OV_INDEX(block) (block)->ov_index
715 # define CHUNK_SHIFT 1
716 # define MAX_PACKED -1
717 # define NEEDED_ALIGNMENT MEM_ALIGNBYTES
718 # define WANTED_ALIGNMENT 0x400 /* 1k boundaries */
720 #endif /* !PACK_MALLOC */
722 #define M_OVERHEAD (sizeof(union overhead) + RSLOP)
725 # define MEM_OVERHEAD(bucket) \
726 (bucket <= MAX_PACKED ? 0 : M_OVERHEAD)
727 # ifdef SMALL_BUCKET_VIA_TABLE
728 # define START_SHIFTS_BUCKET ((MAX_PACKED_POW2 + 1) * BUCKETS_PER_POW2)
729 # define START_SHIFT MAX_PACKED_POW2
730 # ifdef BUCKETS_ROOT2 /* Chunks of size 3*2^n. */
731 # define SIZE_TABLE_MAX 80
733 # define SIZE_TABLE_MAX 64
735 static char bucket_of[] =
737 # ifdef BUCKETS_ROOT2 /* Chunks of size 3*2^n. */
738 /* 0 to 15 in 4-byte increments. */
739 (sizeof(void*) > 4 ? 6 : 5), /* 4/8, 5-th bucket for better reports */
741 IF_ALIGN_8(8,7), 8, /* 16/12, 16 */
742 9, 9, 10, 10, /* 24, 32 */
743 11, 11, 11, 11, /* 48 */
744 12, 12, 12, 12, /* 64 */
745 13, 13, 13, 13, /* 80 */
746 13, 13, 13, 13 /* 80 */
747 # else /* !BUCKETS_ROOT2 */
748 /* 0 to 15 in 4-byte increments. */
749 (sizeof(void*) > 4 ? 3 : 2),
755 # endif /* !BUCKETS_ROOT2 */
757 # else /* !SMALL_BUCKET_VIA_TABLE */
758 # define START_SHIFTS_BUCKET MIN_BUCKET
759 # define START_SHIFT (MIN_BUC_POW2 - 1)
760 # endif /* !SMALL_BUCKET_VIA_TABLE */
761 #else /* !PACK_MALLOC */
762 # define MEM_OVERHEAD(bucket) M_OVERHEAD
763 # ifdef SMALL_BUCKET_VIA_TABLE
764 # undef SMALL_BUCKET_VIA_TABLE
766 # define START_SHIFTS_BUCKET MIN_BUCKET
767 # define START_SHIFT (MIN_BUC_POW2 - 1)
768 #endif /* !PACK_MALLOC */
771 * Big allocations are often of the size 2^n bytes. To make them a
772 * little bit better, make blocks of size 2^n+pagesize for big n.
775 #ifdef TWO_POT_OPTIMIZE
777 # ifndef PERL_PAGESIZE
778 # define PERL_PAGESIZE 4096
780 # ifndef FIRST_BIG_POW2
781 # define FIRST_BIG_POW2 15 /* 32K, 16K is used too often. */
783 # define FIRST_BIG_BLOCK (1<<FIRST_BIG_POW2)
784 /* If this value or more, check against bigger blocks. */
785 # define FIRST_BIG_BOUND (FIRST_BIG_BLOCK - M_OVERHEAD)
786 /* If less than this value, goes into 2^n-overhead-block. */
787 # define LAST_SMALL_BOUND ((FIRST_BIG_BLOCK>>1) - M_OVERHEAD)
789 # define POW2_OPTIMIZE_ADJUST(nbytes) \
790 ((nbytes >= FIRST_BIG_BOUND) ? nbytes -= PERL_PAGESIZE : 0)
791 # define POW2_OPTIMIZE_SURPLUS(bucket) \
792 ((bucket >= FIRST_BIG_POW2 * BUCKETS_PER_POW2) ? PERL_PAGESIZE : 0)
794 #else /* !TWO_POT_OPTIMIZE */
795 # define POW2_OPTIMIZE_ADJUST(nbytes)
796 # define POW2_OPTIMIZE_SURPLUS(bucket) 0
797 #endif /* !TWO_POT_OPTIMIZE */
799 #if defined(HAS_64K_LIMIT) && defined(PERL_CORE)
800 # define BARK_64K_LIMIT(what,nbytes,size) \
801 if (nbytes > 0xffff) { \
802 PerlIO_printf(PerlIO_stderr(), \
803 "%s too large: %lx\n", what, size); \
806 #else /* !HAS_64K_LIMIT || !PERL_CORE */
807 # define BARK_64K_LIMIT(what,nbytes,size)
808 #endif /* !HAS_64K_LIMIT || !PERL_CORE */
811 # define MIN_SBRK 2048
815 # define FIRST_SBRK (48*1024)
818 /* Minimal sbrk in percents of what is already alloced. */
819 #ifndef MIN_SBRK_FRAC
820 # define MIN_SBRK_FRAC 3
823 #ifndef SBRK_ALLOW_FAILURES
824 # define SBRK_ALLOW_FAILURES 3
827 #ifndef SBRK_FAILURE_PRICE
828 # define SBRK_FAILURE_PRICE 50
831 #if defined(PERL_EMERGENCY_SBRK) && defined(PERL_CORE)
834 # define BIG_SIZE (1<<16) /* 64K */
837 #ifdef I_MACH_CTHREADS
839 # define MUTEX_LOCK(m) STMT_START { if (*m) mutex_lock(*m); } STMT_END
841 # define MUTEX_UNLOCK(m) STMT_START { if (*m) mutex_unlock(*m); } STMT_END
844 static char *emergency_buffer;
845 static MEM_SIZE emergency_buffer_size;
847 static void morecore (register int bucket);
848 # if defined(DEBUGGING)
849 static void botch (char *diag, char *s);
851 static void add_to_chain (void *p, MEM_SIZE size, MEM_SIZE chip);
852 static Malloc_t emergency_sbrk (MEM_SIZE size);
