1 /* SPDX-License-Identifier: GPL-2.0 */ 2 /* 3 * DAMON api 4 * 5 * Author: SeongJae Park <sjpark@amazon.de> 6 */ 7 8 #ifndef _DAMON_H_ 9 #define _DAMON_H_ 10 11 #include <linux/mutex.h> 12 #include <linux/time64.h> 13 #include <linux/types.h> 14 15 /* Minimal region size. Every damon_region is aligned by this. */ 16 #define DAMON_MIN_REGION PAGE_SIZE 17 18 /** 19 * struct damon_addr_range - Represents an address region of [@start, @end). 20 * @start: Start address of the region (inclusive). 21 * @end: End address of the region (exclusive). 22 */ 23 struct damon_addr_range { 24 unsigned long start; 25 unsigned long end; 26 }; 27 28 /** 29 * struct damon_region - Represents a monitoring target region. 30 * @ar: The address range of the region. 31 * @sampling_addr: Address of the sample for the next access check. 32 * @nr_accesses: Access frequency of this region. 33 * @list: List head for siblings. 34 */ 35 struct damon_region { 36 struct damon_addr_range ar; 37 unsigned long sampling_addr; 38 unsigned int nr_accesses; 39 struct list_head list; 40 }; 41 42 /** 43 * struct damon_target - Represents a monitoring target. 44 * @id: Unique identifier for this target. 45 * @nr_regions: Number of monitoring target regions of this target. 46 * @regions_list: Head of the monitoring target regions of this target. 47 * @list: List head for siblings. 48 * 49 * Each monitoring context could have multiple targets. For example, a context 50 * for virtual memory address spaces could have multiple target processes. The 51 * @id of each target should be unique among the targets of the context. For 52 * example, in the virtual address monitoring context, it could be a pidfd or 53 * an address of an mm_struct. 54 */ 55 struct damon_target { 56 unsigned long id; 57 unsigned int nr_regions; 58 struct list_head regions_list; 59 struct list_head list; 60 }; 61 62 struct damon_ctx; 63 64 /** 65 * struct damon_primitive Monitoring primitives for given use cases. 66 * 67 * @init: Initialize primitive-internal data structures. 68 * @update: Update primitive-internal data structures. 69 * @prepare_access_checks: Prepare next access check of target regions. 70 * @check_accesses: Check the accesses to target regions. 71 * @reset_aggregated: Reset aggregated accesses monitoring results. 72 * @target_valid: Determine if the target is valid. 73 * @cleanup: Clean up the context. 74 * 75 * DAMON can be extended for various address spaces and usages. For this, 76 * users should register the low level primitives for their target address 77 * space and usecase via the &damon_ctx.primitive. Then, the monitoring thread 78 * (&damon_ctx.kdamond) calls @init and @prepare_access_checks before starting 79 * the monitoring, @update after each &damon_ctx.primitive_update_interval, and 80 * @check_accesses, @target_valid and @prepare_access_checks after each 81 * &damon_ctx.sample_interval. Finally, @reset_aggregated is called after each 82 * &damon_ctx.aggr_interval. 83 * 84 * @init should initialize primitive-internal data structures. For example, 85 * this could be used to construct proper monitoring target regions and link 86 * those to @damon_ctx.adaptive_targets. 87 * @update should update the primitive-internal data structures. For example, 88 * this could be used to update monitoring target regions for current status. 89 * @prepare_access_checks should manipulate the monitoring regions to be 90 * prepared for the next access check. 91 * @check_accesses should check the accesses to each region that made after the 92 * last preparation and update the number of observed accesses of each region. 93 * It should also return max number of observed accesses that made as a result 94 * of its update. The value will be used for regions adjustment threshold. 95 * @reset_aggregated should reset the access monitoring results that aggregated 96 * by @check_accesses. 97 * @target_valid should check whether the target is still valid for the 98 * monitoring. 99 * @cleanup is called from @kdamond just before its termination. 100 */ 101 struct damon_primitive { 102 void (*init)(struct damon_ctx *context); 103 void (*update)(struct damon_ctx *context); 104 void (*prepare_access_checks)(struct damon_ctx *context); 105 unsigned int (*check_accesses)(struct damon_ctx *context); 106 void (*reset_aggregated)(struct damon_ctx *context); 107 bool (*target_valid)(void *target); 108 void (*cleanup)(struct damon_ctx *context); 109 }; 110 111 /* 112 * struct damon_callback Monitoring events notification callbacks. 113 * 114 * @before_start: Called before starting the monitoring. 115 * @after_sampling: Called after each sampling. 116 * @after_aggregation: Called after each aggregation. 117 * @before_terminate: Called before terminating the monitoring. 118 * @private: User private data. 119 * 120 * The monitoring thread (&damon_ctx.kdamond) calls @before_start and 121 * @before_terminate just before starting and finishing the monitoring, 122 * respectively. Therefore, those are good places for installing and cleaning 123 * @private. 124 * 125 * The monitoring thread calls @after_sampling and @after_aggregation for each 126 * of the sampling intervals and aggregation intervals, respectively. 127 * Therefore, users can safely access the monitoring results without additional 128 * protection. For the reason, users are recommended to use these callback for 129 * the accesses to the results. 130 * 131 * If any callback returns non-zero, monitoring stops. 