*
*/
+/*
+ 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 system-malloc() to emulate sbrk(). Normally only used with broken
+ # sbrk()s.
+ PERL_SBRK_VIA_MALLOC undef
+
+ # 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
+
+ # Which allocator to use if PERL_SBRK_VIA_MALLOC
+ SYSTEM_ALLOC(a) malloc(a)
+
+ 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
# 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 to 15 in 4-byte increments. */
(sizeof(void*) > 4 ? 6 : 5), /* 4/8, 5-th bucket for better reports */
6, /* 8 */
- 7, 8, /* 12, 16 */
+ 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 */
MEM_SIZE
malloced_size(void *p)
{
- int bucket = OV_INDEX((union overhead *)p);
-
+ union overhead *ovp = (union overhead *)
+ ((caddr_t)p - sizeof (union overhead) * CHUNK_SHIFT);
+ int bucket = OV_INDEX(ovp);
+#ifdef RCHECK
+ /* The caller wants to have a complete control over the chunk,
+ disable the memory checking inside the chunk. */
+ if (bucket <= MAX_SHORT_BUCKET) {
+ MEM_SIZE size = BUCKET_SIZE_REAL(bucket);
+ ovp->ov_size = size + M_OVERHEAD - 1;
+ *((u_int *)((caddr_t)ovp + size + M_OVERHEAD - RSLOP)) = RMAGIC;
+ }
+#endif
return BUCKET_SIZE_REAL(bucket);
}
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