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1 | #ifndef CEPH_CRUSH_CRUSH_H |
2 | #define CEPH_CRUSH_CRUSH_H | |
5ecc0a0f | 3 | |
b459be73 ID |
4 | #ifdef __KERNEL__ |
5 | # include <linux/types.h> | |
6 | #else | |
7 | # include "crush_compat.h" | |
8 | #endif | |
5ecc0a0f SW |
9 | |
10 | /* | |
11 | * CRUSH is a pseudo-random data distribution algorithm that | |
12 | * efficiently distributes input values (typically, data objects) | |
13 | * across a heterogeneous, structured storage cluster. | |
14 | * | |
15 | * The algorithm was originally described in detail in this paper | |
16 | * (although the algorithm has evolved somewhat since then): | |
17 | * | |
18 | * http://www.ssrc.ucsc.edu/Papers/weil-sc06.pdf | |
19 | * | |
20 | * LGPL2 | |
21 | */ | |
22 | ||
23 | ||
24 | #define CRUSH_MAGIC 0x00010000ul /* for detecting algorithm revisions */ | |
25 | ||
5ecc0a0f | 26 | #define CRUSH_MAX_DEPTH 10 /* max crush hierarchy depth */ |
b459be73 ID |
27 | #define CRUSH_MAX_RULESET (1<<8) /* max crush ruleset number */ |
28 | #define CRUSH_MAX_RULES CRUSH_MAX_RULESET /* should be the same as max rulesets */ | |
5ecc0a0f | 29 | |
b459be73 ID |
30 | #define CRUSH_MAX_DEVICE_WEIGHT (100u * 0x10000u) |
31 | #define CRUSH_MAX_BUCKET_WEIGHT (65535u * 0x10000u) | |
5ecc0a0f | 32 | |
9a3b490a ID |
33 | #define CRUSH_ITEM_UNDEF 0x7ffffffe /* undefined result (internal use only) */ |
34 | #define CRUSH_ITEM_NONE 0x7fffffff /* no result */ | |
c6d98a60 | 35 | |
5ecc0a0f SW |
36 | /* |
37 | * CRUSH uses user-defined "rules" to describe how inputs should be | |
38 | * mapped to devices. A rule consists of sequence of steps to perform | |
39 | * to generate the set of output devices. | |
40 | */ | |
41 | struct crush_rule_step { | |
42 | __u32 op; | |
43 | __s32 arg1; | |
44 | __s32 arg2; | |
45 | }; | |
46 | ||
47 | /* step op codes */ | |
48 | enum { | |
49 | CRUSH_RULE_NOOP = 0, | |
50 | CRUSH_RULE_TAKE = 1, /* arg1 = value to start with */ | |
51 | CRUSH_RULE_CHOOSE_FIRSTN = 2, /* arg1 = num items to pick */ | |
52 | /* arg2 = type */ | |
53 | CRUSH_RULE_CHOOSE_INDEP = 3, /* same */ | |
54 | CRUSH_RULE_EMIT = 4, /* no args */ | |
917edad5 ID |
55 | CRUSH_RULE_CHOOSELEAF_FIRSTN = 6, |
56 | CRUSH_RULE_CHOOSELEAF_INDEP = 7, | |
be3226ac | 57 | |
cc10df4a | 58 | CRUSH_RULE_SET_CHOOSE_TRIES = 8, /* override choose_total_tries */ |
917edad5 | 59 | CRUSH_RULE_SET_CHOOSELEAF_TRIES = 9, /* override chooseleaf_descend_once */ |
f046bf92 ID |
60 | CRUSH_RULE_SET_CHOOSE_LOCAL_TRIES = 10, |
61 | CRUSH_RULE_SET_CHOOSE_LOCAL_FALLBACK_TRIES = 11, | |
dc6ae6d8 ID |
62 | CRUSH_RULE_SET_CHOOSELEAF_VARY_R = 12, |
63 | CRUSH_RULE_SET_CHOOSELEAF_STABLE = 13 | |
5ecc0a0f SW |
64 | }; |
65 | ||
66 | /* | |
67 | * for specifying choose num (arg1) relative to the max parameter | |
68 | * passed to do_rule | |
69 | */ | |
70 | #define CRUSH_CHOOSE_N 0 | |
71 | #define CRUSH_CHOOSE_N_MINUS(x) (-(x)) | |
72 | ||
73 | /* | |
74 | * The rule mask is used to describe what the rule is intended for. | |
75 | * Given a ruleset and size of output set, we search through the | |
76 | * rule list for a matching rule_mask. | |
77 | */ | |
78 | struct crush_rule_mask { | |
79 | __u8 ruleset; | |
80 | __u8 type; | |
81 | __u8 min_size; | |
82 | __u8 max_size; | |
83 | }; | |
84 | ||