132 */ 133 struct damon_callback { 134 void *private; 135 136 int (*before_start)(struct damon_ctx *context); 137 int (*after_sampling)(struct damon_ctx *context); 138 int (*after_aggregation)(struct damon_ctx *context); 139 int (*before_terminate)(struct damon_ctx *context); 140 }; 141 142 /** 143 * struct damon_ctx - Represents a context for each monitoring. This is the 144 * main interface that allows users to set the attributes and get the results 145 * of the monitoring. 146 * 147 * @sample_interval: The time between access samplings. 148 * @aggr_interval: The time between monitor results aggregations. 149 * @primitive_update_interval: The time between monitoring primitive updates. 150 * 151 * For each @sample_interval, DAMON checks whether each region is accessed or 152 * not. It aggregates and keeps the access information (number of accesses to 153 * each region) for @aggr_interval time. DAMON also checks whether the target 154 * memory regions need update (e.g., by ``mmap()`` calls from the application, 155 * in case of virtual memory monitoring) and applies the changes for each 156 * @primitive_update_interval. All time intervals are in micro-seconds. 157 * Please refer to &struct damon_primitive and &struct damon_callback for more 158 * detail. 159 * 160 * @kdamond: Kernel thread who does the monitoring. 161 * @kdamond_stop: Notifies whether kdamond should stop. 162 * @kdamond_lock: Mutex for the synchronizations with @kdamond. 163 * 164 * For each monitoring context, one kernel thread for the monitoring is 165 * created. The pointer to the thread is stored in @kdamond. 166 * 167 * Once started, the monitoring thread runs until explicitly required to be 168 * terminated or every monitoring target is invalid. The validity of the 169 * targets is checked via the &damon_primitive.target_valid of @primitive. The 170 * termination can also be explicitly requested by writing non-zero to 171 * @kdamond_stop. The thread sets @kdamond to NULL when it terminates. 172 * Therefore, users can know whether the monitoring is ongoing or terminated by 173 * reading @kdamond. Reads and writes to @kdamond and @kdamond_stop from 174 * outside of the monitoring thread must be protected by @kdamond_lock. 175 * 176 * Note that the monitoring thread protects only @kdamond and @kdamond_stop via 177 * @kdamond_lock. Accesses to other fields must be protected by themselves. 178 * 179 * @primitive: Set of monitoring primitives for given use cases. 180 * @callback: Set of callbacks for monitoring events notifications. 181 * 182 * @min_nr_regions: The minimum number of adaptive monitoring regions. 183 * @max_nr_regions: The maximum number of adaptive monitoring regions. 184 * @adaptive_targets: Head of monitoring targets (&damon_target) list. 185 */ 186 struct damon_ctx { 187 unsigned long sample_interval; 188 unsigned long aggr_interval; 189 unsigned long primitive_update_interval; 190 191 /* private: internal use only */ 192 struct timespec64 last_aggregation; 193 struct timespec64 last_primitive_update; 194 195 /* public: */ 196 struct task_struct *kdamond; 197 bool kdamond_stop; 198 struct mutex kdamond_lock; 199 200 struct damon_primitive primitive; 201 struct damon_callback callback; 202 203 unsigned long min_nr_regions; 204 unsigned long max_nr_regions; 205 struct list_head adaptive_targets; 206 }; 207 208 #define damon_next_region(r) \ 209 (container_of(r->list.next, struct damon_region, list)) 210 211 #define damon_prev_region(r) \ 212 (container_of(r->list.prev, struct damon_region, list)) 213 214 #define damon_for_each_region(r, t) \ 215 list_for_each_entry(r, &t->regions_list, list) 216 217 #define damon_for_each_region_safe(r, next, t) \ 218 list_for_each_entry_safe(r, next, &t->regions_list, list) 219 220 #define damon_for_each_target(t, ctx) \ 221 list_for_each_entry(t, &(ctx)->adaptive_targets, list) 222 223 #define damon_for_each_target_safe(t, next, ctx) \ 224 list_for_each_entry_safe(t, next, &(ctx)->adaptive_targets, list) 225 226 #ifdef CONFIG_DAMON 227 228 struct damon_region *damon_new_region(unsigned long start, unsigned long end); 229 inline void damon_insert_region(struct damon_region *r, 230 struct damon_region *prev, struct damon_region *next, 231 struct damon_target *t); 232 void damon_add_region(struct damon_region *r, struct damon_target *t); 233 void damon_destroy_region(struct damon_region *r, struct damon_target *t); 234 235 struct damon_target *damon_new_target(unsigned long id); 236 void damon_add_target(struct damon_ctx *ctx, struct damon_target *t); 237 void damon_free_target(struct damon_target *t); 238 void damon_destroy_target(struct damon_target *t); 239 unsigned int damon_nr_regions(struct damon_target *t); 240 241 struct damon_ctx *damon_new_ctx(void); 242 void damon_destroy_ctx(struct damon_ctx *ctx); 243 int damon_set_targets(struct damon_ctx *ctx, 244 unsigned long *ids, ssize_t nr_ids); 245 int damon_set_attrs(struct damon_ctx *ctx, unsigned long sample_int, 246 unsigned long aggr_int, unsigned long primitive_upd_int, 247 unsigned long min_nr_reg, unsigned long max_nr_reg); 248 int damon_nr_running_ctxs(void); 249 250 int damon_start(struct damon_ctx **ctxs, int nr_ctxs); 251 int damon_stop(struct damon_ctx **ctxs, int nr_ctxs); 252 253 #endif /* CONFIG_DAMON */ 254 255 #ifdef CONFIG_DAMON_VADDR 256 257 /* Monitoring primitives for virtual memory address spaces */ 258 void damon_va_init(struct damon_ctx *ctx); 259 void damon_va_update(struct damon_ctx *ctx); 260 void damon_va_prepare_access_checks(struct damon_ctx *ctx); 261 unsigned int damon_va_check_accesses(struct damon_ctx *ctx); 262 bool damon_va_target_valid(void *t); 263 void damon_va_cleanup(struct damon_ctx *ctx); 264 void damon_va_set_primitives(struct damon_ctx *ctx); 265 266 #endif /* CONFIG_DAMON_VADDR */ 267 268 #endif /* _DAMON_H */ 269