853 static void* get_from_chain (MEM_SIZE size);
854 static void* get_from_bigger_buckets(int bucket, MEM_SIZE size);
855 static union overhead *getpages (MEM_SIZE needed, int *nblksp, int bucket);
856 static int getpages_adjacent(MEM_SIZE require);
859 emergency_sbrk(MEM_SIZE size)
861 MEM_SIZE rsize = (((size - 1)>>LOG_OF_MIN_ARENA) + 1)<<LOG_OF_MIN_ARENA;
863 if (size >= BIG_SIZE) {
864 /* Give the possibility to recover: */
866 croak("Out of memory during \"large\" request for %i bytes", size);
869 if (emergency_buffer_size >= rsize) {
870 char *old = emergency_buffer;
872 emergency_buffer_size -= rsize;
873 emergency_buffer += rsize;
877 /* First offense, give a possibility to recover by dieing. */
878 /* No malloc involved here: */
879 GV **gvp = (GV**)hv_fetch(PL_defstash, "^M", 2, 0);
885 if (emergency_buffer_size) {
886 add_to_chain(emergency_buffer, emergency_buffer_size, 0);
887 emergency_buffer_size = 0;
888 emergency_buffer = Nullch;
891 if (!gvp) gvp = (GV**)hv_fetch(PL_defstash, "\015", 1, 0);
892 if (!gvp || !(sv = GvSV(*gvp)) || !SvPOK(sv)
893 || (SvLEN(sv) < (1<<LOG_OF_MIN_ARENA) - M_OVERHEAD)) {
896 return (char *)-1; /* Now die die die... */
898 /* Got it, now detach SvPV: */
900 /* Check alignment: */
901 if ((PTR2UV(pv) - sizeof(union overhead)) & (NEEDED_ALIGNMENT - 1)) {
902 PerlIO_puts(PerlIO_stderr(),"Bad alignment of $^M!\n");
903 return (char *)-1; /* die die die */
906 emergency_buffer = pv - sizeof(union overhead);
907 emergency_buffer_size = malloced_size(pv) + M_OVERHEAD;
910 SvCUR(sv) = SvLEN(sv) = 0;
914 croak("Out of memory during request for %i bytes", size);
919 #else /* !(defined(PERL_EMERGENCY_SBRK) && defined(PERL_CORE)) */
920 # define emergency_sbrk(size) -1
921 #endif /* !(defined(PERL_EMERGENCY_SBRK) && defined(PERL_CORE)) */
924 # define BITS_IN_PTR (8*PTRSIZE)
928 * nextf[i] is the pointer to the next free block of size 2^i. The
929 * smallest allocatable block is 8 bytes. The overhead information
930 * precedes the data area returned to the user.
932 #define NBUCKETS (BITS_IN_PTR*BUCKETS_PER_POW2 + 1)
933 static union overhead *nextf[NBUCKETS];
935 #if defined(PURIFY) && !defined(USE_PERL_SBRK)
936 # define USE_PERL_SBRK
940 #define sbrk(a) Perl_sbrk(a)
941 Malloc_t Perl_sbrk (int size);
943 #ifdef DONT_DECLARE_STD
948 extern Malloc_t sbrk(int);
952 #ifdef DEBUGGING_MSTATS
954 * nmalloc[i] is the difference between the number of mallocs and frees
955 * for a given block size.
957 static u_int nmalloc[NBUCKETS];
958 static u_int sbrk_slack;
959 static u_int start_slack;
962 static u_int goodsbrk;
966 #define ASSERT(p,diag) if (!(p)) botch(diag,STRINGIFY(p)); else
968 botch(char *diag, char *s)
971 PerlIO_printf(PerlIO_stderr(), "assertion botched (%s?): %s\n", diag, s);
975 #define ASSERT(p, diag)
979 Perl_malloc(register size_t nbytes)
981 register union overhead *p;
983 register MEM_SIZE shiftr;
984 static void morecore(int bucket);
986 #if defined(DEBUGGING) || defined(RCHECK)
987 MEM_SIZE size = nbytes;
990 BARK_64K_LIMIT("Allocation",nbytes,nbytes);
992 if ((long)nbytes < 0)
993 croak("%s", "panic: malloc");
997 * Convert amount of memory requested into
998 * closest block size stored in hash buckets
999 * which satisfies request. Account for
1000 * space used per block for accounting.
1003 # ifdef SMALL_BUCKET_VIA_TABLE
1005 bucket = MIN_BUCKET;
1006 else if (nbytes <= SIZE_TABLE_MAX) {
1007 bucket = bucket_of[(nbytes - 1) >> BUCKET_TABLE_SHIFT];
1012 if (nbytes <= MAX_POW2_ALGO) goto do_shifts;
1017 POW2_OPTIMIZE_ADJUST(nbytes);
1018 nbytes += M_OVERHEAD;
1019 nbytes = (nbytes + 3) &~ 3;
1021 shiftr = (nbytes - 1) >> START_SHIFT;
1022 bucket = START_SHIFTS_BUCKET;
1023 /* apart from this loop, this is O(1) */
1024 while (shiftr >>= 1)
1025 bucket += BUCKETS_PER_POW2;
1029 * If nothing in hash bucket right now,
1030 * request more memory from the system.
