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ceph: make CRUSH hash function a bucket property 

Make the integer hash function a property of the bucket it is used on.  This
allows us to gracefully add support for new hash functions without starting
from scatch.

Signed-off-by: Sage Weil <sage@newdream.net>
This commit is contained in:
Sage Weil 2009-11-07 20:18:22 -08:00
parent 1654dd0cf5
commit fb690390e3
5 changed files with 93 additions and 21 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
fs/ceph/crush/crush.h
View File

@ -102,7 +102,8 @@ extern const char *crush_bucket_alg_name(int alg);
struct crush_bucket {
__s32 id; /* this'll be negative */
__u16 type; /* non-zero; type=0 is reserved for devices */
__u16 alg; /* one of CRUSH_BUCKET_* */
__u8 alg; /* one of CRUSH_BUCKET_* */
__u8 hash; /* which hash function to use, CRUSH_HASH_* */
__u32 weight; /* 16-bit fixed point */
__u32 size; /* num items */
__s32 *items;

73
fs/ceph/crush/hash.c
View File

@ -1,5 +1,6 @@
#include <linux/types.h>
#include "hash.h"
/*
* Robert Jenkins' function for mixing 32-bit values
@ -20,7 +21,7 @@
#define crush_hash_seed 1315423911
__u32 crush_hash32(__u32 a)
static __u32 crush_hash32_rjenkins1(__u32 a)
{
__u32 hash = crush_hash_seed ^ a;
__u32 b = a;
@ -31,7 +32,7 @@ __u32 crush_hash32(__u32 a)
return hash;
}
__u32 crush_hash32_2(__u32 a, __u32 b)
static __u32 crush_hash32_rjenkins1_2(__u32 a, __u32 b)
{
__u32 hash = crush_hash_seed ^ a ^ b;
__u32 x = 231232;
@ -42,7 +43,7 @@ __u32 crush_hash32_2(__u32 a, __u32 b)
return hash;
}
__u32 crush_hash32_3(__u32 a, __u32 b, __u32 c)
static __u32 crush_hash32_rjenkins1_3(__u32 a, __u32 b, __u32 c)
{
__u32 hash = crush_hash_seed ^ a ^ b ^ c;
__u32 x = 231232;
@ -55,7 +56,7 @@ __u32 crush_hash32_3(__u32 a, __u32 b, __u32 c)
return hash;
}
__u32 crush_hash32_4(__u32 a, __u32 b, __u32 c, __u32 d)
static __u32 crush_hash32_rjenkins1_4(__u32 a, __u32 b, __u32 c, __u32 d)
{
__u32 hash = crush_hash_seed ^ a ^ b ^ c ^ d;
__u32 x = 231232;
@ -69,7 +70,8 @@ __u32 crush_hash32_4(__u32 a, __u32 b, __u32 c, __u32 d)
return hash;
}
__u32 crush_hash32_5(__u32 a, __u32 b, __u32 c, __u32 d, __u32 e)
static __u32 crush_hash32_rjenkins1_5(__u32 a, __u32 b, __u32 c, __u32 d,
__u32 e)
{
__u32 hash = crush_hash_seed ^ a ^ b ^ c ^ d ^ e;
__u32 x = 231232;
@ -84,3 +86,64 @@ __u32 crush_hash32_5(__u32 a, __u32 b, __u32 c, __u32 d, __u32 e)
crush_hashmix(y, e, hash);
return hash;
}
__u32 crush_hash32(int type, __u32 a)
{
switch (type) {
case CRUSH_HASH_RJENKINS1:
return crush_hash32_rjenkins1(a);
default:
return 0;
}
}
__u32 crush_hash32_2(int type, __u32 a, __u32 b)
{
switch (type) {
case CRUSH_HASH_RJENKINS1:
return crush_hash32_rjenkins1_2(a, b);
default:
return 0;
}
}
__u32 crush_hash32_3(int type, __u32 a, __u32 b, __u32 c)
{
switch (type) {
case CRUSH_HASH_RJENKINS1:
return crush_hash32_rjenkins1_3(a, b, c);
default:
return 0;
}
}
__u32 crush_hash32_4(int type, __u32 a, __u32 b, __u32 c, __u32 d)
{
switch (type) {
case CRUSH_HASH_RJENKINS1:
return crush_hash32_rjenkins1_4(a, b, c, d);
default:
return 0;
}
}
__u32 crush_hash32_5(int type, __u32 a, __u32 b, __u32 c, __u32 d, __u32 e)
{
switch (type) {
case CRUSH_HASH_RJENKINS1:
return crush_hash32_rjenkins1_5(a, b, c, d, e);
default:
return 0;
}
}
const char *crush_hash_name(int type)
{
switch (type) {
case CRUSH_HASH_RJENKINS1:
return "rjenkins1";
default:
return "unknown";
}
}