85 | struct crush_rule { | |
86 | __u32 len; | |
87 | struct crush_rule_mask mask; | |
88 | struct crush_rule_step steps[0]; | |
89 | }; | |
90 | ||
91 | #define crush_rule_size(len) (sizeof(struct crush_rule) + \ | |
92 | (len)*sizeof(struct crush_rule_step)) | |
93 | ||
94 | ||
95 | ||
96 | /* | |
97 | * A bucket is a named container of other items (either devices or | |
98 | * other buckets). Items within a bucket are chosen using one of a | |
99 | * few different algorithms. The table summarizes how the speed of | |
100 | * each option measures up against mapping stability when items are | |
101 | * added or removed. | |
102 | * | |
103 | * Bucket Alg Speed Additions Removals | |
104 | * ------------------------------------------------ | |
105 | * uniform O(1) poor poor | |
106 | * list O(n) optimal poor | |
107 | * tree O(log n) good good | |
958a2765 ID |
108 | * straw O(n) better better |
109 | * straw2 O(n) optimal optimal | |
5ecc0a0f SW |
110 | */ |
111 | enum { | |
112 | CRUSH_BUCKET_UNIFORM = 1, | |
113 | CRUSH_BUCKET_LIST = 2, | |
114 | CRUSH_BUCKET_TREE = 3, | |
958a2765 ID |
115 | CRUSH_BUCKET_STRAW = 4, |
116 | CRUSH_BUCKET_STRAW2 = 5, | |
5ecc0a0f | 117 | }; |
c6cf7263 | 118 | extern const char *crush_bucket_alg_name(int alg); |
5ecc0a0f | 119 | |
b459be73 ID |
120 | /* |
121 | * although tree was a legacy algorithm, it has been buggy, so | |
122 | * exclude it. | |
123 | */ | |
124 | #define CRUSH_LEGACY_ALLOWED_BUCKET_ALGS ( \ | |
125 | (1 << CRUSH_BUCKET_UNIFORM) | \ | |
126 | (1 << CRUSH_BUCKET_LIST) | \ | |
127 | (1 << CRUSH_BUCKET_STRAW)) | |
128 | ||
5ecc0a0f SW |
129 | struct crush_bucket { |
130 | __s32 id; /* this'll be negative */ | |
131 | __u16 type; /* non-zero; type=0 is reserved for devices */ | |
fb690390 SW |
132 | __u8 alg; /* one of CRUSH_BUCKET_* */ |
133 | __u8 hash; /* which hash function to use, CRUSH_HASH_* */ | |
5ecc0a0f SW |
134 | __u32 weight; /* 16-bit fixed point */ |
135 | __u32 size; /* num items */ | |
136 | __s32 *items; | |
137 | ||
138 | /* | |
139 | * cached random permutation: used for uniform bucket and for | |
140 | * the linear search fallback for the other bucket types. | |
141 | */ | |
142 | __u32 perm_x; /* @x for which *perm is defined */ | |
143 | __u32 perm_n; /* num elements of *perm that are permuted/defined */ | |
144 | __u32 *perm; | |
145 | }; | |
146 | ||
147 | struct crush_bucket_uniform { | |
148 | struct crush_bucket h; | |
149 | __u32 item_weight; /* 16-bit fixed point; all items equally weighted */ | |
150 | }; | |
151 | ||
152 | struct crush_bucket_list { | |
153 | struct crush_bucket h; | |
154 | __u32 *item_weights; /* 16-bit fixed point */ | |
155 | __u32 *sum_weights; /* 16-bit fixed point. element i is sum | |
156 | of weights 0..i, inclusive */ | |
157 | }; | |
158 | ||
159 | struct crush_bucket_tree { | |
160 | struct crush_bucket h; /* note: h.size is _tree_ size, not number of | |
161 | actual items */ | |
162 | __u8 num_nodes; | |
163 | __u32 *node_weights; | |
164 | }; | |
165 | ||
166 | struct crush_bucket_straw { | |
167 | struct crush_bucket h; | |
168 | __u32 *item_weights; /* 16-bit fixed point */ | |
169 | __u32 *straws; /* 16-bit fixed point */ | |
170 | }; | |
171 | ||
958a2765 ID |
172 | struct crush_bucket_straw2 { |
173 | struct crush_bucket h; | |