1032 if (nextf[bucket] == NULL)
1034 if ((p = nextf[bucket]) == NULL) {
1040 PerlIO_puts(PerlIO_stderr(),"Out of memory!\n");
1048 DEBUG_m(PerlIO_printf(Perl_debug_log,
1049 "0x%"UVxf": (%05lu) malloc %ld bytes\n",
1050 PTR2UV(p+1), (unsigned long)(PL_an++),
1053 /* remove from linked list */
1055 if ((PTR2UV(p)) & (MEM_ALIGNBYTES - 1)) {
1057 PerlIO_printf(PerlIO_stderr(),
1058 "Unaligned pointer in the free chain 0x%"UVxf"\n",
1061 if ((PTR2UV(p->ov_next)) & (MEM_ALIGNBYTES - 1)) {
1063 PerlIO_printf(PerlIO_stderr(),
1064 "Unaligned `next' pointer in the free "
1065 "chain 0x"UVxf" at 0x%"UVxf"\n",
1066 PTR2UV(p->ov_next), PTR2UV(p));
1069 nextf[bucket] = p->ov_next;
1073 #ifdef IGNORE_SMALL_BAD_FREE
1074 if (bucket >= FIRST_BUCKET_WITH_CHECK)
1076 OV_MAGIC(p, bucket) = MAGIC;
1078 OV_INDEX(p) = bucket;
1082 * Record allocated size of block and
1083 * bound space with magic numbers.
1085 p->ov_rmagic = RMAGIC;
1086 if (bucket <= MAX_SHORT_BUCKET) {
1089 nbytes = size + M_OVERHEAD;
1090 p->ov_size = nbytes - 1;
1091 if ((i = nbytes & 3)) {
1094 *((char *)((caddr_t)p + nbytes - RSLOP + i)) = RMAGIC_C;
1096 nbytes = (nbytes + 3) &~ 3;
1097 *((u_int *)((caddr_t)p + nbytes - RSLOP)) = RMAGIC;
1100 return ((Malloc_t)(p + CHUNK_SHIFT));
1103 static char *last_sbrk_top;
1104 static char *last_op; /* This arena can be easily extended. */
1105 static int sbrked_remains;
1106 static int sbrk_good = SBRK_ALLOW_FAILURES * SBRK_FAILURE_PRICE;
1108 #ifdef DEBUGGING_MSTATS
1112 struct chunk_chain_s {
1113 struct chunk_chain_s *next;
1116 static struct chunk_chain_s *chunk_chain;
1117 static int n_chunks;
1118 static char max_bucket;
1120 /* Cutoff a piece of one of the chunks in the chain. Prefer smaller chunk. */
1122 get_from_chain(MEM_SIZE size)
1124 struct chunk_chain_s *elt = chunk_chain, **oldp = &chunk_chain;
1125 struct chunk_chain_s **oldgoodp = NULL;
1126 long min_remain = LONG_MAX;
1129 if (elt->size >= size) {
1130 long remains = elt->size - size;
1131 if (remains >= 0 && remains < min_remain) {
1133 min_remain = remains;
1139 oldp = &( elt->next );
1142 if (!oldgoodp) return NULL;
1144 void *ret = *oldgoodp;
1145 struct chunk_chain_s *next = (*oldgoodp)->next;
1147 *oldgoodp = (struct chunk_chain_s *)((char*)ret + size);
1148 (*oldgoodp)->size = min_remain;
1149 (*oldgoodp)->next = next;
1152 void *ret = *oldgoodp;
1153 *oldgoodp = (*oldgoodp)->next;
1160 add_to_chain(void *p, MEM_SIZE size, MEM_SIZE chip)
1162 struct chunk_chain_s *next = chunk_chain;
1163 char *cp = (char*)p;
1166 chunk_chain = (struct chunk_chain_s *)cp;
1167 chunk_chain->size = size - chip;
1168 chunk_chain->next = next;
1173 get_from_bigger_buckets(int bucket, MEM_SIZE size)
1176 static int bucketprice[NBUCKETS];
1177 while (bucket <= max_bucket) {
1178 /* We postpone stealing from bigger buckets until we want it
1180 if (nextf[bucket] && bucketprice[bucket]++ >= price) {
1182 void *ret = (void*)(nextf[bucket] - 1 + CHUNK_SHIFT);
1183 bucketprice[bucket] = 0;
1184 if (((char*)nextf[bucket]) - M_OVERHEAD == last_op) {
1185 last_op = NULL; /* Disable optimization */
1187 nextf[bucket] = nextf[bucket]->ov_next;
1188 #ifdef DEBUGGING_MSTATS
1190 start_slack -= M_OVERHEAD;
1192 add_to_chain(ret, (BUCKET_SIZE(bucket) +
1193 POW2_OPTIMIZE_SURPLUS(bucket)),
1202 static union overhead *
1203 getpages(MEM_SIZE needed, int *nblksp, int bucket)
1205 /* Need to do (possibly expensive) system call. Try to
1206 optimize it for rare calling. */
1207 MEM_SIZE require = needed - sbrked_remains;
1209 union overhead *ovp;
1212 if (sbrk_good > 0) {
1213 if (!last_sbrk_top && require < FIRST_SBRK)
1214 require = FIRST_SBRK;
1215 else if (require < MIN_SBRK) require = MIN_SBRK;
1217 if (require < goodsbrk * MIN_SBRK_FRAC / 100)
1218 require = goodsbrk * MIN_SBRK_FRAC / 100;
1219 require = ((require - 1 + MIN_SBRK) / MIN_SBRK) * MIN_SBRK;
