5 #if defined(PERL_CORE) && !defined(DEBUGGING_MSTATS)
6 # define DEBUGGING_MSTATS
10 # if defined(DEBUGGING) && !defined(NO_RCHECK)
14 * malloc.c (Caltech) 2/21/82
15 * Chris Kingsley, kingsley@cit-20.
17 * This is a very fast storage allocator. It allocates blocks of a small
18 * number of different sizes, and keeps free lists of each size. Blocks that
19 * don't exactly fit are passed up to the next larger size. In this
20 * implementation, the available sizes are 2^n-4 (or 2^n-12) bytes long.
21 * If PACK_MALLOC is defined, small blocks are 2^n bytes long.
22 * This is designed for use in a program that uses vast quantities of memory,
23 * but bombs when it runs out.
31 #define DEBUG_m(a) if (debug & 128) a
34 /* I don't much care whether these are defined in sys/types.h--LAW */
36 #define u_char unsigned char
37 #define u_int unsigned int
38 #define u_short unsigned short
40 /* 286 and atarist like big chunks, which gives too much overhead. */
41 #if (defined(RCHECK) || defined(I286) || defined(atarist)) && defined(PACK_MALLOC)
47 * The description below is applicable if PACK_MALLOC is not defined.
49 * The overhead on a block is at least 4 bytes. When free, this space
50 * contains a pointer to the next free block, and the bottom two bits must
51 * be zero. When in use, the first byte is set to MAGIC, and the second
52 * byte is the size index. The remaining bytes are for alignment.
53 * If range checking is enabled and the size of the block fits
54 * in two bytes, then the top two bytes hold the size of the requested block
55 * plus the range checking words, and the header word MINUS ONE.
58 union overhead *ov_next; /* when free */
59 #if MEM_ALIGNBYTES > 4
60 double strut; /* alignment problems */
63 u_char ovu_magic; /* magic number */
64 u_char ovu_index; /* bucket # */
66 u_short ovu_size; /* actual block size */
67 u_int ovu_rmagic; /* range magic number */
70 #define ov_magic ovu.ovu_magic
71 #define ov_index ovu.ovu_index
72 #define ov_size ovu.ovu_size
73 #define ov_rmagic ovu.ovu_rmagic
77 static void botch _((char *s));
79 static void morecore _((int bucket));
80 static int findbucket _((union overhead *freep, int srchlen));
82 #define MAGIC 0xff /* magic # on accounting info */
83 #define RMAGIC 0x55555555 /* magic # on range info */
85 # define RSLOP sizeof (u_int)
86 # ifdef TWO_POT_OPTIMIZE
87 # define MAX_SHORT_BUCKET 12
89 # define MAX_SHORT_BUCKET 13
97 * In this case it is assumed that if we do sbrk() in 2K units, we
98 * will get 2K aligned blocks. The bucket number of the given subblock is
99 * on the boundary of 2K block which contains the subblock.
100 * Several following bytes contain the magic numbers for the subblocks
103 * Sizes of chunks are powers of 2 for chunks in buckets <=
104 * MAX_PACKED, after this they are (2^n - sizeof(union overhead)) (to
105 * get alignment right).
107 * We suppose that starts of all the chunks in a 2K block are in
108 * different 2^n-byte-long chunks. If the top of the last chunk is
109 * aligned on a boundary of 2K block, this means that
110 * sizeof(union overhead)*"number of chunks" < 2^n, or
111 * sizeof(union overhead)*2K < 4^n, or n > 6 + log2(sizeof()/2)/2, if a
112 * chunk of size 2^n - overhead is used. Since this rules out n = 7
113 * for 8 byte alignment, we specialcase allocation of the first of 16
114 * 128-byte-long chunks.
116 * Note that with the above assumption we automatically have enough
117 * place for MAGIC at the start of 2K block. Note also that we
118 * overlay union overhead over the chunk, thus the start of the chunk
119 * is immediately overwritten after freeing.
