forked from schacon/perl
/
malloc.c
1637 lines (1479 loc) · 46.5 KB
/
malloc.c
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
/* malloc.c
*
*/
/*
Here are some notes on configuring Perl's malloc.
There are two macros which serve as bulk disablers of advanced
features of this malloc: NO_FANCY_MALLOC, PLAIN_MALLOC (undef by
default). Look in the list of default values below to understand
their exact effect. Defining NO_FANCY_MALLOC returns malloc.c to the
state of the malloc in Perl 5.004. Additionally defining PLAIN_MALLOC
returns it to the state as of Perl 5.000.
Note that some of the settings below may be ignored in the code based
on values of other macros. The PERL_CORE symbol is only defined when
perl itself is being compiled (so malloc can make some assumptions
about perl's facilities being available to it).
Each config option has a short description, followed by its name,
default value, and a comment about the default (if applicable). Some
options take a precise value, while the others are just boolean.
The boolean ones are listed first.
# Enable code for an emergency memory pool in $^M. See perlvar.pod
# for a description of $^M.
PERL_EMERGENCY_SBRK (!PLAIN_MALLOC && PERL_CORE)
# Enable code for printing memory statistics.
DEBUGGING_MSTATS (!PLAIN_MALLOC && PERL_CORE)
# Move allocation info for small buckets into separate areas.
# Memory optimization (especially for small allocations, of the
# less than 64 bytes). Since perl usually makes a large number
# of small allocations, this is usually a win.
PACK_MALLOC (!PLAIN_MALLOC && !RCHECK)
# Add one page to big powers of two when calculating bucket size.
# This is targeted at big allocations, as are common in image
# processing.
TWO_POT_OPTIMIZE !PLAIN_MALLOC
# Use intermediate bucket sizes between powers-of-two. This is
# generally a memory optimization, and a (small) speed pessimization.
BUCKETS_ROOT2 !NO_FANCY_MALLOC
# Do not check small deallocations for bad free(). Memory
# and speed optimization, error reporting pessimization.
IGNORE_SMALL_BAD_FREE (!NO_FANCY_MALLOC && !RCHECK)
# Use table lookup to decide in which bucket a given allocation will go.
SMALL_BUCKET_VIA_TABLE !NO_FANCY_MALLOC
# Use a perl-defined sbrk() instead of the (presumably broken or
# missing) system-supplied sbrk().
USE_PERL_SBRK undef
# Use system malloc() (or calloc() etc.) to emulate sbrk(). Normally
# only used with broken sbrk()s.
PERL_SBRK_VIA_MALLOC undef
# Which allocator to use if PERL_SBRK_VIA_MALLOC
SYSTEM_ALLOC(a) malloc(a)
# Disable memory overwrite checking with DEBUGGING. Memory and speed
# optimization, error reporting pessimization.
NO_RCHECK undef
# Enable memory overwrite checking with DEBUGGING. Memory and speed
# pessimization, error reporting optimization
RCHECK (DEBUGGING && !NO_RCHECK)
# Failed allocations bigger than this size croak (if
# PERL_EMERGENCY_SBRK is enabled) without touching $^M. See
# perlvar.pod for a description of $^M.
BIG_SIZE (1<<16) # 64K
# Starting from this power of two, add an extra page to the
# size of the bucket. This enables optimized allocations of sizes
# close to powers of 2. Note that the value is indexed at 0.
FIRST_BIG_POW2 15 # 32K, 16K is used too often
# Estimate of minimal memory footprint. malloc uses this value to
# request the most reasonable largest blocks of memory from the system.
FIRST_SBRK (48*1024)
# Round up sbrk()s to multiples of this.
MIN_SBRK 2048
# Round up sbrk()s to multiples of this percent of footprint.
MIN_SBRK_FRAC 3
# Add this much memory to big powers of two to get the bucket size.
PERL_PAGESIZE 4096
# This many sbrk() discontinuities should be tolerated even
# from the start without deciding that sbrk() is usually
# discontinuous.
SBRK_ALLOW_FAILURES 3
# This many continuous sbrk()s compensate for one discontinuous one.
SBRK_FAILURE_PRICE 50
This implementation assumes that calling PerlIO_printf() does not
result in any memory allocation calls (used during a panic).