1226 DEBUG_m(PerlIO_printf(Perl_debug_log,
1227 "sbrk(%ld) for %ld-byte-long arena\n",
1228 (long)require, (long) needed));
1229 cp = (char *)sbrk(require);
1230 #ifdef DEBUGGING_MSTATS
1233 if (cp == last_sbrk_top) {
1234 /* Common case, anything is fine. */
1236 ovp = (union overhead *) (cp - sbrked_remains);
1237 last_op = cp - sbrked_remains;
1238 sbrked_remains = require - (needed - sbrked_remains);
1239 } else if (cp == (char *)-1) { /* no more room! */
1240 ovp = (union overhead *)emergency_sbrk(needed);
1241 if (ovp == (union overhead *)-1)
1243 if (((char*)ovp) > last_op) { /* Cannot happen with current emergency_sbrk() */
1247 } else { /* Non-continuous or first sbrk(). */
1248 long add = sbrked_remains;
1251 if (sbrked_remains) { /* Put rest into chain, we
1252 cannot use it right now. */
1253 add_to_chain((void*)(last_sbrk_top - sbrked_remains),
1257 /* Second, check alignment. */
1260 #if !defined(atarist) && !defined(__MINT__) /* on the atari we dont have to worry about this */
1261 # ifndef I286 /* The sbrk(0) call on the I286 always returns the next segment */
1262 /* WANTED_ALIGNMENT may be more than NEEDED_ALIGNMENT, but this may
1263 improve performance of memory access. */
1264 if (PTR2UV(cp) & (WANTED_ALIGNMENT - 1)) { /* Not aligned. */
1265 slack = WANTED_ALIGNMENT - (PTR2UV(cp) & (WANTED_ALIGNMENT - 1));
1269 #endif /* !atarist && !MINT */
1272 DEBUG_m(PerlIO_printf(Perl_debug_log,
1273 "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",
1274 (long)add, (long) slack,
1275 (long) sbrked_remains));
1276 newcp = (char *)sbrk(add);
1277 #if defined(DEBUGGING_MSTATS)
1281 if (newcp != cp + require) {
1282 /* Too bad: even rounding sbrk() is not continuous.*/
1283 DEBUG_m(PerlIO_printf(Perl_debug_log,
1284 "failed to fix bad sbrk()\n"));
1288 fatalcroak("panic: Off-page sbrk\n");
1291 if (sbrked_remains) {
1293 #if defined(DEBUGGING_MSTATS)
1294 sbrk_slack += require;
1297 DEBUG_m(PerlIO_printf(Perl_debug_log,
1298 "straight sbrk(%ld)\n",
1300 cp = (char *)sbrk(require);
1301 #ifdef DEBUGGING_MSTATS
1304 if (cp == (char *)-1)
1307 sbrk_good = -1; /* Disable optimization!
1308 Continue with not-aligned... */
1311 require += sbrked_remains;
1315 if (last_sbrk_top) {
1316 sbrk_good -= SBRK_FAILURE_PRICE;
1319 ovp = (union overhead *) cp;
1321 * Round up to minimum allocation size boundary
1322 * and deduct from block count to reflect.
1325 # if NEEDED_ALIGNMENT > MEM_ALIGNBYTES
1326 if (PTR2UV(ovp) & (NEEDED_ALIGNMENT - 1))
1327 fatalcroak("Misalignment of sbrk()\n");
1330 #ifndef I286 /* Again, this should always be ok on an 80286 */
1331 if (PTR2UV(ovp) & (MEM_ALIGNBYTES - 1)) {
1332 DEBUG_m(PerlIO_printf(Perl_debug_log,
1333 "fixing sbrk(): %d bytes off machine alignement\n",
1334 (int)(PTR2UV(ovp) & (MEM_ALIGNBYTES - 1))));
1335 ovp = INT2PTR(union overhead *,(PTR2UV(ovp) + MEM_ALIGNBYTES) &
1336 (MEM_ALIGNBYTES - 1));
1338 # if defined(DEBUGGING_MSTATS)
1339 /* This is only approx. if TWO_POT_OPTIMIZE: */
1340 sbrk_slack += (1 << (bucket >> BUCKET_POW2_SHIFT));
1344 ; /* Finish `else' */
1345 sbrked_remains = require - needed;
1348 last_sbrk_top = cp + require;
1349 #ifdef DEBUGGING_MSTATS
1350 goodsbrk += require;
1356 getpages_adjacent(MEM_SIZE require)
1358 if (require <= sbrked_remains) {
1359 sbrked_remains -= require;
1363 require -= sbrked_remains;
1364 /* We do not try to optimize sbrks here, we go for place. */
1365 cp = (char*) sbrk(require);
1366 #ifdef DEBUGGING_MSTATS
1368 goodsbrk += require;
1370 if (cp == last_sbrk_top) {
1372 last_sbrk_top = cp + require;
1374 if (cp == (char*)-1) { /* Out of memory */
1375 #ifdef DEBUGGING_MSTATS
1376 goodsbrk -= require;
1380 /* Report the failure: */
1382 add_to_chain((void*)(last_sbrk_top - sbrked_remains),
1384 add_to_chain((void*)cp, require, 0);
1385 sbrk_good -= SBRK_FAILURE_PRICE;
1397 * Allocate more memory to the indicated bucket.