121 # define MAX_PACKED 6
122 # define MAX_2_POT_ALGO ((1<<(MAX_PACKED + 1)) - M_OVERHEAD)
123 # define TWOK_MASK ((1<<11) - 1)
124 # define TWOK_MASKED(x) ((u_int)(x) & ~TWOK_MASK)
125 # define TWOK_SHIFT(x) ((u_int)(x) & TWOK_MASK)
126 # define OV_INDEXp(block) ((u_char*)(TWOK_MASKED(block)))
127 # define OV_INDEX(block) (*OV_INDEXp(block))
128 # define OV_MAGIC(block,bucket) (*(OV_INDEXp(block) + \
129 (TWOK_SHIFT(block)>>(bucket + 3)) + \
130 (bucket > MAX_NONSHIFT ? 1 : 0)))
131 # define CHUNK_SHIFT 0
133 static u_char n_blks[11 - 3] = {224, 120, 62, 31, 16, 8, 4, 2};
134 static u_short blk_shift[11 - 3] = {256, 128, 64, 32,
135 16*sizeof(union overhead),
136 8*sizeof(union overhead),
137 4*sizeof(union overhead),
138 2*sizeof(union overhead),
139 # define MAX_NONSHIFT 2 /* Shift 64 greater than chunk 32. */
142 #else /* !PACK_MALLOC */
144 # define OV_MAGIC(block,bucket) (block)->ov_magic
145 # define OV_INDEX(block) (block)->ov_index
146 # define CHUNK_SHIFT 1
147 #endif /* !PACK_MALLOC */
149 # define M_OVERHEAD (sizeof(union overhead) + RSLOP)
152 * Big allocations are often of the size 2^n bytes. To make them a
153 * little bit better, make blocks of size 2^n+pagesize for big n.
156 #ifdef TWO_POT_OPTIMIZE
158 # ifndef PERL_PAGESIZE
159 # define PERL_PAGESIZE 4096
161 # ifndef FIRST_BIG_TWO_POT
162 # define FIRST_BIG_TWO_POT 14 /* 16K */
164 # define FIRST_BIG_BLOCK (1<<FIRST_BIG_TWO_POT) /* 16K */
165 /* If this value or more, check against bigger blocks. */
166 # define FIRST_BIG_BOUND (FIRST_BIG_BLOCK - M_OVERHEAD)
167 /* If less than this value, goes into 2^n-overhead-block. */
168 # define LAST_SMALL_BOUND ((FIRST_BIG_BLOCK>>1) - M_OVERHEAD)
170 #endif /* TWO_POT_OPTIMIZE */
172 #if defined(PERL_EMERGENCY_SBRK) && defined(PERL_CORE)
175 # define BIG_SIZE (1<<16) /* 64K */
178 static char *emergency_buffer;
179 static MEM_SIZE emergency_buffer_size;
185 if (size >= BIG_SIZE) {
186 /* Give the possibility to recover: */
187 die("Out of memory during request for %i bytes", size);
188 /* croak may eat too much memory. */
191 if (!emergency_buffer) {
192 /* First offense, give a possibility to recover by dieing. */
193 /* No malloc involved here: */
194 GV **gvp = (GV**)hv_fetch(defstash, "^M", 2, 0);
198 if (!gvp) gvp = (GV**)hv_fetch(defstash, "\015", 1, 0);
199 if (!gvp || !(sv = GvSV(*gvp)) || !SvPOK(sv)
200 || (SvLEN(sv) < (1<<11) - M_OVERHEAD))
201 return (char *)-1; /* Now die die die... */
203 /* Got it, now detach SvPV: */
205 /* Check alignment: */
206 if (((u_int)(pv - M_OVERHEAD)) & ((1<<11) - 1)) {
207 PerlIO_puts(PerlIO_stderr(),"Bad alignment of $^M!\n");
208 return (char *)-1; /* die die die */
211 emergency_buffer = pv - M_OVERHEAD;
212 emergency_buffer_size = SvLEN(sv) + M_OVERHEAD;
215 die("Out of memory!"); /* croak may eat too much memory. */
217 else if (emergency_buffer_size >= size) {
218 emergency_buffer_size -= size;
219 return emergency_buffer + emergency_buffer_size;
222 return (char *)-1; /* poor guy... */
225 #else /* !(defined(TWO_POT_OPTIMIZE) && defined(PERL_CORE)) */
226 # define emergency_sbrk(size) -1
227 #endif /* !(defined(TWO_POT_OPTIMIZE) && defined(PERL_CORE)) */
230 * nextf[i] is the pointer to the next free block of size 2^(i+3). The
231 * smallest allocatable block is 8 bytes. The overhead information
232 * precedes the data area returned to the user.