*/
#ifndef NO_FANCY_MALLOC
# ifndef SMALL_BUCKET_VIA_TABLE
# define SMALL_BUCKET_VIA_TABLE
# endif
# ifndef BUCKETS_ROOT2
# define BUCKETS_ROOT2
# endif
# ifndef IGNORE_SMALL_BAD_FREE
# define IGNORE_SMALL_BAD_FREE
# endif
#endif
#ifndef PLAIN_MALLOC /* Bulk enable features */
# ifndef PACK_MALLOC
# define PACK_MALLOC
# endif
# ifndef TWO_POT_OPTIMIZE
# define TWO_POT_OPTIMIZE
# endif
# if defined(PERL_CORE) && !defined(PERL_EMERGENCY_SBRK)
# define PERL_EMERGENCY_SBRK
# endif
# if defined(PERL_CORE) && !defined(DEBUGGING_MSTATS)
# define DEBUGGING_MSTATS
# endif
#endif
#define MIN_BUC_POW2 (sizeof(void*) > 4 ? 3 : 2) /* Allow for 4-byte arena. */
#define MIN_BUCKET (MIN_BUC_POW2 * BUCKETS_PER_POW2)
#if !(defined(I286) || defined(atarist))
/* take 2k unless the block is bigger than that */
# define LOG_OF_MIN_ARENA 11
#else
/* take 16k unless the block is bigger than that
(80286s like large segments!), probably good on the atari too */
# define LOG_OF_MIN_ARENA 14
#endif
#ifndef lint
# if defined(DEBUGGING) && !defined(NO_RCHECK)
# define RCHECK
# endif
# if defined(RCHECK) && defined(IGNORE_SMALL_BAD_FREE)
# undef IGNORE_SMALL_BAD_FREE
# endif
/*
* malloc.c (Caltech) 2/21/82
* Chris Kingsley, kingsley@cit-20.
*
* This is a very fast storage allocator. It allocates blocks of a small
* number of different sizes, and keeps free lists of each size. Blocks that
* don't exactly fit are passed up to the next larger size. In this
* implementation, the available sizes are 2^n-4 (or 2^n-12) bytes long.
* If PACK_MALLOC is defined, small blocks are 2^n bytes long.
* This is designed for use in a program that uses vast quantities of memory,
* but bombs when it runs out.
*/
#ifdef PERL_CORE
# include "EXTERN.h"
# include "perl.h"
#else
# ifdef PERL_FOR_X2P
# include "../EXTERN.h"
# include "../perl.h"
# else
# include <stdlib.h>
# include <stdio.h>
# include <memory.h>
# define _(arg) arg
# ifndef Malloc_t
# define Malloc_t void *
# endif
# ifndef MEM_SIZE
# define MEM_SIZE unsigned long
# endif
# ifndef LONG_MAX
# define LONG_MAX 0x7FFFFFFF
# endif
# ifndef UV
# define UV unsigned long
# endif
# ifndef caddr_t
# define caddr_t char *
# endif
# ifndef Free_t
# define Free_t void
# endif
# define Copy(s,d,n,t) (void)memcpy((char*)(d),(char*)(s), (n) * sizeof(t))
# define PerlEnv_getenv getenv
# define PerlIO_printf fprintf
# define PerlIO_stderr() stderr
# endif
# ifndef croak /* make depend */
# define croak(mess, arg) warn((mess), (arg)); exit(1);
# endif
# ifndef warn
# define warn(mess, arg) fprintf(stderr, (mess), (arg));
# endif
# ifdef DEBUG_m
# undef DEBUG_m
# endif
# define DEBUG_m(a)
# ifdef DEBUGGING
# undef DEBUGGING
# endif
#endif
#ifndef MUTEX_LOCK
# define MUTEX_LOCK(l)
#endif
#ifndef MUTEX_UNLOCK
# define MUTEX_UNLOCK(l)
#endif
#ifdef DEBUGGING
# undef DEBUG_m
# define DEBUG_m(a) if (PL_debug & 128) a
#endif
/* I don't much care whether these are defined in sys/types.h--LAW */
#define u_char unsigned char
#define u_int unsigned int
#ifdef HAS_QUAD
# define u_bigint UV /* Needs to eat *void. */
#else /* needed? */
# define u_bigint unsigned long /* Needs to eat *void. */
#endif
#define u_short unsigned short
/* 286 and atarist like big chunks, which gives too much overhead. */
#if (defined(RCHECK) || defined(I286) || defined(atarist)) && defined(PACK_MALLOC)
# undef PACK_MALLOC
#endif
/*
* The description below is applicable if PACK_MALLOC is not defined.
*
* The overhead on a block is at least 4 bytes. When free, this space
* contains a pointer to the next free block, and the bottom two bits must
* be zero. When in use, the first byte is set to MAGIC, and the second
* byte is the size index. The remaining bytes are for alignment.
* If range checking is enabled and the size of the block fits
* in two bytes, then the top two bytes hold the size of the requested block
* plus the range checking words, and the header word MINUS ONE.