19
fs/ceph/crush/hash.h
View File

@ -1,12 +1,17 @@
#ifndef _CRUSH_HASH_H
#define _CRUSH_HASH_H
extern __u32 crush_hash32(__u32 a);
extern __u32 crush_hash32_2(__u32 a, __u32 b);
extern __u32 crush_hash32_3(__u32 a, __u32 b, __u32 c);
extern __u32 crush_hash32_4(__u32 a, __u32 b, __u32 c,
__u32 d);
extern __u32 crush_hash32_5(__u32 a, __u32 b, __u32 c,
__u32 d, __u32 e);
#define CRUSH_HASH_RJENKINS1 0
#define CRUSH_HASH_DEFAULT CRUSH_HASH_RJENKINS1
extern const char *crush_hash_name(int type);
extern __u32 crush_hash32(int type, __u32 a);
extern __u32 crush_hash32_2(int type, __u32 a, __u32 b);
extern __u32 crush_hash32_3(int type, __u32 a, __u32 b, __u32 c);
extern __u32 crush_hash32_4(int type, __u32 a, __u32 b, __u32 c, __u32 d);
extern __u32 crush_hash32_5(int type, __u32 a, __u32 b, __u32 c, __u32 d,
__u32 e);
#endif

16
fs/ceph/crush/mapper.c
View File

@ -78,7 +78,7 @@ static int bucket_perm_choose(struct crush_bucket *bucket,
/* optimize common r=0 case */
if (pr == 0) {
s = crush_hash32_3(x, bucket->id, 0) %
s = crush_hash32_3(bucket->hash, x, bucket->id, 0) %
bucket->size;
bucket->perm[0] = s;
bucket->perm_n = 0xffff; /* magic value, see below */
@ -103,7 +103,7 @@ static int bucket_perm_choose(struct crush_bucket *bucket,
unsigned p = bucket->perm_n;
/* no point in swapping the final entry */
if (p < bucket->size - 1) {
i = crush_hash32_3(x, bucket->id, p) %
i = crush_hash32_3(bucket->hash, x, bucket->id, p) %
(bucket->size - p);
if (i) {
unsigned t = bucket->perm[p + i];
@ -138,8 +138,8 @@ static int bucket_list_choose(struct crush_bucket_list *bucket,
int i;
for (i = bucket->h.size-1; i >= 0; i--) {
__u64 w = crush_hash32_4(x, bucket->h.items[i], r,
bucket->h.id);
__u64 w = crush_hash32_4(bucket->h.hash,x, bucket->h.items[i],
r, bucket->h.id);
w &= 0xffff;
dprintk("list_choose i=%d x=%d r=%d item %d weight %x "
"sw %x rand %llx",
@ -198,7 +198,8 @@ static int bucket_tree_choose(struct crush_bucket_tree *bucket,
while (!terminal(n)) {
/* pick point in [0, w) */
w = bucket->node_weights[n];
t = (__u64)crush_hash32_4(x, n, r, bucket->h.id) * (__u64)w;
t = (__u64)crush_hash32_4(bucket->h.hash, x, n, r,
bucket->h.id) * (__u64)w;
t = t >> 32;
/* descend to the left or right? */
@ -224,7 +225,7 @@ static int bucket_straw_choose(struct crush_bucket_straw *bucket,
__u64 draw;
for (i = 0; i < bucket->h.size; i++) {
draw = crush_hash32_3(x, bucket->h.items[i], r);
draw = crush_hash32_3(bucket->h.hash, x, bucket->h.items[i], r);
draw &= 0xffff;
draw *= bucket->straws[i];
if (i == 0 || draw > high_draw) {
@ -267,7 +268,8 @@ static int is_out(struct crush_map *map, __u32 *weight, int item, int x)
return 0;
if (weight[item] == 0)
return 1;
if ((crush_hash32_2(x, item) & 0xffff) < weight[item])
if ((crush_hash32_2(CRUSH_HASH_RJENKINS1, x, item) & 0xffff)
< weight[item])
return 0;
return 1;
}

3
fs/ceph/osdmap.c
View File

@ -210,7 +210,8 @@ static struct crush_map *crush_decode(void *pbyval, void *end)
ceph_decode_need(p, end, 4*sizeof(u32), bad);
b->id = ceph_decode_32(p);
b->type = ceph_decode_16(p);
b->alg = ceph_decode_16(p);
b->alg = ceph_decode_8(p);
b->hash = ceph_decode_8(p);
b->weight = ceph_decode_32(p);
b->size = ceph_decode_32(p);