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MM: Minimum memory allocation must to up to 32 if sizeof pointer is 8-bytes

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This commit is contained in:
Gregory Nutt 2014-11-02 12:11:20 -06:00
parent cc679cc902
commit ef82c280fd
2 changed files with 39 additions and 14 deletions
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11
arch/sim/include/limits.h
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@ -77,10 +77,15 @@
#define LLONG_MAX 9223372036854775807LL
#define ULLONG_MAX 18446744073709551615ULL
/* A pointer is 4 bytes */
/* A pointer is 4 or 8 bytes */
#define PTR_MIN (-PTR_MAX - 1)
#define PTR_MAX 2147483647
#define UPTR_MAX 4294967295U
#if !defined(CONFIG_HOST_X86_64) || defined(CONFIG_SIM_M32)
# define PTR_MAX 2147483647
# define UPTR_MAX 4294967295U
#else
# define PTR_MAX 9223372036854775807LL
# define UPTR_MAX 18446744073709551615ULL
#endif
#endif /* __ARCH_SIM_INCLUDE_LIMITS_H */

42
include/nuttx/mm/mm.h
View File

@ -112,24 +112,44 @@
/* These definitions define the characteristics of allocator
*
* MM_MIN_SHIFT is used to define MM_MIN_CHUNK.
* MM_MIN_CHUNK - is the smallest physical chunk that can
* be allocated. It must be at least a large as
* sizeof(struct mm_freenode_s). Larger values may
* improve performance slightly, but will waste memory
* due to quantization losses.
* MM_MIN_CHUNK - is the smallest physical chunk that can be allocated. It
* must be at least a large as sizeof(struct mm_freenode_s). Larger values
* may improve performance slightly, but will waste memory due to
* quantization losses.
*
* MM_MAX_SHIFT is used to define MM_MAX_CHUNK
* MM_MAX_CHUNK is the largest, contiguous chunk of memory
* that can be allocated. It can range from 16-bytes to
* 4Gb. Larger values of MM_MAX_SHIFT can cause larger
* data structure sizes and, perhaps, minor performance
* losses.
* MM_MAX_CHUNK is the largest, contiguous chunk of memory that can be
* allocated. It can range from 16-bytes to 4Gb. Larger values of
* MM_MAX_SHIFT can cause larger data structure sizes and, perhaps,
* minor performance losses.
*/
#if defined(CONFIG_MM_SMALL) && UINTPTR_MAX <= UINT32_MAX
/* Two byte offsets; Pointers may be 2 or 4 bytes;
* sizeof(struct mm_freenode_s) is 8 or 12 bytes.
* REVISIT: We could do better on machines with 16-bit addressing.
*/
#ifdef CONFIG_MM_SMALL
# define MM_MIN_SHIFT 4 /* 16 bytes */
# define MM_MAX_SHIFT 15 /* 32 Kb */
#elif defined(CONFIG_HAVE_LONG_LONG)
/* Four byte offsets; Pointers may be 4 or 8 bytes
* sizeof(struct mm_freenode_s) is 16 or 24 bytes.
*/
# if UINTPTR_MAX <= UINT32_MAX
# define MM_MIN_SHIFT 4 /* 16 bytes */
# elif UINTPTR_MAX <= UINT64_MAX
# define MM_MIN_SHIFT 5 /* 32 bytes */
# endif
# define MM_MAX_SHIFT 22 /* 4 Mb */
#else
/* Four byte offsets; Pointers must be 4 bytes.
* sizeof(struct mm_freenode_s) is 16 bytes.
*/
# define MM_MIN_SHIFT 4 /* 16 bytes */
# define MM_MAX_SHIFT 22 /* 4 Mb */
#endif