*/
union overhead {
union overhead *ov_next; /* when free */
#if MEM_ALIGNBYTES > 4
double strut; /* alignment problems */
#endif
struct {
u_char ovu_magic; /* magic number */
u_char ovu_index; /* bucket # */
#ifdef RCHECK
u_short ovu_size; /* actual block size */
u_int ovu_rmagic; /* range magic number */
#endif
} ovu;
#define ov_magic ovu.ovu_magic
#define ov_index ovu.ovu_index
#define ov_size ovu.ovu_size
#define ov_rmagic ovu.ovu_rmagic
};
#ifdef DEBUGGING
static void botch _((char *diag, char *s));
#endif
static void morecore _((int bucket));
static int findbucket _((union overhead *freep, int srchlen));
#define MAGIC 0xff /* magic # on accounting info */
#define RMAGIC 0x55555555 /* magic # on range info */
#define RMAGIC_C 0x55 /* magic # on range info */
#ifdef RCHECK
# define RSLOP sizeof (u_int)
# ifdef TWO_POT_OPTIMIZE
# define MAX_SHORT_BUCKET (12 * BUCKETS_PER_POW2)
# else
# define MAX_SHORT_BUCKET (13 * BUCKETS_PER_POW2)
# endif
#else
# define RSLOP 0
#endif
#if !defined(PACK_MALLOC) && defined(BUCKETS_ROOT2)
# undef BUCKETS_ROOT2
#endif
#ifdef BUCKETS_ROOT2
# define BUCKET_TABLE_SHIFT 2
# define BUCKET_POW2_SHIFT 1
# define BUCKETS_PER_POW2 2
#else
# define BUCKET_TABLE_SHIFT MIN_BUC_POW2
# define BUCKET_POW2_SHIFT 0
# define BUCKETS_PER_POW2 1
#endif
#if !defined(MEM_ALIGNBYTES) || ((MEM_ALIGNBYTES > 4) && !defined(STRICT_ALIGNMENT))
/* Figure out the alignment of void*. */
struct aligner {
char c;
void *p;
};
# define ALIGN_SMALL ((int)((caddr_t)&(((struct aligner*)0)->p)))
#else
# define ALIGN_SMALL MEM_ALIGNBYTES
#endif
#define IF_ALIGN_8(yes,no) ((ALIGN_SMALL>4) ? (yes) : (no))
#ifdef BUCKETS_ROOT2
# define MAX_BUCKET_BY_TABLE 13
static u_short buck_size[MAX_BUCKET_BY_TABLE + 1] =
{
0, 0, 0, 0, 4, 4, 8, 12, 16, 24, 32, 48, 64, 80,
};
# define BUCKET_SIZE(i) ((i) % 2 ? buck_size[i] : (1 << ((i) >> BUCKET_POW2_SHIFT)))
# define BUCKET_SIZE_REAL(i) ((i) <= MAX_BUCKET_BY_TABLE \
? buck_size[i] \
: ((1 << ((i) >> BUCKET_POW2_SHIFT)) \
- MEM_OVERHEAD(i) \
+ POW2_OPTIMIZE_SURPLUS(i)))
#else
# define BUCKET_SIZE(i) (1 << ((i) >> BUCKET_POW2_SHIFT))
# define BUCKET_SIZE_REAL(i) (BUCKET_SIZE(i) - MEM_OVERHEAD(i) + POW2_OPTIMIZE_SURPLUS(i))
#endif
#ifdef PACK_MALLOC
/* In this case it is assumed that if we do sbrk() in 2K units, we
* will get 2K aligned arenas (at least after some initial
* alignment). The bucket number of the given subblock is on the start
* of 2K arena which contains the subblock. Several following bytes
* contain the magic numbers for the subblocks in the block.
*
* Sizes of chunks are powers of 2 for chunks in buckets <=
* MAX_PACKED, after this they are (2^n - sizeof(union overhead)) (to
* get alignment right).
*
* Consider an arena for 2^n with n>MAX_PACKED. We suppose that
* starts of all the chunks in a 2K arena are in different
* 2^n-byte-long chunks. If the top of the last chunk is aligned on a
* boundary of 2K block, this means that sizeof(union
* overhead)*"number of chunks" < 2^n, or sizeof(union overhead)*2K <
* 4^n, or n > 6 + log2(sizeof()/2)/2, since a chunk of size 2^n -
* overhead is used. Since this rules out n = 7 for 8 byte alignment,
* we specialcase allocation of the first of 16 128-byte-long chunks.