1400 morecore(register int bucket)
1402 register union overhead *ovp;
1403 register int rnu; /* 2^rnu bytes will be requested */
1404 int nblks; /* become nblks blocks of the desired size */
1405 register MEM_SIZE siz, needed;
1409 if (bucket == sizeof(MEM_SIZE)*8*BUCKETS_PER_POW2) {
1411 croak("%s", "Out of memory during ridiculously large request");
1413 if (bucket > max_bucket)
1414 max_bucket = bucket;
1416 rnu = ( (bucket <= (LOG_OF_MIN_ARENA << BUCKET_POW2_SHIFT))
1418 : (bucket >> BUCKET_POW2_SHIFT) );
1419 /* This may be overwritten later: */
1420 nblks = 1 << (rnu - (bucket >> BUCKET_POW2_SHIFT)); /* how many blocks to get */
1421 needed = ((MEM_SIZE)1 << rnu) + POW2_OPTIMIZE_SURPLUS(bucket);
1422 if (nextf[rnu << BUCKET_POW2_SHIFT]) { /* 2048b bucket. */
1423 ovp = nextf[rnu << BUCKET_POW2_SHIFT] - 1 + CHUNK_SHIFT;
1424 nextf[rnu << BUCKET_POW2_SHIFT]
1425 = nextf[rnu << BUCKET_POW2_SHIFT]->ov_next;
1426 #ifdef DEBUGGING_MSTATS
1427 nmalloc[rnu << BUCKET_POW2_SHIFT]--;
1428 start_slack -= M_OVERHEAD;
1430 DEBUG_m(PerlIO_printf(Perl_debug_log,
1431 "stealing %ld bytes from %ld arena\n",
1432 (long) needed, (long) rnu << BUCKET_POW2_SHIFT));
1433 } else if (chunk_chain
1434 && (ovp = (union overhead*) get_from_chain(needed))) {
1435 DEBUG_m(PerlIO_printf(Perl_debug_log,
1436 "stealing %ld bytes from chain\n",
1438 } else if ( (ovp = (union overhead*)
1439 get_from_bigger_buckets((rnu << BUCKET_POW2_SHIFT) + 1,
1441 DEBUG_m(PerlIO_printf(Perl_debug_log,
1442 "stealing %ld bytes from bigger buckets\n",
1444 } else if (needed <= sbrked_remains) {
1445 ovp = (union overhead *)(last_sbrk_top - sbrked_remains);
1446 sbrked_remains -= needed;
1447 last_op = (char*)ovp;
1449 ovp = getpages(needed, &nblks, bucket);
1455 * Add new memory allocated to that on
1456 * free list for this hash bucket.
1458 siz = BUCKET_SIZE(bucket);
1460 *(u_char*)ovp = bucket; /* Fill index. */
1461 if (bucket <= MAX_PACKED) {
1462 ovp = (union overhead *) ((char*)ovp + BLK_SHIFT(bucket));
1463 nblks = N_BLKS(bucket);
1464 # ifdef DEBUGGING_MSTATS
1465 start_slack += BLK_SHIFT(bucket);
1467 } else if (bucket < LOG_OF_MIN_ARENA * BUCKETS_PER_POW2) {
1468 ovp = (union overhead *) ((char*)ovp + BLK_SHIFT(bucket));
1469 siz -= sizeof(union overhead);
1470 } else ovp++; /* One chunk per block. */
1471 #endif /* PACK_MALLOC */
1472 nextf[bucket] = ovp;
1473 #ifdef DEBUGGING_MSTATS
1474 nmalloc[bucket] += nblks;
1475 if (bucket > MAX_PACKED) {
1476 start_slack += M_OVERHEAD * nblks;
1479 while (--nblks > 0) {
1480 ovp->ov_next = (union overhead *)((caddr_t)ovp + siz);
1481 ovp = (union overhead *)((caddr_t)ovp + siz);
1483 /* Not all sbrks return zeroed memory.*/
1484 ovp->ov_next = (union overhead *)NULL;
1486 if (bucket == 7*BUCKETS_PER_POW2) { /* Special case, explanation is above. */
1487 union overhead *n_op = nextf[7*BUCKETS_PER_POW2]->ov_next;
1488 nextf[7*BUCKETS_PER_POW2] =
1489 (union overhead *)((caddr_t)nextf[7*BUCKETS_PER_POW2]
1490 - sizeof(union overhead));
1491 nextf[7*BUCKETS_PER_POW2]->ov_next = n_op;
1493 #endif /* !PACK_MALLOC */
1497 Perl_mfree(void *mp)
1499 register MEM_SIZE size;
1500 register union overhead *ovp;
1501 char *cp = (char*)mp;
1506 DEBUG_m(PerlIO_printf(Perl_debug_log,
1507 "0x%"UVxf": (%05lu) free\n",
1508 PTR2UV(cp), (unsigned long)(PL_an++)));
1512 ovp = (union overhead *)((caddr_t)cp
1513 - sizeof (union overhead) * CHUNK_SHIFT);
1515 bucket = OV_INDEX(ovp);
1517 #ifdef IGNORE_SMALL_BAD_FREE
1518 if ((bucket >= FIRST_BUCKET_WITH_CHECK)
1519 && (OV_MAGIC(ovp, bucket) != MAGIC))
1521 if (OV_MAGIC(ovp, bucket) != MAGIC)
1524 static int bad_free_warn = -1;
1525 if (bad_free_warn == -1) {
1527 char *pbf = PerlEnv_getenv("PERL_BADFREE");
1528 bad_free_warn = (pbf) ? atoi(pbf) : 1;
1536 if (!PERL_IS_ALIVE || !PL_curcop || ckWARN_d(WARN_MALLOC))
1537 Perl_warner(aTHX_ WARN_MALLOC, "%s free() ignored",
1538 ovp->ov_rmagic == RMAGIC - 1 ?
1539 "Duplicate" : "Bad");
1542 warn("%s free() ignored",
1543 ovp->ov_rmagic == RMAGIC - 1 ? "Duplicate" : "Bad");
1549 if (!PERL_IS_ALIVE || !PL_curcop || ckWARN_d(WARN_MALLOC))
1550 Perl_warner(aTHX_ WARN_MALLOC, "%s", "Bad free() ignored");
1553 warn("%s", "Bad free() ignored");
1556 return; /* sanity */
1559 ASSERT(ovp->ov_rmagic == RMAGIC, "chunk's head overwrite");
1560 if (OV_INDEX(ovp) <= MAX_SHORT_BUCKET) {
1562 MEM_SIZE nbytes = ovp->ov_size + 1;
1564 if ((i = nbytes & 3)) {
1567 ASSERT(*((char *)((caddr_t)ovp + nbytes - RSLOP + i))
1568 == RMAGIC_C, "chunk's tail overwrite");
1571 nbytes = (nbytes + 3) &~ 3;
1572 ASSERT(*(u_int *)((caddr_t)ovp + nbytes - RSLOP) == RMAGIC, "chunk's tail overwrite");
1574 ovp->ov_rmagic = RMAGIC - 1;
1576 ASSERT(OV_INDEX(ovp) < NBUCKETS, "chunk's head overwrite");
1577 size = OV_INDEX(ovp);
1580 ovp->ov_next = nextf[size];
1585 /* There is no need to do any locking in realloc (with an exception of
1586 trying to grow in place if we are at the end of the chain).