235 static union overhead *nextf[NBUCKETS];
238 #define sbrk(a) Perl_sbrk(a)
239 char * Perl_sbrk _((int size));
241 #ifdef DONT_DECLARE_STD
246 extern char *sbrk(int);
250 #ifdef DEBUGGING_MSTATS
252 * nmalloc[i] is the difference between the number of mallocs and frees
253 * for a given block size.
255 static u_int nmalloc[NBUCKETS];
256 static u_int goodsbrk;
257 static u_int sbrk_slack;
258 static u_int start_slack;
262 #define ASSERT(p) if (!(p)) botch(STRINGIFY(p)); else
266 PerlIO_printf(PerlIO_stderr(), "assertion botched: %s\n", s);
274 malloc(register size_t nbytes)
276 register union overhead *p;
277 register int bucket = 0;
278 register MEM_SIZE shiftr;
280 #if defined(DEBUGGING) || defined(RCHECK)
281 MEM_SIZE size = nbytes;
286 if (nbytes > 0xffff) {
287 PerlIO_printf(PerlIO_stderr(),
288 "Allocation too large: %lx\n", (long)nbytes);
291 #endif /* HAS_64K_LIMIT */
293 if ((long)nbytes < 0)
294 croak("panic: malloc");
296 #endif /* PERL_CORE */
298 MUTEX_LOCK(&malloc_mutex);
300 * Convert amount of memory requested into
301 * closest block size stored in hash buckets
302 * which satisfies request. Account for
303 * space used per block for accounting.
308 else if (nbytes > MAX_2_POT_ALGO)
311 #ifdef TWO_POT_OPTIMIZE
312 if (nbytes >= FIRST_BIG_BOUND)
313 nbytes -= PERL_PAGESIZE;
315 nbytes += M_OVERHEAD;
316 nbytes = (nbytes + 3) &~ 3;
318 shiftr = (nbytes - 1) >> 2;
319 /* apart from this loop, this is O(1) */
323 * If nothing in hash bucket right now,
324 * request more memory from the system.
326 if (nextf[bucket] == NULL)
328 if ((p = (union overhead *)nextf[bucket]) == NULL) {
329 MUTEX_UNLOCK(&malloc_mutex);
332 PerlIO_puts(PerlIO_stderr(),"Out of memory!\n");
341 DEBUG_m(PerlIO_printf(Perl_debug_log, "0x%lx: (%05lu) malloc %ld bytes\n",
342 (unsigned long)(p+1),(unsigned long)(an++),(long)size));
343 #endif /* PERL_CORE */
345 /* remove from linked list */
347 if (*((int*)p) & (sizeof(union overhead) - 1))
348 PerlIO_printf(PerlIO_stderr(), "Corrupt malloc ptr 0x%lx at 0x%lx\n",
349 (unsigned long)*((int*)p),(unsigned long)p);
351 nextf[bucket] = p->ov_next;
352 OV_MAGIC(p, bucket) = MAGIC;
354 OV_INDEX(p) = bucket;
358 * Record allocated size of block and
359 * bound space with magic numbers.
361 nbytes = (size + M_OVERHEAD + 3) &~ 3;
362 if (nbytes <= 0x10000)
363 p->ov_size = nbytes - 1;
364 p->ov_rmagic = RMAGIC;
365 *((u_int *)((caddr_t)p + nbytes - RSLOP)) = RMAGIC;
367 MUTEX_UNLOCK(&malloc_mutex);
368 return ((Malloc_t)(p + CHUNK_SHIFT));
372 * Allocate more memory to the indicated bucket.
375 morecore(register int bucket)
377 register union overhead *ovp;
378 register int rnu; /* 2^rnu bytes will be requested */
379 register int nblks; /* become nblks blocks of the desired size */
380 register MEM_SIZE siz, needed;
385 if (bucket == (sizeof(MEM_SIZE)*8 - 3)) {
386 croak("Allocation too large");
389 * Insure memory is allocated
390 * on a page boundary. Should
391 * make getpageize call?