174 | __u32 *item_weights; /* 16-bit fixed point */ | |
175 | }; | |
176 | ||
5ecc0a0f SW |
177 | |
178 | ||
179 | /* | |
180 | * CRUSH map includes all buckets, rules, etc. | |
181 | */ | |
182 | struct crush_map { | |
183 | struct crush_bucket **buckets; | |
184 | struct crush_rule **rules; | |
185 | ||
5ecc0a0f SW |
186 | __s32 max_buckets; |
187 | __u32 max_rules; | |
188 | __s32 max_devices; | |
546f04ef SW |
189 | |
190 | /* choose local retries before re-descent */ | |
191 | __u32 choose_local_tries; | |
192 | /* choose local attempts using a fallback permutation before | |
193 | * re-descent */ | |
194 | __u32 choose_local_fallback_tries; | |
b459be73 | 195 | /* choose attempts before giving up */ |
546f04ef | 196 | __u32 choose_total_tries; |
f18650ac ID |
197 | /* attempt chooseleaf inner descent once for firstn mode; on |
198 | * reject retry outer descent. Note that this does *not* | |
199 | * apply to a collision: in that case we will retry as we used | |
200 | * to. */ | |
1604f488 | 201 | __u32 chooseleaf_descend_once; |
e2b149cc ID |
202 | |
203 | /* if non-zero, feed r into chooseleaf, bit-shifted right by (r-1) | |
204 | * bits. a value of 1 is best for new clusters. for legacy clusters | |
205 | * that want to limit reshuffling, a value of 3 or 4 will make the | |
206 | * mappings line up a bit better with previous mappings. */ | |
207 | __u8 chooseleaf_vary_r; | |
b459be73 | 208 | |
dc6ae6d8 ID |
209 | /* if true, it makes chooseleaf firstn to return stable results (if |
210 | * no local retry) so that data migrations would be optimal when some | |
211 | * device fails. */ | |
212 | __u8 chooseleaf_stable; | |
213 | ||
b459be73 ID |
214 | #ifndef __KERNEL__ |
215 | /* | |
216 | * version 0 (original) of straw_calc has various flaws. version 1 | |
217 | * fixes a few of them. | |
218 | */ | |
219 | __u8 straw_calc_version; | |
220 | ||
221 | /* | |
222 | * allowed bucket algs is a bitmask, here the bit positions | |
223 | * are CRUSH_BUCKET_*. note that these are *bits* and | |
224 | * CRUSH_BUCKET_* values are not, so we need to or together (1 | |
225 | * << CRUSH_BUCKET_WHATEVER). The 0th bit is not used to | |
226 | * minimize confusion (bucket type values start at 1). | |
227 | */ | |
228 | __u32 allowed_bucket_algs; | |
229 | ||
230 | __u32 *choose_tries; | |
231 | #endif | |
5ecc0a0f SW |
232 | }; |
233 | ||
234 | ||
235 | /* crush.c */ | |
8b12d47b | 236 | extern int crush_get_bucket_item_weight(const struct crush_bucket *b, int pos); |
5ecc0a0f SW |
237 | extern void crush_destroy_bucket_uniform(struct crush_bucket_uniform *b); |
238 | extern void crush_destroy_bucket_list(struct crush_bucket_list *b); | |
239 | extern void crush_destroy_bucket_tree(struct crush_bucket_tree *b); | |
240 | extern void crush_destroy_bucket_straw(struct crush_bucket_straw *b); | |
958a2765 | 241 | extern void crush_destroy_bucket_straw2(struct crush_bucket_straw2 *b); |
5ecc0a0f | 242 | extern void crush_destroy_bucket(struct crush_bucket *b); |
bfb16d7d | 243 | extern void crush_destroy_rule(struct crush_rule *r); |
5ecc0a0f SW |
244 | extern void crush_destroy(struct crush_map *map); |
245 | ||
f671d4cd SW |
246 | static inline int crush_calc_tree_node(int i) |
247 | { | |
248 | return ((i+1) << 1)-1; | |
249 | } | |
250 | ||
5ecc0a0f | 251 | #endif |