Steven Rostedt (VMware) | bb730b58 | 2018-08-16 11:26:55 -0400 | [diff] [blame] | 1 | // SPDX-License-Identifier: GPL-2.0 |
Tom Zanussi | 08d43a5 | 2015-12-10 12:50:50 -0600 | [diff] [blame] | 2 | #ifndef __TRACING_MAP_H |
| 3 | #define __TRACING_MAP_H |
| 4 | |
| 5 | #define TRACING_MAP_BITS_DEFAULT 11 |
| 6 | #define TRACING_MAP_BITS_MAX 17 |
| 7 | #define TRACING_MAP_BITS_MIN 7 |
| 8 | |
Tom Zanussi | 4f36c2d | 2017-09-22 14:58:19 -0500 | [diff] [blame] | 9 | #define TRACING_MAP_KEYS_MAX 3 |
Tom Zanussi | 3b772b9 | 2016-03-03 12:54:41 -0600 | [diff] [blame] | 10 | #define TRACING_MAP_VALS_MAX 3 |
| 11 | #define TRACING_MAP_FIELDS_MAX (TRACING_MAP_KEYS_MAX + \ |
| 12 | TRACING_MAP_VALS_MAX) |
Tom Zanussi | 2734b62 | 2018-01-15 20:51:46 -0600 | [diff] [blame] | 13 | #define TRACING_MAP_VARS_MAX 16 |
Tom Zanussi | 08d43a5 | 2015-12-10 12:50:50 -0600 | [diff] [blame] | 14 | #define TRACING_MAP_SORT_KEYS_MAX 2 |
| 15 | |
| 16 | typedef int (*tracing_map_cmp_fn_t) (void *val_a, void *val_b); |
| 17 | |
| 18 | /* |
| 19 | * This is an overview of the tracing_map data structures and how they |
| 20 | * relate to the tracing_map API. The details of the algorithms |
| 21 | * aren't discussed here - this is just a general overview of the data |
| 22 | * structures and how they interact with the API. |
| 23 | * |
| 24 | * The central data structure of the tracing_map is an initially |
| 25 | * zeroed array of struct tracing_map_entry (stored in the map field |
| 26 | * of struct tracing_map). tracing_map_entry is a very simple data |
| 27 | * structure containing only two fields: a 32-bit unsigned 'key' |
| 28 | * variable and a pointer named 'val'. This array of struct |
| 29 | * tracing_map_entry is essentially a hash table which will be |
| 30 | * modified by a single function, tracing_map_insert(), but which can |
| 31 | * be traversed and read by a user at any time (though the user does |
| 32 | * this indirectly via an array of tracing_map_sort_entry - see the |
| 33 | * explanation of that data structure in the discussion of the |
| 34 | * sorting-related data structures below). |
| 35 | * |
| 36 | * The central function of the tracing_map API is |
| 37 | * tracing_map_insert(). tracing_map_insert() hashes the |
| 38 | * arbitrarily-sized key passed into it into a 32-bit unsigned key. |
| 39 | * It then uses this key, truncated to the array size, as an index |
| 40 | * into the array of tracing_map_entries. If the value of the 'key' |
| 41 | * field of the tracing_map_entry found at that location is 0, then |
| 42 | * that entry is considered to be free and can be claimed, by |
| 43 | * replacing the 0 in the 'key' field of the tracing_map_entry with |
| 44 | * the new 32-bit hashed key. Once claimed, that tracing_map_entry's |
| 45 | * 'val' field is then used to store a unique element which will be |
| 46 | * forever associated with that 32-bit hashed key in the |
| 47 | * tracing_map_entry. |
| 48 | * |
| 49 | * That unique element now in the tracing_map_entry's 'val' field is |
| 50 | * an instance of tracing_map_elt, where 'elt' in the latter part of |
| 51 | * that variable name is short for 'element'. The purpose of a |
Steven Rostedt (Red Hat) | 8d44f2f | 2016-02-19 14:47:00 -0500 | [diff] [blame] | 52 | * tracing_map_elt is to hold values specific to the particular |
Tom Zanussi | 08d43a5 | 2015-12-10 12:50:50 -0600 | [diff] [blame] | 53 | * 32-bit hashed key it's assocated with. Things such as the unique |
| 54 | * set of aggregated sums associated with the 32-bit hashed key, along |
| 55 | * with a copy of the full key associated with the entry, and which |
| 56 | * was used to produce the 32-bit hashed key. |
| 57 | * |
| 58 | * When tracing_map_create() is called to create the tracing map, the |
| 59 | * user specifies (indirectly via the map_bits param, the details are |