393 #ifndef atarist /* on the atari we dont have to worry about this */
394 ovp = (union overhead *)sbrk(0);
396 if ((UV)ovp & (0x7FF >> CHUNK_SHIFT)) {
397 slack = (0x800 >> CHUNK_SHIFT) - ((UV)ovp & (0x7FF >> CHUNK_SHIFT));
399 # if defined(DEBUGGING_MSTATS)
404 /* The sbrk(0) call on the I286 always returns the next segment */
408 #if !(defined(I286) || defined(atarist))
409 /* take 2k unless the block is bigger than that */
410 rnu = (bucket <= 8) ? 11 : bucket + 3;
412 /* take 16k unless the block is bigger than that
413 (80286s like large segments!), probably good on the atari too */
414 rnu = (bucket <= 11) ? 14 : bucket + 3;
416 nblks = 1 << (rnu - (bucket + 3)); /* how many blocks to get */
417 needed = (MEM_SIZE)1 << rnu;
418 #ifdef TWO_POT_OPTIMIZE
419 needed += (bucket >= (FIRST_BIG_TWO_POT - 3) ? PERL_PAGESIZE : 0);
421 ovp = (union overhead *)sbrk(needed);
423 if (ovp == (union overhead *)-1) {
424 ovp = (union overhead *)emergency_sbrk(needed);
425 if (ovp == (union overhead *)-1)
428 #ifdef DEBUGGING_MSTATS
432 * Round up to minimum allocation size boundary
433 * and deduct from block count to reflect.
438 croak("panic: Off-page sbrk");
441 ovp = (union overhead *)(((UV)ovp + 8) & ~7);
445 /* Again, this should always be ok on an 80286 */
448 * Add new memory allocated to that on
449 * free list for this hash bucket.
451 siz = 1 << (bucket + 3);
453 *(u_char*)ovp = bucket; /* Fill index. */
454 if (bucket <= MAX_PACKED - 3) {
455 ovp = (union overhead *) ((char*)ovp + blk_shift[bucket]);
456 nblks = n_blks[bucket];
457 # ifdef DEBUGGING_MSTATS
458 start_slack += blk_shift[bucket];
460 } else if (bucket <= 11 - 1 - 3) {
461 ovp = (union overhead *) ((char*)ovp + blk_shift[bucket]);
462 /* nblks = n_blks[bucket]; */
463 siz -= sizeof(union overhead);
464 } else ovp++; /* One chunk per block. */
465 #endif /* !PACK_MALLOC */
467 #ifdef DEBUGGING_MSTATS
468 nmalloc[bucket] += nblks;
470 while (--nblks > 0) {
471 ovp->ov_next = (union overhead *)((caddr_t)ovp + siz);
472 ovp = (union overhead *)((caddr_t)ovp + siz);
474 /* Not all sbrks return zeroed memory.*/
475 ovp->ov_next = (union overhead *)NULL;
477 if (bucket == 7 - 3) { /* Special case, explanation is above. */
478 union overhead *n_op = nextf[7 - 3]->ov_next;
479 nextf[7 - 3] = (union overhead *)((caddr_t)nextf[7 - 3]
480 - sizeof(union overhead));
481 nextf[7 - 3]->ov_next = n_op;
483 #endif /* !PACK_MALLOC */
489 register MEM_SIZE size;
490 register union overhead *ovp;
491 char *cp = (char*)mp;
497 DEBUG_m(PerlIO_printf(Perl_debug_log, "0x%lx: (%05lu) free\n",(unsigned long)cp,(unsigned long)(an++)));
498 #endif /* PERL_CORE */
502 ovp = (union overhead *)((caddr_t)cp
503 - sizeof (union overhead) * CHUNK_SHIFT);
505 bucket = OV_INDEX(ovp);
507 if (OV_MAGIC(ovp, bucket) != MAGIC) {
508 static int bad_free_warn = -1;
509 if (bad_free_warn == -1) {
510 char *pbf = getenv("PERL_BADFREE");
511 bad_free_warn = (pbf) ? atoi(pbf) : 1;
516 warn("%s free() ignored",
517 ovp->ov_rmagic == RMAGIC - 1 ? "Duplicate" : "Bad");
519 warn("Bad free() ignored");
523 MUTEX_LOCK(&malloc_mutex);
525 ASSERT(ovp->ov_rmagic == RMAGIC);
526 if (OV_INDEX(ovp) <= MAX_SHORT_BUCKET)
527 ASSERT(*(u_int *)((caddr_t)ovp + ovp->ov_size + 1 - RSLOP) == RMAGIC);
528 ovp->ov_rmagic = RMAGIC - 1;
530 ASSERT(OV_INDEX(ovp) < NBUCKETS);
531 size = OV_INDEX(ovp);
532 ovp->ov_next = nextf[size];
534 MUTEX_UNLOCK(&malloc_mutex);
538 * When a program attempts "storage compaction" as mentioned in the
539 * old malloc man page, it realloc's an already freed block. Usually
540 * this is the last block it freed; occasionally it might be farther
541 * back. We have to search all the free lists for the block in order
542 * to determine its bucket: 1st we make one pass thru the lists
543 * checking only the first block in each; if that fails we search
544 * ``reall_srchlen'' blocks in each list for a match (the variable
545 * is extern so the caller can modify it). If that fails we just copy
546 * however many bytes was given to realloc() and hope it's not huge.