*
* Note that with the above assumption we automatically have enough
* place for MAGIC at the start of 2K block. Note also that we
* overlay union overhead over the chunk, thus the start of small chunks
* is immediately overwritten after freeing. */
# define MAX_PACKED_POW2 6
# define MAX_PACKED (MAX_PACKED_POW2 * BUCKETS_PER_POW2 + BUCKET_POW2_SHIFT)
# define MAX_POW2_ALGO ((1<<(MAX_PACKED_POW2 + 1)) - M_OVERHEAD)
# define TWOK_MASK ((1<<LOG_OF_MIN_ARENA) - 1)
# define TWOK_MASKED(x) ((u_bigint)(x) & ~TWOK_MASK)
# define TWOK_SHIFT(x) ((u_bigint)(x) & TWOK_MASK)
# define OV_INDEXp(block) ((u_char*)(TWOK_MASKED(block)))
# define OV_INDEX(block) (*OV_INDEXp(block))
# define OV_MAGIC(block,bucket) (*(OV_INDEXp(block) + \
(TWOK_SHIFT(block)>> \
(bucket>>BUCKET_POW2_SHIFT)) + \
(bucket >= MIN_NEEDS_SHIFT ? 1 : 0)))
/* A bucket can have a shift smaller than it size, we need to
shift its magic number so it will not overwrite index: */
# ifdef BUCKETS_ROOT2
# define MIN_NEEDS_SHIFT (7*BUCKETS_PER_POW2 - 1) /* Shift 80 greater than chunk 64. */
# else
# define MIN_NEEDS_SHIFT (7*BUCKETS_PER_POW2) /* Shift 128 greater than chunk 32. */
# endif
# define CHUNK_SHIFT 0
/* Number of active buckets of given ordinal. */
#ifdef IGNORE_SMALL_BAD_FREE
#define FIRST_BUCKET_WITH_CHECK (6 * BUCKETS_PER_POW2) /* 64 */
# define N_BLKS(bucket) ( (bucket) < FIRST_BUCKET_WITH_CHECK \
? ((1<<LOG_OF_MIN_ARENA) - 1)/BUCKET_SIZE(bucket) \
: n_blks[bucket] )
#else
# define N_BLKS(bucket) n_blks[bucket]
#endif
static u_short n_blks[LOG_OF_MIN_ARENA * BUCKETS_PER_POW2] =
{
# if BUCKETS_PER_POW2==1
0, 0,
(MIN_BUC_POW2==2 ? 384 : 0),
224, 120, 62, 31, 16, 8, 4, 2
# else
0, 0, 0, 0,
(MIN_BUC_POW2==2 ? 384 : 0), (MIN_BUC_POW2==2 ? 384 : 0), /* 4, 4 */
224, 149, 120, 80, 62, 41, 31, 25, 16, 16, 8, 8, 4, 4, 2, 2
# endif
};
/* Shift of the first bucket with the given ordinal inside 2K chunk. */
#ifdef IGNORE_SMALL_BAD_FREE
# define BLK_SHIFT(bucket) ( (bucket) < FIRST_BUCKET_WITH_CHECK \
? ((1<<LOG_OF_MIN_ARENA) \
- BUCKET_SIZE(bucket) * N_BLKS(bucket)) \
: blk_shift[bucket])
#else
# define BLK_SHIFT(bucket) blk_shift[bucket]
#endif
static u_short blk_shift[LOG_OF_MIN_ARENA * BUCKETS_PER_POW2] =
{
# if BUCKETS_PER_POW2==1
0, 0,
(MIN_BUC_POW2==2 ? 512 : 0),
256, 128, 64, 64, /* 8 to 64 */
16*sizeof(union overhead),
8*sizeof(union overhead),
4*sizeof(union overhead),
2*sizeof(union overhead),
# else
0, 0, 0, 0,
(MIN_BUC_POW2==2 ? 512 : 0), (MIN_BUC_POW2==2 ? 512 : 0),
256, 260, 128, 128, 64, 80, 64, 48, /* 8 to 96 */
16*sizeof(union overhead), 16*sizeof(union overhead),
8*sizeof(union overhead), 8*sizeof(union overhead),
4*sizeof(union overhead), 4*sizeof(union overhead),
2*sizeof(union overhead), 2*sizeof(union overhead),
# endif
};
#else /* !PACK_MALLOC */
# define OV_MAGIC(block,bucket) (block)->ov_magic
# define OV_INDEX(block) (block)->ov_index
# define CHUNK_SHIFT 1
# define MAX_PACKED -1
#endif /* !PACK_MALLOC */
#define M_OVERHEAD (sizeof(union overhead) + RSLOP)
#ifdef PACK_MALLOC
# define MEM_OVERHEAD(bucket) \
(bucket <= MAX_PACKED ? 0 : M_OVERHEAD)