| 60 | * unimportant for this discussion) the maximum number of elements |
| 61 | * that the map can hold (stored in the max_elts field of struct |
| 62 | * tracing_map). This is the maximum possible number of |
| 63 | * tracing_map_entries in the tracing_map_entry array which can be |
| 64 | * 'claimed' as described in the above discussion, and therefore is |
| 65 | * also the maximum number of tracing_map_elts that can be associated |
| 66 | * with the tracing_map_entry array in the tracing_map. Because of |
| 67 | * the way the insertion algorithm works, the size of the allocated |
| 68 | * tracing_map_entry array is always twice the maximum number of |
| 69 | * elements (2 * max_elts). This value is stored in the map_size |
| 70 | * field of struct tracing_map. |
| 71 | * |
| 72 | * Because tracing_map_insert() needs to work from any context, |
| 73 | * including from within the memory allocation functions themselves, |
| 74 | * both the tracing_map_entry array and a pool of max_elts |
| 75 | * tracing_map_elts are pre-allocated before any call is made to |
| 76 | * tracing_map_insert(). |
| 77 | * |
| 78 | * The tracing_map_entry array is allocated as a single block by |
| 79 | * tracing_map_create(). |
| 80 | * |
| 81 | * Because the tracing_map_elts are much larger objects and can't |
| 82 | * generally be allocated together as a single large array without |
| 83 | * failure, they're allocated individually, by tracing_map_init(). |
| 84 | * |
| 85 | * The pool of tracing_map_elts are allocated by tracing_map_init() |
| 86 | * rather than by tracing_map_create() because at the time |
| 87 | * tracing_map_create() is called, there isn't enough information to |
| 88 | * create the tracing_map_elts. Specifically,the user first needs to |
| 89 | * tell the tracing_map implementation how many fields the |
| 90 | * tracing_map_elts contain, and which types of fields they are (key |
| 91 | * or sum). The user does this via the tracing_map_add_sum_field() |
| 92 | * and tracing_map_add_key_field() functions, following which the user |
| 93 | * calls tracing_map_init() to finish up the tracing map setup. The |
| 94 | * array holding the pointers which make up the pre-allocated pool of |
| 95 | * tracing_map_elts is allocated as a single block and is stored in |
| 96 | * the elts field of struct tracing_map. |
| 97 | * |
| 98 | * There is also a set of structures used for sorting that might |
| 99 | * benefit from some minimal explanation. |
| 100 | * |
| 101 | * struct tracing_map_sort_key is used to drive the sort at any given |
| 102 | * time. By 'any given time' we mean that a different |
| 103 | * tracing_map_sort_key will be used at different times depending on |
| 104 | * whether the sort currently being performed is a primary or a |
| 105 | * secondary sort. |
| 106 | * |
| 107 | * The sort key is very simple, consisting of the field index of the |
| 108 | * tracing_map_elt field to sort on (which the user saved when adding |
| 109 | * the field), and whether the sort should be done in an ascending or |
| 110 | * descending order. |
| 111 | * |
| 112 | * For the convenience of the sorting code, a tracing_map_sort_entry |
| 113 | * is created for each tracing_map_elt, again individually allocated |
| 114 | * to avoid failures that might be expected if allocated as a single |
| 115 | * large array of struct tracing_map_sort_entry. |
| 116 | * tracing_map_sort_entry instances are the objects expected by the |
| 117 | * various internal sorting functions, and are also what the user |
| 118 | * ultimately receives after calling tracing_map_sort_entries(). |
| 119 | * Because it doesn't make sense for users to access an unordered and |
| 120 | * sparsely populated tracing_map directly, the |
| 121 | * tracing_map_sort_entries() function is provided so that users can |
