#ifdef PERL_CORE
# include "EXTERN.h"
-#define PERL_IN_MALLOC_C
+# define PERL_IN_MALLOC_C
# include "perl.h"
# if defined(PERL_IMPLICIT_CONTEXT)
# define croak Perl_croak_nocontext
# ifndef PERL_GET_INTERP
# define PERL_GET_INTERP PL_curinterp
# endif
+# ifndef Perl_malloc
+# define Perl_malloc malloc
+# endif
+# ifndef Perl_mfree
+# define Perl_mfree free
+# endif
+# ifndef Perl_realloc
+# define Perl_realloc realloc
+# endif
+# ifndef Perl_calloc
+# define Perl_calloc calloc
+# endif
+# ifndef Perl_strdup
+# define Perl_strdup strdup
+# endif
#endif
#ifndef MUTEX_LOCK
* of such *unused* blocks are kept in nextf[i] with big enough i. (nextf
* is an array of linked lists.) (Addresses of used blocks are not known.)
*
- * Moreover, since the algorithm may try to "bite" smaller blocks of out
+ * Moreover, since the algorithm may try to "bite" smaller blocks out
* of unused bigger ones, there are also regions of "irregular" size,
* managed separately, by a linked list chunk_chain.
*
#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.
+/* In this case there are several possible layout of arenas depending
+ * on the size. Arenas are of sizes multiple to 2K, 2K-aligned, and
+ * have a size close to a power of 2.
+ *
+ * Arenas of the size >= 4K keep one chunk only. Arenas of size 2K
+ * may keep one chunk or multiple chunks. Here are the possible
+ * layouts of arenas:
+ *
+ * # One chunk only, chunksize 2^k + SOMETHING - ALIGN, k >= 11
+ *
+ * INDEX MAGIC1 UNUSED CHUNK1
+ *
+ * # Multichunk with sanity checking and chunksize 2^k-ALIGN, k>7
+ *
+ * INDEX MAGIC1 MAGIC2 MAGIC3 UNUSED CHUNK1 CHUNK2 CHUNK3 ...
+ *
+ * # Multichunk with sanity checking and size 2^k-ALIGN, k=7
+ *
+ * INDEX MAGIC1 MAGIC2 MAGIC3 UNUSED CHUNK1 UNUSED CHUNK2 CHUNK3 ...
+ *
+ * # Multichunk with sanity checking and size up to 80
+ *
+ * INDEX UNUSED MAGIC1 UNUSED MAGIC2 UNUSED ... CHUNK1 CHUNK2 CHUNK3 ...
+ *
+ * # No sanity check (usually up to 48=byte-long buckets)
+ * INDEX UNUSED CHUNK1 CHUNK2 ...
+ *
+ * Above INDEX and MAGIC are one-byte-long. Sizes of UNUSED are
+ * appropriate to keep algorithms simple and memory aligned. INDEX
+ * encodes the size of the chunk, while MAGICn encodes state (used,
+ * free or non-managed-by-us-so-it-indicates-a-bug) of CHUNKn. MAGIC
+ * is used for sanity checking purposes only. SOMETHING is 0 or 4K
+ * (to make size of big CHUNK accomodate allocations for powers of two
+ * better).
+ *
+ * [There is no need to alignment between chunks, since C rules ensure
+ * that structs which need 2^k alignment have sizeof which is
+ * divisible by 2^k. Thus as far as the last chunk is aligned at the
+ * end of the arena, and 2K-alignment does not contradict things,
+ * everything is going to be OK for sizes of chunks 2^n and 2^n +
+ * 2^k. Say, 80-bit buckets will be 16-bit aligned, and as far as we
+ * put allocations for requests in 65..80 range, all is fine.
+ *
+ * Note, however, that standard malloc() puts more strict
+ * requirements than the above C rules. Moreover, our algorithms of
+ * realloc() may break this idyll, but we suppose that realloc() does
+ * need not change alignment.]
+ *
+ * Is very important to make calculation of the offset of MAGICm as
+ * quick as possible, since it is done on each malloc()/free(). In
+ * fact it is so quick that it has quite little effect on the speed of
+ * doing malloc()/free(). [By default] We forego such calculations
+ * for small chunks, but only to save extra 3% of memory, not because
+ * of speed considerations.
