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Increase the small size slabs a bit.

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Move 64Bit integer hashing function to common file for use in other places.
This commit is contained in:
Moinak Ghosh 2012-07-29 15:02:51 +05:30
parent a6f3756e68
commit 7ff2cb74c4
3 changed files with 24 additions and 23 deletions
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10
allocator.c
View file

@ -51,20 +51,20 @@
#ifndef DEBUG_NO_SLAB
/*
* Number of slabs:
* 256 bytes to 1M in power of 2 steps: 13
* 64 bytes to 1M in power of 2 steps: 15
* 1M to 128M in linear steps of 1M: 128
* 200 dynamic slab slots: 200
*
* By doing this we try to get reasonable memory usage while not
* sacrificing performance.
*/
#define NUM_POW2 13
#define NUM_POW2 15
#define NUM_LINEAR 128
#define NUM_SLAB_HASH 200 /* Dynamic slabs hashtable size. */
#define NUM_SLABS (NUM_POW2 + NUM_LINEAR + NUM_SLAB_HASH)
#define SLAB_POS_HASH (NUM_POW2 + NUM_LINEAR)
#define SLAB_START_SZ 256 /* Starting slab size in Bytes. */
#define SLAB_START_POW2 8 /* 2 ^ SLAB_START_POW2 = SLAB_START. */
#define SLAB_START_SZ 64 /* Starting slab size in Bytes. */
#define SLAB_START_POW2 6 /* 2 ^ SLAB_START_POW2 = SLAB_START. */
#define HTABLE_SZ 8192
#define ONEM (1UL * 1024UL * 1024UL)
@ -376,7 +376,7 @@ slab_alloc(void *p, size_t size)
if (!slab) {
if (size <= ONEM) {
/* First eleven slots are power of 2 sizes upto 1M. */
/* First fifteen slots are power of 2 sizes upto 1M. */
slab = &slabheads[find_slot(size)];
} else {
/* Next slots are in intervals of 1M. */

17
utils.c
View file

@ -169,23 +169,6 @@ bytes_to_size(uint64_t bytes)
return (num);
}
/*
* Hash function for 64Bit pointers that generates a 32Bit hash value.
* Taken from Thomas Wang's Integer hashing paper:
* http://www.cris.com/~Ttwang/tech/inthash.htm
*/
uint32_t
hash6432shift(uint64_t key)
{
key = (~key) + (key << 18); // key = (key << 18) - key - 1;
key = key ^ (key >> 31);
key = key * 21; // key = (key + (key << 2)) + (key << 4);
key = key ^ (key >> 11);
key = key + (key << 6);
key = key ^ (key >> 22);
return (uint32_t) key;
}
/*
* Read/Write helpers to ensure a full chunk is read or written
* unless there is an error.

20
utils.h
View file

@ -102,7 +102,6 @@ extern void err_exit(int show_errno, const char *format, ...);
extern const char *get_execname(const char *);
extern int parse_numeric(ssize_t *val, const char *str);
extern char *bytes_to_size(uint64_t bytes);
extern uint32_t hash6432shift(uint64_t key);
extern ssize_t Read(int fd, void *buf, size_t count);
extern ssize_t Read_Adjusted(int fd, uchar_t *buf, size_t count,
ssize_t *rabin_count, void *ctx);
@ -134,6 +133,25 @@ roundup_pow_two(unsigned int v) {
return (v);
}
/*
* Hash function for 64Bit pointers/numbers that generates
* a 32Bit hash value.
* Taken from Thomas Wang's Integer hashing paper:
* http://www.cris.com/~Ttwang/tech/inthash.htm
*/
static uint32_t
hash6432shift(uint64_t key)
{
key = (~key) + (key << 18); // key = (key << 18) - key - 1;
key = key ^ (key >> 31);
key = key * 21; // key = (key + (key << 2)) + (key << 4);
key = key ^ (key >> 11);
key = key + (key << 6);
key = key ^ (key >> 22);
return (uint32_t) key;
}
#ifdef __cplusplus
}
#endif