| 122 | * retrieve a sorted list of all existing elements. In addition to |
| 123 | * the associated tracing_map_elt 'elt' field contained within the |
| 124 | * tracing_map_sort_entry, which is the object of interest to the |
| 125 | * user, tracing_map_sort_entry objects contain a number of additional |
| 126 | * fields which are used for caching and internal purposes and can |
| 127 | * safely be ignored. |
| 128 | */ |
| 129 | |
| 130 | struct tracing_map_field { |
| 131 | tracing_map_cmp_fn_t cmp_fn; |
| 132 | union { |
| 133 | atomic64_t sum; |
| 134 | unsigned int offset; |
| 135 | }; |
| 136 | }; |
| 137 | |
| 138 | struct tracing_map_elt { |
| 139 | struct tracing_map *map; |
| 140 | struct tracing_map_field *fields; |
Tom Zanussi | 2734b62 | 2018-01-15 20:51:46 -0600 | [diff] [blame] | 141 | atomic64_t *vars; |
| 142 | bool *var_set; |
Tom Zanussi | 08d43a5 | 2015-12-10 12:50:50 -0600 | [diff] [blame] | 143 | void *key; |
| 144 | void *private_data; |
| 145 | }; |
| 146 | |
| 147 | struct tracing_map_entry { |
| 148 | u32 key; |
| 149 | struct tracing_map_elt *val; |
| 150 | }; |
| 151 | |
| 152 | struct tracing_map_sort_key { |
| 153 | unsigned int field_idx; |
| 154 | bool descending; |
| 155 | }; |
| 156 | |
| 157 | struct tracing_map_sort_entry { |
| 158 | void *key; |
| 159 | struct tracing_map_elt *elt; |
| 160 | bool elt_copied; |
| 161 | bool dup; |
| 162 | }; |
| 163 | |
| 164 | struct tracing_map_array { |
| 165 | unsigned int entries_per_page; |
| 166 | unsigned int entry_size_shift; |
| 167 | unsigned int entry_shift; |
| 168 | unsigned int entry_mask; |
| 169 | unsigned int n_pages; |
| 170 | void **pages; |
| 171 | }; |
| 172 | |
| 173 | #define TRACING_MAP_ARRAY_ELT(array, idx) \ |
| 174 | (array->pages[idx >> array->entry_shift] + \ |
| 175 | ((idx & array->entry_mask) << array->entry_size_shift)) |
| 176 | |
| 177 | #define TRACING_MAP_ENTRY(array, idx) \ |
| 178 | ((struct tracing_map_entry *)TRACING_MAP_ARRAY_ELT(array, idx)) |
| 179 | |
| 180 | #define TRACING_MAP_ELT(array, idx) \ |
| 181 | ((struct tracing_map_elt **)TRACING_MAP_ARRAY_ELT(array, idx)) |
| 182 | |
| 183 | struct tracing_map { |
| 184 | unsigned int key_size; |
| 185 | unsigned int map_bits; |
| 186 | unsigned int map_size; |
| 187 | unsigned int max_elts; |
| 188 | atomic_t next_elt; |
| 189 | struct tracing_map_array *elts; |
| 190 | struct tracing_map_array *map; |
| 191 | const struct tracing_map_ops *ops; |
| 192 | void *private_data; |
| 193 | struct tracing_map_field fields[TRACING_MAP_FIELDS_MAX]; |
| 194 | unsigned int n_fields; |
| 195 | int key_idx[TRACING_MAP_KEYS_MAX]; |
| 196 | unsigned int n_keys; |
| 197 | struct tracing_map_sort_key sort_key; |
Tom Zanussi | 2734b62 | 2018-01-15 20:51:46 -0600 | [diff] [blame] | 198 | unsigned int n_vars; |
Tom Zanussi | 08d43a5 | 2015-12-10 12:50:50 -0600 | [diff] [blame] | 199 | atomic64_t hits; |
| 200 | atomic64_t drops; |
| 201 | }; |
| 202 | |
| 203 | /** |
| 204 | * struct tracing_map_ops - callbacks for tracing_map |
| 205 | * |
| 206 | * The methods in this structure define callback functions for various |
| 207 | * operations on a tracing_map or objects related to a tracing_map. |
| 208 | * |
| 209 | * For a detailed description of tracing_map_elt objects please see |
| 210 | * the overview of tracing_map data structures at the beginning of |
| 211 | * this file. |
| 212 | * |
| 213 | * All the methods below are optional. |
| 214 | * |
| 215 | * @elt_alloc: When a tracing_map_elt is allocated, this function, if |
| 216 | * defined, will be called and gives clients the opportunity to |
| 217 | * allocate additional data and attach it to the element |
| 218 | * (tracing_map_elt->private_data is meant for that purpose). |
| 219 | * Element allocation occurs before tracing begins, when the |