# ifdef SMALL_BUCKET_VIA_TABLE
# define START_SHIFTS_BUCKET ((MAX_PACKED_POW2 + 1) * BUCKETS_PER_POW2)
# define START_SHIFT MAX_PACKED_POW2
# ifdef BUCKETS_ROOT2 /* Chunks of size 3*2^n. */
# define SIZE_TABLE_MAX 80
# else
# define SIZE_TABLE_MAX 64
# endif
static char bucket_of[] =
{
# ifdef BUCKETS_ROOT2 /* Chunks of size 3*2^n. */
/* 0 to 15 in 4-byte increments. */
(sizeof(void*) > 4 ? 6 : 5), /* 4/8, 5-th bucket for better reports */
6, /* 8 */
IF_ALIGN_8(8,7), 8, /* 16/12, 16 */
9, 9, 10, 10, /* 24, 32 */
11, 11, 11, 11, /* 48 */
12, 12, 12, 12, /* 64 */
13, 13, 13, 13, /* 80 */
13, 13, 13, 13 /* 80 */
# else /* !BUCKETS_ROOT2 */
/* 0 to 15 in 4-byte increments. */
(sizeof(void*) > 4 ? 3 : 2),
3,
4, 4,
5, 5, 5, 5,
6, 6, 6, 6,
6, 6, 6, 6
# endif /* !BUCKETS_ROOT2 */
};
# else /* !SMALL_BUCKET_VIA_TABLE */
# define START_SHIFTS_BUCKET MIN_BUCKET
# define START_SHIFT (MIN_BUC_POW2 - 1)
# endif /* !SMALL_BUCKET_VIA_TABLE */
#else /* !PACK_MALLOC */
# define MEM_OVERHEAD(bucket) M_OVERHEAD
# ifdef SMALL_BUCKET_VIA_TABLE
# undef SMALL_BUCKET_VIA_TABLE
# endif
# define START_SHIFTS_BUCKET MIN_BUCKET
# define START_SHIFT (MIN_BUC_POW2 - 1)
#endif /* !PACK_MALLOC */
/*
* Big allocations are often of the size 2^n bytes. To make them a
* little bit better, make blocks of size 2^n+pagesize for big n.
*/
#ifdef TWO_POT_OPTIMIZE
# ifndef PERL_PAGESIZE
# define PERL_PAGESIZE 4096
# endif
# ifndef FIRST_BIG_POW2
# define FIRST_BIG_POW2 15 /* 32K, 16K is used too often. */
# endif
# define FIRST_BIG_BLOCK (1<<FIRST_BIG_POW2)
/* If this value or more, check against bigger blocks. */
# define FIRST_BIG_BOUND (FIRST_BIG_BLOCK - M_OVERHEAD)
/* If less than this value, goes into 2^n-overhead-block. */
# define LAST_SMALL_BOUND ((FIRST_BIG_BLOCK>>1) - M_OVERHEAD)
# define POW2_OPTIMIZE_ADJUST(nbytes) \
((nbytes >= FIRST_BIG_BOUND) ? nbytes -= PERL_PAGESIZE : 0)
# define POW2_OPTIMIZE_SURPLUS(bucket) \
((bucket >= FIRST_BIG_POW2 * BUCKETS_PER_POW2) ? PERL_PAGESIZE : 0)
#else /* !TWO_POT_OPTIMIZE */
# define POW2_OPTIMIZE_ADJUST(nbytes)
# define POW2_OPTIMIZE_SURPLUS(bucket) 0
#endif /* !TWO_POT_OPTIMIZE */
#if defined(HAS_64K_LIMIT) && defined(PERL_CORE)
# define BARK_64K_LIMIT(what,nbytes,size) \
if (nbytes > 0xffff) { \
PerlIO_printf(PerlIO_stderr(), \
"%s too large: %lx\n", what, size); \
my_exit(1); \
}
#else /* !HAS_64K_LIMIT || !PERL_CORE */
# define BARK_64K_LIMIT(what,nbytes,size)
#endif /* !HAS_64K_LIMIT || !PERL_CORE */
#ifndef MIN_SBRK
# define MIN_SBRK 2048
#endif
#ifndef FIRST_SBRK
# define FIRST_SBRK (48*1024)
#endif
/* Minimal sbrk in percents of what is already alloced. */
#ifndef MIN_SBRK_FRAC
# define MIN_SBRK_FRAC 3
#endif
#ifndef SBRK_ALLOW_FAILURES
# define SBRK_ALLOW_FAILURES 3
#endif
#ifndef SBRK_FAILURE_PRICE
# define SBRK_FAILURE_PRICE 50
#endif
#if defined(PERL_EMERGENCY_SBRK) && defined(PERL_CORE)
# ifndef BIG_SIZE
# define BIG_SIZE (1<<16) /* 64K */
# endif
static char *emergency_buffer;
static MEM_SIZE emergency_buffer_size;
static Malloc_t
emergency_sbrk(size)
MEM_SIZE size;
{
if (size >= BIG_SIZE) {
/* Give the possibility to recover: */
MUTEX_UNLOCK(&PL_malloc_mutex);
croak("Out of memory during \"large\" request for %i bytes", size);
}
if (!emergency_buffer) {
dTHR;
/* First offense, give a possibility to recover by dieing. */