+ *
+ * Here is the algorithm [which is the same for all the allocations
+ * schemes above], see OV_MAGIC(block,bucket). Let OFFSETm be the
+ * offset of the CHUNKm from the start of ARENA. Then offset of
+ * MAGICm is (OFFSET1 >> SHIFT) + ADDOFFSET. Here SHIFT and ADDOFFSET
+ * are numbers which depend on the size of the chunks only.
+ *
+ * Let as check some sanity conditions. Numbers OFFSETm>>SHIFT are
+ * different for all the chunks in the arena if 2^SHIFT is not greater
+ * than size of the chunks in the arena. MAGIC1 will not overwrite
+ * INDEX provided ADDOFFSET is >0 if OFFSET1 < 2^SHIFT. MAGIClast
+ * will not overwrite CHUNK1 if OFFSET1 > (OFFSETlast >> SHIFT) +
+ * ADDOFFSET.
+ *
+ * Make SHIFT the maximal possible (there is no point in making it
+ * smaller). Since OFFSETlast is 2K - CHUNKSIZE, above restrictions
+ * give restrictions on OFFSET1 and on ADDOFFSET.
+ *
+ * In particular, for chunks of size 2^k with k>=6 we can put
+ * ADDOFFSET to be from 0 to 2^k - 2^(11-k), and have
+ * OFFSET1==chunksize. For chunks of size 80 OFFSET1 of 2K%80=48 is
+ * large enough to have ADDOFFSET between 1 and 16 (similarly for 96,
+ * when ADDOFFSET should be 1). In particular, keeping MAGICs for
+ * these sizes gives no additional size penalty.
+ *
+ * However, for chunks of size 2^k with k<=5 this gives OFFSET1 >=
+ * ADDOFSET + 2^(11-k). Keeping ADDOFFSET 0 allows for 2^(11-k)-2^(11-2k)
+ * chunks per arena. This is smaller than 2^(11-k) - 1 which are
+ * needed if no MAGIC is kept. [In fact, having a negative ADDOFFSET
+ * would allow for slightly more buckets per arena for k=2,3.]
+ *
+ * Similarly, for chunks of size 3/2*2^k with k<=5 MAGICs would span
+ * the area up to 2^(11-k)+ADDOFFSET. For k=4 this give optimal
+ * ADDOFFSET as -7..0. For k=3 ADDOFFSET can go up to 4 (with tiny
+ * savings for negative ADDOFFSET). For k=5 ADDOFFSET can go -1..16
+ * (with no savings for negative values).
*
- * 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).
+ * In particular, keeping ADDOFFSET 0 for sizes of chunks up to 2^6
+ * leads to tiny pessimizations in case of sizes 4, 8, 12, 24, and
+ * leads to no contradictions except for size=80 (or 96.)
*
- * 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.
+ * However, it also makes sense to keep no magic for sizes 48 or less.
+ * This is what we do. In this case one needs ADDOFFSET>=1 also for
+ * chunksizes 12, 24, and 48, unless one gets one less chunk per
+ * arena.
+ *
+ * The algo of OV_MAGIC(block,bucket) keeps ADDOFFSET 0 until
+ * chunksize of 64, then makes it 1.
*
- * 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. */
+ * This allows for an additional optimization: the above scheme leads
+ * to giant overheads for sizes 128 or more (one whole chunk needs to
+ * be sacrifised to keep INDEX). Instead we use chunks not of size
+ * 2^k, but of size 2^k-ALIGN. If we pack these chunks at the end of
+ * the arena, then the beginnings are still in different 2^k-long
+ * sections of the arena if k>=7 for ALIGN==4, and k>=8 if ALIGN=8.
+ * Thus for k>7 the above algo of calculating the offset of the magic
+ * will still give different answers for different chunks. And to
+ * avoid the overrun of MAGIC1 into INDEX, one needs ADDOFFSET of >=1.
+ * In the case k=7 we just move the first chunk an extra ALIGN
+ * backward inside the ARENA (this is done once per arena lifetime,
+ * thus is not a big overhead). */
# 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)
croak("%s", "panic: malloc");
#endif
- MALLOC_LOCK;
/*
* Convert amount of memory requested into
* closest block size stored in hash buckets
while (shiftr >>= 1)
bucket += BUCKETS_PER_POW2;
}
+ MALLOC_LOCK;
/*
* If nothing in hash bucket right now,
* request more memory from the system.