| 220 | * tracing_map_init() call is made by client code. |
| 221 | * |
Tom Zanussi | 08d43a5 | 2015-12-10 12:50:50 -0600 | [diff] [blame] | 222 | * @elt_free: When a tracing_map_elt is freed, this function is called |
| 223 | * and allows client-allocated per-element data to be freed. |
| 224 | * |
| 225 | * @elt_clear: This callback allows per-element client-defined data to |
| 226 | * be cleared, if applicable. |
| 227 | * |
| 228 | * @elt_init: This callback allows per-element client-defined data to |
| 229 | * be initialized when used i.e. when the element is actually |
| 230 | * claimed by tracing_map_insert() in the context of the map |
| 231 | * insertion. |
| 232 | */ |
| 233 | struct tracing_map_ops { |
| 234 | int (*elt_alloc)(struct tracing_map_elt *elt); |
Tom Zanussi | 08d43a5 | 2015-12-10 12:50:50 -0600 | [diff] [blame] | 235 | void (*elt_free)(struct tracing_map_elt *elt); |
| 236 | void (*elt_clear)(struct tracing_map_elt *elt); |
| 237 | void (*elt_init)(struct tracing_map_elt *elt); |
| 238 | }; |
| 239 | |
| 240 | extern struct tracing_map * |
| 241 | tracing_map_create(unsigned int map_bits, |
| 242 | unsigned int key_size, |
| 243 | const struct tracing_map_ops *ops, |
| 244 | void *private_data); |
| 245 | extern int tracing_map_init(struct tracing_map *map); |
| 246 | |
| 247 | extern int tracing_map_add_sum_field(struct tracing_map *map); |
Tom Zanussi | 2734b62 | 2018-01-15 20:51:46 -0600 | [diff] [blame] | 248 | extern int tracing_map_add_var(struct tracing_map *map); |
Tom Zanussi | 08d43a5 | 2015-12-10 12:50:50 -0600 | [diff] [blame] | 249 | extern int tracing_map_add_key_field(struct tracing_map *map, |
| 250 | unsigned int offset, |
| 251 | tracing_map_cmp_fn_t cmp_fn); |
| 252 | |
| 253 | extern void tracing_map_destroy(struct tracing_map *map); |
| 254 | extern void tracing_map_clear(struct tracing_map *map); |
| 255 | |
| 256 | extern struct tracing_map_elt * |
| 257 | tracing_map_insert(struct tracing_map *map, void *key); |
| 258 | extern struct tracing_map_elt * |
| 259 | tracing_map_lookup(struct tracing_map *map, void *key); |
| 260 | |
| 261 | extern tracing_map_cmp_fn_t tracing_map_cmp_num(int field_size, |
| 262 | int field_is_signed); |
| 263 | extern int tracing_map_cmp_string(void *val_a, void *val_b); |
| 264 | extern int tracing_map_cmp_none(void *val_a, void *val_b); |
| 265 | |
| 266 | extern void tracing_map_update_sum(struct tracing_map_elt *elt, |
| 267 | unsigned int i, u64 n); |
Tom Zanussi | 2734b62 | 2018-01-15 20:51:46 -0600 | [diff] [blame] | 268 | extern void tracing_map_set_var(struct tracing_map_elt *elt, |
| 269 | unsigned int i, u64 n); |
| 270 | extern bool tracing_map_var_set(struct tracing_map_elt *elt, unsigned int i); |
Tom Zanussi | 08d43a5 | 2015-12-10 12:50:50 -0600 | [diff] [blame] | 271 | extern u64 tracing_map_read_sum(struct tracing_map_elt *elt, unsigned int i); |
Tom Zanussi | 2734b62 | 2018-01-15 20:51:46 -0600 | [diff] [blame] | 272 | extern u64 tracing_map_read_var(struct tracing_map_elt *elt, unsigned int i); |
| 273 | extern u64 tracing_map_read_var_once(struct tracing_map_elt *elt, unsigned int i); |
| 274 | |
Tom Zanussi | 08d43a5 | 2015-12-10 12:50:50 -0600 | [diff] [blame] | 275 | extern void tracing_map_set_field_descr(struct tracing_map *map, |
| 276 | unsigned int i, |
| 277 | unsigned int key_offset, |
| 278 | tracing_map_cmp_fn_t cmp_fn); |
| 279 | extern int |
| 280 | tracing_map_sort_entries(struct tracing_map *map, |
| 281 | struct tracing_map_sort_key *sort_keys, |
| 282 | unsigned int n_sort_keys, |
| 283 | struct tracing_map_sort_entry ***sort_entries); |
| 284 | |
| 285 | extern void |
| 286 | tracing_map_destroy_sort_entries(struct tracing_map_sort_entry **entries, |
| 287 | unsigned int n_entries); |
| 288 | #endif /* __TRACING_MAP_H */ |