/* No malloc involved here: */
GV **gvp = (GV**)hv_fetch(PL_defstash, "^M", 2, 0);
SV *sv;
char *pv;
if (!gvp) gvp = (GV**)hv_fetch(PL_defstash, "\015", 1, 0);
if (!gvp || !(sv = GvSV(*gvp)) || !SvPOK(sv)
|| (SvLEN(sv) < (1<<LOG_OF_MIN_ARENA) - M_OVERHEAD))
return (char *)-1; /* Now die die die... */
/* Got it, now detach SvPV: */
pv = SvPV(sv, PL_na);
/* Check alignment: */
if (((u_bigint)(pv - M_OVERHEAD)) & ((1<<LOG_OF_MIN_ARENA) - 1)) {
PerlIO_puts(PerlIO_stderr(),"Bad alignment of $^M!\n");
return (char *)-1; /* die die die */
}
emergency_buffer = pv - M_OVERHEAD;
emergency_buffer_size = SvLEN(sv) + M_OVERHEAD;
SvPOK_off(sv);
SvREADONLY_on(sv);
MUTEX_UNLOCK(&PL_malloc_mutex);
croak("Out of memory during request for %i bytes", size);
}
else if (emergency_buffer_size >= size) {
emergency_buffer_size -= size;
return emergency_buffer + emergency_buffer_size;
}
return (char *)-1; /* poor guy... */
}
#else /* !(defined(PERL_EMERGENCY_SBRK) && defined(PERL_CORE)) */
# define emergency_sbrk(size) -1
#endif /* !(defined(PERL_EMERGENCY_SBRK) && defined(PERL_CORE)) */
/*
* nextf[i] is the pointer to the next free block of size 2^i. The
* smallest allocatable block is 8 bytes. The overhead information
* precedes the data area returned to the user.
*/
#define NBUCKETS (32*BUCKETS_PER_POW2 + 1)
static union overhead *nextf[NBUCKETS];
#ifdef USE_PERL_SBRK
#define sbrk(a) Perl_sbrk(a)
Malloc_t Perl_sbrk _((int size));
#else
#ifdef DONT_DECLARE_STD
#ifdef I_UNISTD
#include <unistd.h>
#endif
#else
extern Malloc_t sbrk(int);
#endif
#endif
#ifdef DEBUGGING_MSTATS
/*
* nmalloc[i] is the difference between the number of mallocs and frees
* for a given block size.
*/
static u_int nmalloc[NBUCKETS];
static u_int sbrk_slack;
static u_int start_slack;
#endif
static u_int goodsbrk;
#ifdef DEBUGGING
#define ASSERT(p,diag) if (!(p)) botch(diag,STRINGIFY(p)); else
static void
botch(char *diag, char *s)
{
PerlIO_printf(PerlIO_stderr(), "assertion botched (%s?): %s\n", diag, s);
PerlProc_abort();
}
#else
#define ASSERT(p, diag)
#endif
Malloc_t
malloc(register size_t nbytes)
{
register union overhead *p;
register int bucket;
register MEM_SIZE shiftr;
#if defined(DEBUGGING) || defined(RCHECK)
MEM_SIZE size = nbytes;
#endif
BARK_64K_LIMIT("Allocation",nbytes,nbytes);
#ifdef DEBUGGING
if ((long)nbytes < 0)
croak("%s", "panic: malloc");
#endif
MUTEX_LOCK(&PL_malloc_mutex);
/*
* Convert amount of memory requested into
* closest block size stored in hash buckets
* which satisfies request. Account for
* space used per block for accounting.
*/
#ifdef PACK_MALLOC
# ifdef SMALL_BUCKET_VIA_TABLE
if (nbytes == 0)
bucket = MIN_BUCKET;
else if (nbytes <= SIZE_TABLE_MAX) {
bucket = bucket_of[(nbytes - 1) >> BUCKET_TABLE_SHIFT];
} else
# else
if (nbytes == 0)
nbytes = 1;
if (nbytes <= MAX_POW2_ALGO) goto do_shifts;
else
# endif
#endif
{
POW2_OPTIMIZE_ADJUST(nbytes);
nbytes += M_OVERHEAD;
nbytes = (nbytes + 3) &~ 3;
do_shifts:
shiftr = (nbytes - 1) >> START_SHIFT;
bucket = START_SHIFTS_BUCKET;
/* apart from this loop, this is O(1) */
while (shiftr >>= 1)
bucket += BUCKETS_PER_POW2;
}
/*
* If nothing in hash bucket right now,
* request more memory from the system.