1587 If somebody calls us from a different thread with the same address,
1588 we are sole anyway. */
1591 Perl_realloc(void *mp, size_t nbytes)
1593 register MEM_SIZE onb;
1594 union overhead *ovp;
1597 register int bucket;
1598 int incr; /* 1 if does not fit, -1 if "easily" fits in a
1599 smaller bucket, otherwise 0. */
1600 char *cp = (char*)mp;
1602 #if defined(DEBUGGING) || !defined(PERL_CORE)
1603 MEM_SIZE size = nbytes;
1605 if ((long)nbytes < 0)
1606 croak("%s", "panic: realloc");
1609 BARK_64K_LIMIT("Reallocation",nbytes,size);
1611 return Perl_malloc(nbytes);
1613 ovp = (union overhead *)((caddr_t)cp
1614 - sizeof (union overhead) * CHUNK_SHIFT);
1615 bucket = OV_INDEX(ovp);
1617 #ifdef IGNORE_SMALL_BAD_FREE
1618 if ((bucket >= FIRST_BUCKET_WITH_CHECK)
1619 && (OV_MAGIC(ovp, bucket) != MAGIC))
1621 if (OV_MAGIC(ovp, bucket) != MAGIC)
1624 static int bad_free_warn = -1;
1625 if (bad_free_warn == -1) {
1627 char *pbf = PerlEnv_getenv("PERL_BADFREE");
1628 bad_free_warn = (pbf) ? atoi(pbf) : 1;
1636 if (!PERL_IS_ALIVE || !PL_curcop || ckWARN_d(WARN_MALLOC))
1637 Perl_warner(aTHX_ WARN_MALLOC, "%srealloc() %signored",
1638 (ovp->ov_rmagic == RMAGIC - 1 ? "" : "Bad "),
1639 ovp->ov_rmagic == RMAGIC - 1
1640 ? "of freed memory " : "");
1643 warn("%srealloc() %signored",
1644 (ovp->ov_rmagic == RMAGIC - 1 ? "" : "Bad "),
1645 ovp->ov_rmagic == RMAGIC - 1 ? "of freed memory " : "");
1651 if (!PERL_IS_ALIVE || !PL_curcop || ckWARN_d(WARN_MALLOC))
1652 Perl_warner(aTHX_ WARN_MALLOC, "%s",
1653 "Bad realloc() ignored");
1656 warn("%s", "Bad realloc() ignored");
1659 return Nullch; /* sanity */
1662 onb = BUCKET_SIZE_REAL(bucket);
1664 * avoid the copy if same size block.
1665 * We are not agressive with boundary cases. Note that it might
1666 * (for a small number of cases) give false negative if
1667 * both new size and old one are in the bucket for
1668 * FIRST_BIG_POW2, but the new one is near the lower end.
1670 * We do not try to go to 1.5 times smaller bucket so far.
1672 if (nbytes > onb) incr = 1;
1674 #ifdef DO_NOT_TRY_HARDER_WHEN_SHRINKING
1675 if ( /* This is a little bit pessimal if PACK_MALLOC: */
1676 nbytes > ( (onb >> 1) - M_OVERHEAD )
1677 # ifdef TWO_POT_OPTIMIZE
1678 || (bucket == FIRST_BIG_POW2 && nbytes >= LAST_SMALL_BOUND )
1681 #else /* !DO_NOT_TRY_HARDER_WHEN_SHRINKING */
1682 prev_bucket = ( (bucket > MAX_PACKED + 1)
1683 ? bucket - BUCKETS_PER_POW2
1685 if (nbytes > BUCKET_SIZE_REAL(prev_bucket))
1686 #endif /* !DO_NOT_TRY_HARDER_WHEN_SHRINKING */
1690 #ifdef STRESS_REALLOC
1697 * Record new allocated size of block and
1698 * bound space with magic numbers.
1700 if (OV_INDEX(ovp) <= MAX_SHORT_BUCKET) {
1701 int i, nb = ovp->ov_size + 1;
1706 ASSERT(*((char *)((caddr_t)ovp + nb - RSLOP + i)) == RMAGIC_C, "chunk's tail overwrite");
1710 ASSERT(*(u_int *)((caddr_t)ovp + nb - RSLOP) == RMAGIC, "chunk's tail overwrite");
1712 * Convert amount of memory requested into
1713 * closest block size stored in hash buckets
1714 * which satisfies request. Account for
1715 * space used per block for accounting.