my_exit(1);
}
}
-#else
- return (NULL);
#endif
+ return (NULL);
}
DEBUG_m(PerlIO_printf(Perl_debug_log,
(unsigned long)*((int*)p),(unsigned long)p);
#endif
nextf[bucket] = p->ov_next;
+
+ MALLOC_UNLOCK;
+
#ifdef IGNORE_SMALL_BAD_FREE
if (bucket >= FIRST_BUCKET_WITH_CHECK)
#endif
*((u_int *)((caddr_t)p + nbytes - RSLOP)) = RMAGIC;
}
#endif
- MALLOC_UNLOCK;
return ((Malloc_t)(p + CHUNK_SHIFT));
}
#endif
return; /* sanity */
}
- MALLOC_LOCK;
#ifdef RCHECK
ASSERT(ovp->ov_rmagic == RMAGIC, "chunk's head overwrite");
if (OV_INDEX(ovp) <= MAX_SHORT_BUCKET) {
#endif
ASSERT(OV_INDEX(ovp) < NBUCKETS, "chunk's head overwrite");
size = OV_INDEX(ovp);
+
+ MALLOC_LOCK;
ovp->ov_next = nextf[size];
nextf[size] = ovp;
MALLOC_UNLOCK;
}
-/*
- * When a program attempts "storage compaction" as mentioned in the
- * old malloc man page, it realloc's an already freed block. Usually
- * this is the last block it freed; occasionally it might be farther
- * back. We have to search all the free lists for the block in order
- * to determine its bucket: 1st we make one pass thru the lists
- * checking only the first block in each; if that fails we search
- * ``reall_srchlen'' blocks in each list for a match (the variable
- * is extern so the caller can modify it). If that fails we just copy
- * however many bytes was given to realloc() and hope it's not huge.
- */
-#define reall_srchlen 4 /* 4 should be plenty, -1 =>'s whole list */
+/* There is no need to do any locking in realloc (with an exception of
+ trying to grow in place if we are at the end of the chain).
+ If somebody calls us from a different thread with the same address,
+ we are sole anyway. */
Malloc_t
Perl_realloc(void *mp, size_t nbytes)
char *res;
int prev_bucket;
register int bucket;
- int was_alloced = 0, incr;
+ int incr; /* 1 if does not fit, -1 if "easily" fits in a
+ smaller bucket, otherwise 0. */
char *cp = (char*)mp;
#if defined(DEBUGGING) || !defined(PERL_CORE)
if (!cp)
return Perl_malloc(nbytes);
- MALLOC_LOCK;
ovp = (union overhead *)((caddr_t)cp
- sizeof (union overhead) * CHUNK_SHIFT);
bucket = OV_INDEX(ovp);
+
#ifdef IGNORE_SMALL_BAD_FREE
- if ((bucket < FIRST_BUCKET_WITH_CHECK)
- || (OV_MAGIC(ovp, bucket) == MAGIC))
+ if ((bucket >= FIRST_BUCKET_WITH_CHECK)
+ && (OV_MAGIC(ovp, bucket) != MAGIC))
#else
- if (OV_MAGIC(ovp, bucket) == MAGIC)
+ if (OV_MAGIC(ovp, bucket) != MAGIC)
#endif
- {
- was_alloced = 1;
- } else {
- /*
- * Already free, doing "compaction".
- *
- * Search for the old block of memory on the
- * free list. First, check the most common
- * case (last element free'd), then (this failing)
- * the last ``reall_srchlen'' items free'd.
- * If all lookups fail, then assume the size of
- * the memory block being realloc'd is the
- * smallest possible.
- */
- if ((bucket = findbucket(ovp, 1)) < 0 &&
- (bucket = findbucket(ovp, reall_srchlen)) < 0)
- bucket = 0;
- }
+ {
+ static int bad_free_warn = -1;
+ if (bad_free_warn == -1) {
+ char *pbf = PerlEnv_getenv("PERL_BADFREE");
+ bad_free_warn = (pbf) ? atoi(pbf) : 1;
+ }
+ if (!bad_free_warn)
+ return;
+#ifdef RCHECK
+ warn("%srealloc() %signored",
+ (ovp->ov_rmagic == RMAGIC - 1 ? "" : "Bad "),
+ ovp->ov_rmagic == RMAGIC - 1 ? "of freed memory " : "");
+#else
+ warn("%s", "Bad realloc() ignored");
+#endif
+ return; /* sanity */
+ }
+
onb = BUCKET_SIZE_REAL(bucket);
/*
* avoid the copy if same size block.