*/
if (nextf[bucket] == NULL)
morecore(bucket);
if ((p = nextf[bucket]) == NULL) {
MUTEX_UNLOCK(&PL_malloc_mutex);
#ifdef PERL_CORE
if (!PL_nomemok) {
PerlIO_puts(PerlIO_stderr(),"Out of memory!\n");
my_exit(1);
}
#else
return (NULL);
#endif
}
DEBUG_m(PerlIO_printf(Perl_debug_log,
"0x%lx: (%05lu) malloc %ld bytes\n",
(unsigned long)(p+1), (unsigned long)(PL_an++),
(long)size));
/* remove from linked list */
#if defined(RCHECK)
if (((UV)p) & (MEM_ALIGNBYTES - 1))
PerlIO_printf(PerlIO_stderr(), "Corrupt malloc ptr 0x%lx at 0x%lx\n",
(unsigned long)*((int*)p),(unsigned long)p);
#endif
nextf[bucket] = p->ov_next;
#ifdef IGNORE_SMALL_BAD_FREE
if (bucket >= FIRST_BUCKET_WITH_CHECK)
#endif
OV_MAGIC(p, bucket) = MAGIC;
#ifndef PACK_MALLOC
OV_INDEX(p) = bucket;
#endif
#ifdef RCHECK
/*
* Record allocated size of block and
* bound space with magic numbers.
*/
p->ov_rmagic = RMAGIC;
if (bucket <= MAX_SHORT_BUCKET) {
int i;
nbytes = size + M_OVERHEAD;
p->ov_size = nbytes - 1;
if ((i = nbytes & 3)) {
i = 4 - i;
while (i--)
*((char *)((caddr_t)p + nbytes - RSLOP + i)) = RMAGIC_C;
}
nbytes = (nbytes + 3) &~ 3;
*((u_int *)((caddr_t)p + nbytes - RSLOP)) = RMAGIC;
}
#endif
MUTEX_UNLOCK(&PL_malloc_mutex);
return ((Malloc_t)(p + CHUNK_SHIFT));
}
static char *last_sbrk_top;
static char *last_op; /* This arena can be easily extended. */
static int sbrked_remains;
static int sbrk_good = SBRK_ALLOW_FAILURES * SBRK_FAILURE_PRICE;
#ifdef DEBUGGING_MSTATS
static int sbrks;
#endif
struct chunk_chain_s {
struct chunk_chain_s *next;
MEM_SIZE size;
};
static struct chunk_chain_s *chunk_chain;
static int n_chunks;
static char max_bucket;
/* Cutoff a piece of one of the chunks in the chain. Prefer smaller chunk. */
static void *
get_from_chain(MEM_SIZE size)
{
struct chunk_chain_s *elt = chunk_chain, **oldp = &chunk_chain;
struct chunk_chain_s **oldgoodp = NULL;
long min_remain = LONG_MAX;
while (elt) {
if (elt->size >= size) {
long remains = elt->size - size;
if (remains >= 0 && remains < min_remain) {
oldgoodp = oldp;
min_remain = remains;
}
if (remains == 0) {
break;
}
}
oldp = &( elt->next );
elt = elt->next;
}
if (!oldgoodp) return NULL;
if (min_remain) {
void *ret = *oldgoodp;
struct chunk_chain_s *next = (*oldgoodp)->next;
*oldgoodp = (struct chunk_chain_s *)((char*)ret + size);
(*oldgoodp)->size = min_remain;
(*oldgoodp)->next = next;
return ret;
} else {
void *ret = *oldgoodp;
*oldgoodp = (*oldgoodp)->next;
n_chunks--;
return ret;
}
}
static void
add_to_chain(void *p, MEM_SIZE size, MEM_SIZE chip)
{
struct chunk_chain_s *next = chunk_chain;
char *cp = (char*)p;
cp += chip;
chunk_chain = (struct chunk_chain_s *)cp;
chunk_chain->size = size - chip;
chunk_chain->next = next;
n_chunks++;
}
static void *
get_from_bigger_buckets(int bucket, MEM_SIZE size)
{
int price = 1;
static int bucketprice[NBUCKETS];
while (bucket <= max_bucket) {
/* We postpone stealing from bigger buckets until we want it
often enough. */
if (nextf[bucket] && bucketprice[bucket]++ >= price) {
/* Steal it! */
void *ret = (void*)(nextf[bucket] - 1 + CHUNK_SHIFT);
bucketprice[bucket] = 0;
if (((char*)nextf[bucket]) - M_OVERHEAD == last_op) {
last_op = NULL; /* Disable optimization */
}
nextf[bucket] = nextf[bucket]->ov_next;
#ifdef DEBUGGING_MSTATS
nmalloc[bucket]--;