1717 nbytes += M_OVERHEAD;
1718 ovp->ov_size = nbytes - 1;
1719 if ((i = nbytes & 3)) {
1722 *((char *)((caddr_t)ovp + nbytes - RSLOP + i))
1725 nbytes = (nbytes + 3) &~ 3;
1726 *((u_int *)((caddr_t)ovp + nbytes - RSLOP)) = RMAGIC;
1730 DEBUG_m(PerlIO_printf(Perl_debug_log,
1731 "0x%"UVxf": (%05lu) realloc %ld bytes inplace\n",
1732 PTR2UV(res),(unsigned long)(PL_an++),
1734 } else if (incr == 1 && (cp - M_OVERHEAD == last_op)
1735 && (onb > (1 << LOG_OF_MIN_ARENA))) {
1736 MEM_SIZE require, newarena = nbytes, pow;
1739 POW2_OPTIMIZE_ADJUST(newarena);
1740 newarena = newarena + M_OVERHEAD;
1741 /* newarena = (newarena + 3) &~ 3; */
1742 shiftr = (newarena - 1) >> LOG_OF_MIN_ARENA;
1743 pow = LOG_OF_MIN_ARENA + 1;
1744 /* apart from this loop, this is O(1) */
1745 while (shiftr >>= 1)
1747 newarena = (1 << pow) + POW2_OPTIMIZE_SURPLUS(pow * BUCKETS_PER_POW2);
1748 require = newarena - onb - M_OVERHEAD;
1751 if (cp - M_OVERHEAD == last_op /* We *still* are the last chunk */
1752 && getpages_adjacent(require)) {
1753 #ifdef DEBUGGING_MSTATS
1755 nmalloc[pow * BUCKETS_PER_POW2]++;
1757 *(cp - M_OVERHEAD) = pow * BUCKETS_PER_POW2; /* Fill index. */
1766 DEBUG_m(PerlIO_printf(Perl_debug_log,
1767 "0x%"UVxf": (%05lu) realloc %ld bytes the hard way\n",
1768 PTR2UV(cp),(unsigned long)(PL_an++),
1770 if ((res = (char*)Perl_malloc(nbytes)) == NULL)
1772 if (cp != res) /* common optimization */
1773 Copy(cp, res, (MEM_SIZE)(nbytes<onb?nbytes:onb), char);
1776 return ((Malloc_t)res);
1780 Perl_calloc(register size_t elements, register size_t size)
1782 long sz = elements * size;
1783 Malloc_t p = Perl_malloc(sz);
1786 memset((void*)p, 0, sz);
1792 Perl_strdup(const char *s)
1794 MEM_SIZE l = strlen(s);
1795 char *s1 = (char *)Perl_malloc(l+1);
1797 Copy(s, s1, (MEM_SIZE)(l+1), char);
1803 Perl_putenv(char *a)
1805 /* Sometimes system's putenv conflicts with my_setenv() - this is system
1806 malloc vs Perl's free(). */
1813 while (*val && *val != '=')
1818 if (l < sizeof(buf))
1821 var = Perl_malloc(l + 1);
1822 Copy(a, var, l, char);
1824 my_setenv(var, val+1);
1832 Perl_malloced_size(void *p)
1834 union overhead *ovp = (union overhead *)
1835 ((caddr_t)p - sizeof (union overhead) * CHUNK_SHIFT);
1836 int bucket = OV_INDEX(ovp);
1838 /* The caller wants to have a complete control over the chunk,
1839 disable the memory checking inside the chunk. */
1840 if (bucket <= MAX_SHORT_BUCKET) {
1841 MEM_SIZE size = BUCKET_SIZE_REAL(bucket);
1842 ovp->ov_size = size + M_OVERHEAD - 1;
1843 *((u_int *)((caddr_t)ovp + size + M_OVERHEAD - RSLOP)) = RMAGIC;
1846 return BUCKET_SIZE_REAL(bucket);
1849 # ifdef BUCKETS_ROOT2
1850 # define MIN_EVEN_REPORT 6
1852 # define MIN_EVEN_REPORT MIN_BUCKET
1856 Perl_get_mstats(pTHX_ perl_mstats_t *buf, int buflen, int level)
1858 #ifdef DEBUGGING_MSTATS
1860 register union overhead *p;
1861 struct chunk_chain_s* nextchain;
1863 buf->topbucket = buf->topbucket_ev = buf->topbucket_odd
1864 = buf->totfree = buf->total = buf->total_chain = 0;
1866 buf->minbucket = MIN_BUCKET;
1868 for (i = MIN_BUCKET ; i < NBUCKETS; i++) {
1869 for (j = 0, p = nextf[i]; p; p = p->ov_next, j++)
1873 buf->ntotal[i] = nmalloc[i];
1875 buf->totfree += j * BUCKET_SIZE_REAL(i);
1876 buf->total += nmalloc[i] * BUCKET_SIZE_REAL(i);
1878 i % 2 ? (buf->topbucket_odd = i) : (buf->topbucket_ev = i);
1882 nextchain = chunk_chain;
1884 buf->total_chain += nextchain->size;
1885 nextchain = nextchain->next;
1887 buf->total_sbrk = goodsbrk + sbrk_slack;
1889 buf->sbrk_good = sbrk_good;
1890 buf->sbrk_slack = sbrk_slack;
1891 buf->start_slack = start_slack;
1892 buf->sbrked_remains = sbrked_remains;
1895 for (i = MIN_BUCKET ; i < NBUCKETS; i++) {
1898 buf->bucket_mem_size[i] = BUCKET_SIZE(i);
1899 buf->bucket_available_size[i] = BUCKET_SIZE_REAL(i);
1902 #endif /* defined DEBUGGING_MSTATS */
1903 return 0; /* XXX unused */
1906 * mstats - print out statistics about malloc
1908 * Prints two lines of numbers, one showing the length of the free list
1909 * for each size category, the second showing the number of mallocs -
1910 * frees for each size category.