incr = 0;
else incr = -1;
}
- if (!was_alloced
#ifdef STRESS_REALLOC
- || 1 /* always do it the hard way */
+ goto hard_way;
#endif
- ) goto hard_way;
- else if (incr == 0) {
+ if (incr == 0) {
inplace_label:
#ifdef RCHECK
/*
}
#endif
res = cp;
- MALLOC_UNLOCK;
DEBUG_m(PerlIO_printf(Perl_debug_log,
"0x%lx: (%05lu) realloc %ld bytes inplace\n",
(unsigned long)res,(unsigned long)(PL_an++),
newarena = (1 << pow) + POW2_OPTIMIZE_SURPLUS(pow * BUCKETS_PER_POW2);
require = newarena - onb - M_OVERHEAD;
- if (getpages_adjacent(require)) {
+ MALLOC_LOCK;
+ if (cp - M_OVERHEAD == last_op /* We *still* are the last chunk */
+ && getpages_adjacent(require)) {
#ifdef DEBUGGING_MSTATS
nmalloc[bucket]--;
nmalloc[pow * BUCKETS_PER_POW2]++;
#endif
*(cp - M_OVERHEAD) = pow * BUCKETS_PER_POW2; /* Fill index. */
+ MALLOC_UNLOCK;
goto inplace_label;
- } else
+ } else {
+ MALLOC_UNLOCK;
goto hard_way;
+ }
} else {
hard_way:
- MALLOC_UNLOCK;
DEBUG_m(PerlIO_printf(Perl_debug_log,
"0x%lx: (%05lu) realloc %ld bytes the hard way\n",
(unsigned long)cp,(unsigned long)(PL_an++),
return (NULL);
if (cp != res) /* common optimization */
Copy(cp, res, (MEM_SIZE)(nbytes<onb?nbytes:onb), char);
- if (was_alloced)
- Perl_mfree(cp);
+ Perl_mfree(cp);
}
return ((Malloc_t)res);
}
return p;
}
+char *
+Perl_strdup(const char *s)
+{
+ MEM_SIZE l = strlen(s);
+ char *s1 = (char *)Perl_malloc(l);
+
+ Copy(s, s1, (MEM_SIZE)l, char);
+ return s1;
+}
+
+#ifdef PERL_CORE
+int
+Perl_putenv(char *a)
+{
+ /* Sometimes system's putenv conflicts with my_setenv() - this is system
+ malloc vs Perl's free(). */
+ dTHX;
+ char *var;
+ char *val = a;
+ MEM_SIZE l;
+ char buf[80];
+
+ while (*val && *val != '=')
+ val++;
+ if (!*val)
+ return -1;
+ l = val - a;
+ if (l < sizeof(buf))
+ var = buf;
+ else
+ var = Perl_malloc(l + 1);
+ Copy(a, var, l, char);
+ val++;
+ my_setenv(var,val);
+ if (var != buf)
+ Perl_mfree(var);
+ return 0;
+}
+# endif
+
MEM_SIZE
Perl_malloced_size(void *p)
{
int topbucket=0, topbucket_ev=0, topbucket_odd=0, totfree=0, total=0;
u_int nfree[NBUCKETS];
int total_chain = 0;
- struct chunk_chain_s* nextchain = chunk_chain;
+ struct chunk_chain_s* nextchain;
+ MALLOC_LOCK;
for (i = MIN_BUCKET ; i < NBUCKETS; i++) {
for (j = 0, p = nextf[i]; p; p = p->ov_next, j++)
;
topbucket = i;
}
}
+ nextchain = chunk_chain;
+ while (nextchain) {
+ total_chain += nextchain->size;
+ nextchain = nextchain->next;
+ }
+ MALLOC_UNLOCK;
if (s)
PerlIO_printf(PerlIO_stderr(),
"Memory allocation statistics %s (buckets %ld(%ld)..%ld(%ld)\n",
nmalloc[i] - nfree[i]);
}
#endif
- while (nextchain) {
- total_chain += nextchain->size;
- nextchain = nextchain->next;
- }
PerlIO_printf(PerlIO_stderr(), "\nTotal sbrk(): %d/%d:%d. Odd ends: pad+heads+chain+tail: %d+%d+%d+%d.\n",
goodsbrk + sbrk_slack, sbrks, sbrk_good, sbrk_slack,
start_slack, total_chain, sbrked_remains);
projects / p5sagit/p5-mst-13.2.git / commitdiff