start_slack -= M_OVERHEAD;
#endif
add_to_chain(ret, (BUCKET_SIZE(bucket) +
POW2_OPTIMIZE_SURPLUS(bucket)),
size);
return ret;
}
bucket++;
}
return NULL;
}
static union overhead *
getpages(int needed, int *nblksp, int bucket)
{
/* Need to do (possibly expensive) system call. Try to
optimize it for rare calling. */
MEM_SIZE require = needed - sbrked_remains;
char *cp;
union overhead *ovp;
int slack = 0;
if (sbrk_good > 0) {
if (!last_sbrk_top && require < FIRST_SBRK)
require = FIRST_SBRK;
else if (require < MIN_SBRK) require = MIN_SBRK;
if (require < goodsbrk * MIN_SBRK_FRAC / 100)
require = goodsbrk * MIN_SBRK_FRAC / 100;
require = ((require - 1 + MIN_SBRK) / MIN_SBRK) * MIN_SBRK;
} else {
require = needed;
last_sbrk_top = 0;
sbrked_remains = 0;
}
DEBUG_m(PerlIO_printf(Perl_debug_log,
"sbrk(%ld) for %ld-byte-long arena\n",
(long)require, (long) needed));
cp = (char *)sbrk(require);
#ifdef DEBUGGING_MSTATS
sbrks++;
#endif
if (cp == last_sbrk_top) {
/* Common case, anything is fine. */
sbrk_good++;
ovp = (union overhead *) (cp - sbrked_remains);
sbrked_remains = require - (needed - sbrked_remains);
} else if (cp == (char *)-1) { /* no more room! */
ovp = (union overhead *)emergency_sbrk(needed);
if (ovp == (union overhead *)-1)
return 0;
return ovp;
} else { /* Non-continuous or first sbrk(). */
long add = sbrked_remains;
char *newcp;
if (sbrked_remains) { /* Put rest into chain, we
cannot use it right now. */
add_to_chain((void*)(last_sbrk_top - sbrked_remains),
sbrked_remains, 0);
}
/* Second, check alignment. */
slack = 0;
#ifndef atarist /* on the atari we dont have to worry about this */
# ifndef I286 /* The sbrk(0) call on the I286 always returns the next segment */
/* CHUNK_SHIFT is 1 for PACK_MALLOC, 0 otherwise. */
if ((UV)cp & (0x7FF >> CHUNK_SHIFT)) { /* Not aligned. */
slack = (0x800 >> CHUNK_SHIFT)
- ((UV)cp & (0x7FF >> CHUNK_SHIFT));
add += slack;
}
# endif
#endif /* atarist */
if (add) {
DEBUG_m(PerlIO_printf(Perl_debug_log,
"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",
(long)add, (long) slack,
(long) sbrked_remains));
newcp = (char *)sbrk(add);
#if defined(DEBUGGING_MSTATS)
sbrks++;
sbrk_slack += add;
#endif
if (newcp != cp + require) {
/* Too bad: even rounding sbrk() is not continuous.*/
DEBUG_m(PerlIO_printf(Perl_debug_log,
"failed to fix bad sbrk()\n"));
#ifdef PACK_MALLOC
if (slack) {
MUTEX_UNLOCK(&PL_malloc_mutex);
croak("%s", "panic: Off-page sbrk");
}
#endif
if (sbrked_remains) {
/* Try again. */
#if defined(DEBUGGING_MSTATS)
sbrk_slack += require;
#endif
require = needed;
DEBUG_m(PerlIO_printf(Perl_debug_log,
"straight sbrk(%ld)\n",
(long)require));
cp = (char *)sbrk(require);
#ifdef DEBUGGING_MSTATS
sbrks++;
#endif
if (cp == (char *)-1)
return 0;
}
sbrk_good = -1; /* Disable optimization!
Continue with not-aligned... */
} else {
cp += slack;
require += sbrked_remains;
}
}
if (last_sbrk_top) {
sbrk_good -= SBRK_FAILURE_PRICE;
}
ovp = (union overhead *) cp;
/*
* Round up to minimum allocation size boundary
* and deduct from block count to reflect.
*/
#ifndef I286 /* Again, this should always be ok on an 80286 */
if ((UV)ovp & 7) {
ovp = (union overhead *)(((UV)ovp + 8) & ~7);
DEBUG_m(PerlIO_printf(Perl_debug_log,
"fixing sbrk(): %d bytes off machine alignement\n",
(int)((UV)ovp & 7)));
(*nblksp)--;