1913 Perl_dump_mstats(pTHX_ char *s)
1915 #ifdef DEBUGGING_MSTATS
1917 register union overhead *p;
1918 perl_mstats_t buffer;
1919 unsigned long nf[NBUCKETS];
1920 unsigned long nt[NBUCKETS];
1921 struct chunk_chain_s* nextchain;
1925 get_mstats(&buffer, NBUCKETS, 0);
1928 PerlIO_printf(Perl_error_log,
1929 "Memory allocation statistics %s (buckets %ld(%ld)..%ld(%ld)\n",
1931 (long)BUCKET_SIZE_REAL(MIN_BUCKET),
1932 (long)BUCKET_SIZE(MIN_BUCKET),
1933 (long)BUCKET_SIZE_REAL(buffer.topbucket),
1934 (long)BUCKET_SIZE(buffer.topbucket));
1935 PerlIO_printf(Perl_error_log, "%8ld free:", buffer.totfree);
1936 for (i = MIN_EVEN_REPORT; i <= buffer.topbucket; i += BUCKETS_PER_POW2) {
1937 PerlIO_printf(Perl_error_log,
1938 ((i < 8*BUCKETS_PER_POW2 || i == 10*BUCKETS_PER_POW2)
1940 : ((i < 12*BUCKETS_PER_POW2) ? " %3d" : " %d")),
1943 #ifdef BUCKETS_ROOT2
1944 PerlIO_printf(Perl_error_log, "\n\t ");
1945 for (i = MIN_BUCKET + 1; i <= buffer.topbucket_odd; i += BUCKETS_PER_POW2) {
1946 PerlIO_printf(Perl_error_log,
1947 ((i < 8*BUCKETS_PER_POW2 || i == 10*BUCKETS_PER_POW2)
1949 : ((i < 12*BUCKETS_PER_POW2) ? " %3d" : " %d")),
1953 PerlIO_printf(Perl_error_log, "\n%8ld used:", buffer.total - buffer.totfree);
1954 for (i = MIN_EVEN_REPORT; i <= buffer.topbucket; i += BUCKETS_PER_POW2) {
1955 PerlIO_printf(Perl_error_log,
1956 ((i < 8*BUCKETS_PER_POW2 || i == 10*BUCKETS_PER_POW2)
1958 : ((i < 12*BUCKETS_PER_POW2) ? " %3d" : " %d")),
1959 buffer.ntotal[i] - buffer.nfree[i]);
1961 #ifdef BUCKETS_ROOT2
1962 PerlIO_printf(Perl_error_log, "\n\t ");
1963 for (i = MIN_BUCKET + 1; i <= buffer.topbucket_odd; i += BUCKETS_PER_POW2) {
1964 PerlIO_printf(Perl_error_log,
1965 ((i < 8*BUCKETS_PER_POW2 || i == 10*BUCKETS_PER_POW2)
1967 : ((i < 12*BUCKETS_PER_POW2) ? " %3d" : " %d")),
1968 buffer.ntotal[i] - buffer.nfree[i]);
1971 PerlIO_printf(Perl_error_log, "\nTotal sbrk(): %ld/%ld:%ld. Odd ends: pad+heads+chain+tail: %ld+%ld+%ld+%ld.\n",
1972 buffer.total_sbrk, buffer.sbrks, buffer.sbrk_good,
1973 buffer.sbrk_slack, buffer.start_slack,
1974 buffer.total_chain, buffer.sbrked_remains);
1975 #endif /* DEBUGGING_MSTATS */
1979 #ifdef USE_PERL_SBRK
1981 # if defined(__MACHTEN_PPC__) || defined(NeXT) || defined(__NeXT__) || defined(PURIFY)
1982 # define PERL_SBRK_VIA_MALLOC
1984 * MachTen's malloc() returns a buffer aligned on a two-byte boundary.
1985 * While this is adequate, it may slow down access to longer data
1986 * types by forcing multiple memory accesses. It also causes
1987 * complaints when RCHECK is in force. So we allocate six bytes
1988 * more than we need to, and return an address rounded up to an
1989 * eight-byte boundary.
1991 * 980701 Dominic Dunlop <domo@computer.org>
1993 # define SYSTEM_ALLOC_ALIGNMENT 2
1996 # ifdef PERL_SBRK_VIA_MALLOC
1998 /* it may seem schizophrenic to use perl's malloc and let it call system */
1999 /* malloc, the reason for that is only the 3.2 version of the OS that had */
2000 /* frequent core dumps within nxzonefreenolock. This sbrk routine put an */
2001 /* end to the cores */
2003 # ifndef SYSTEM_ALLOC
2004 # define SYSTEM_ALLOC(a) malloc(a)
2006 # ifndef SYSTEM_ALLOC_ALIGNMENT
2007 # define SYSTEM_ALLOC_ALIGNMENT MEM_ALIGNBYTES
2010 # endif /* PERL_SBRK_VIA_MALLOC */
2012 static IV Perl_sbrk_oldchunk;
2013 static long Perl_sbrk_oldsize;
2015 # define PERLSBRK_32_K (1<<15)
2016 # define PERLSBRK_64_K (1<<16)
2024 if (!size) return 0;
2026 reqsize = size; /* just for the DEBUG_m statement */
2029 size = (size + 0x7ff) & ~0x7ff;
2031 if (size <= Perl_sbrk_oldsize) {
2032 got = Perl_sbrk_oldchunk;
2033 Perl_sbrk_oldchunk += size;
2034 Perl_sbrk_oldsize -= size;
2036 if (size >= PERLSBRK_32_K) {
2039 size = PERLSBRK_64_K;
2042 # if NEEDED_ALIGNMENT > SYSTEM_ALLOC_ALIGNMENT
2043 size += NEEDED_ALIGNMENT - SYSTEM_ALLOC_ALIGNMENT;
2045 got = (IV)SYSTEM_ALLOC(size);
2046 # if NEEDED_ALIGNMENT > SYSTEM_ALLOC_ALIGNMENT
2047 got = (got + NEEDED_ALIGNMENT - 1) & ~(NEEDED_ALIGNMENT - 1);
2050 /* Chunk is small, register the rest for future allocs. */
2051 Perl_sbrk_oldchunk = got + reqsize;
2052 Perl_sbrk_oldsize = size - reqsize;
2056 DEBUG_m(PerlIO_printf(Perl_debug_log, "sbrk malloc size %ld (reqsize %ld), left size %ld, give addr 0x%"UVxf"\n",
2057 size, reqsize, Perl_sbrk_oldsize, PTR2UV(got)));
2062 #endif /* ! defined USE_PERL_SBRK */