548 int reall_srchlen = 4; /* 4 should be plenty, -1 =>'s whole list */
551 realloc(void *mp, size_t nbytes)
553 register MEM_SIZE onb;
558 char *cp = (char*)mp;
561 MEM_SIZE size = nbytes;
566 if (nbytes > 0xffff) {
567 PerlIO_printf(PerlIO_stderr(),
568 "Reallocation too large: %lx\n", size);
571 #endif /* HAS_64K_LIMIT */
573 return malloc(nbytes);
575 if ((long)nbytes < 0)
576 croak("panic: realloc");
578 #endif /* PERL_CORE */
580 MUTEX_LOCK(&malloc_mutex);
581 ovp = (union overhead *)((caddr_t)cp
582 - sizeof (union overhead) * CHUNK_SHIFT);
584 if (OV_MAGIC(ovp, i) == MAGIC) {
588 * Already free, doing "compaction".
590 * Search for the old block of memory on the
591 * free list. First, check the most common
592 * case (last element free'd), then (this failing)
593 * the last ``reall_srchlen'' items free'd.
594 * If all lookups fail, then assume the size of
595 * the memory block being realloc'd is the
598 if ((i = findbucket(ovp, 1)) < 0 &&
599 (i = findbucket(ovp, reall_srchlen)) < 0)
602 onb = (1L << (i + 3)) -
604 (i <= (MAX_PACKED - 3) ? 0 : M_OVERHEAD)
608 #ifdef TWO_POT_OPTIMIZE
609 + (i >= (FIRST_BIG_TWO_POT - 3) ? PERL_PAGESIZE : 0)
613 * avoid the copy if same size block.
614 * We are not agressive with boundary cases. Note that it is
615 * possible for small number of cases give false negative if
616 * both new size and old one are in the bucket for
617 * FIRST_BIG_TWO_POT, but the new one is near the lower end.
620 nbytes <= onb && (nbytes > ( (onb >> 1) - M_OVERHEAD )
621 #ifdef TWO_POT_OPTIMIZE
622 || (i == (FIRST_BIG_TWO_POT - 3)
623 && nbytes >= LAST_SMALL_BOUND )
628 * Record new allocated size of block and
629 * bound space with magic numbers.
631 if (OV_INDEX(ovp) <= MAX_SHORT_BUCKET) {
633 * Convert amount of memory requested into
634 * closest block size stored in hash buckets
635 * which satisfies request. Account for
636 * space used per block for accounting.
638 nbytes += M_OVERHEAD;
639 nbytes = (nbytes + 3) &~ 3;
640 ovp->ov_size = nbytes - 1;
641 *((u_int *)((caddr_t)ovp + nbytes - RSLOP)) = RMAGIC;
645 MUTEX_UNLOCK(&malloc_mutex);
648 MUTEX_UNLOCK(&malloc_mutex);
649 if ((res = (char*)malloc(nbytes)) == NULL)
651 if (cp != res) /* common optimization */
652 Copy(cp, res, (MEM_SIZE)(nbytes<onb?nbytes:onb), char);
660 PerlIO_printf(Perl_debug_log, "0x%lx: (%05lu) rfree\n",(unsigned long)res,(unsigned long)(an++));
661 PerlIO_printf(Perl_debug_log, "0x%lx: (%05lu) realloc %ld bytes\n",
662 (unsigned long)res,(unsigned long)(an++),(long)size);
665 #endif /* PERL_CORE */
666 return ((Malloc_t)res);
670 * Search ``srchlen'' elements of each free list for a block whose
671 * header starts at ``freep''. If srchlen is -1 search the whole list.
672 * Return bucket number, or -1 if not found.
675 findbucket(union overhead *freep, int srchlen)
677 register union overhead *p;
680 for (i = 0; i < NBUCKETS; i++) {
682 for (p = nextf[i]; p && j != srchlen; p = p->ov_next) {
692 calloc(register size_t elements, register size_t size)
694 long sz = elements * size;
695 Malloc_t p = malloc(sz);
698 memset((void*)p, 0, sz);
703 #ifdef DEBUGGING_MSTATS
705 * mstats - print out statistics about malloc
707 * Prints two lines of numbers, one showing the length of the free list
708 * for each size category, the second showing the number of mallocs -
709 * frees for each size category.
715 register union overhead *p;
716 int topbucket=0, totfree=0, total=0;
717 u_int nfree[NBUCKETS];
719 for (i=0; i < NBUCKETS; i++) {
720 for (j = 0, p = nextf[i]; p; p = p->ov_next, j++)
723 totfree += nfree[i] * (1 << (i + 3));
724 total += nmalloc[i] * (1 << (i + 3));
729 PerlIO_printf(PerlIO_stderr(), "Memory allocation statistics %s (buckets 8..%d)\n",
730 s, (1 << (topbucket + 3)) );
731 PerlIO_printf(PerlIO_stderr(), "%8d free:", totfree);
732 for (i=0; i <= topbucket; i++) {
733 PerlIO_printf(PerlIO_stderr(), (i<5 || i==7)?" %5d": (i<9)?" %3d":" %d", nfree[i]);
735 PerlIO_printf(PerlIO_stderr(), "\n%8d used:", total - totfree);
736 for (i=0; i <= topbucket; i++) {
737 PerlIO_printf(PerlIO_stderr(), (i<5 || i==7)?" %5d": (i<9)?" %3d":" %d", nmalloc[i] - nfree[i]);
739 PerlIO_printf(PerlIO_stderr(), "\nTotal sbrk(): %8d. Odd ends: sbrk(): %7d, malloc(): %7d bytes.\n",
740 goodsbrk + sbrk_slack, sbrk_slack, start_slack);
754 # define PERL_SBRK_VIA_MALLOC
757 # ifdef PERL_SBRK_VIA_MALLOC
758 # if defined(HIDEMYMALLOC) || defined(EMBEDMYMALLOC)
761 # include "Error: -DPERL_SBRK_VIA_MALLOC needs -D(HIDE|EMBED)MYMALLOC"
764 /* it may seem schizophrenic to use perl's malloc and let it call system */
765 /* malloc, the reason for that is only the 3.2 version of the OS that had */
766 /* frequent core dumps within nxzonefreenolock. This sbrk routine put an */
767 /* end to the cores */
769 # define SYSTEM_ALLOC(a) malloc(a)
771 # endif /* PERL_SBRK_VIA_MALLOC */
773 static IV Perl_sbrk_oldchunk;
774 static long Perl_sbrk_oldsize;
776 # define PERLSBRK_32_K (1<<15)
777 # define PERLSBRK_64_K (1<<16)
788 reqsize = size; /* just for the DEBUG_m statement */
791 size = (size + 0x7ff) & ~0x7ff;
793 if (size <= Perl_sbrk_oldsize) {
794 got = Perl_sbrk_oldchunk;
795 Perl_sbrk_oldchunk += size;
796 Perl_sbrk_oldsize -= size;
798 if (size >= PERLSBRK_32_K) {
804 size = PERLSBRK_64_K;
807 got = (IV)SYSTEM_ALLOC(size);
809 got = (got + 0x7ff) & ~0x7ff;
812 /* Chunk is small, register the rest for future allocs. */
813 Perl_sbrk_oldchunk = got + reqsize;
814 Perl_sbrk_oldsize = size - reqsize;
819 DEBUG_m(PerlIO_printf(Perl_debug_log, "sbrk malloc size %ld (reqsize %ld), left size %ld, give addr 0x%lx\n",
820 size, reqsize, Perl_sbrk_oldsize, got));
826 #endif /* ! defined USE_PERL_SBRK */