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 #include <linux/random.h> 15 16 /* Minimal region size. Every damon_region is aligned by this. */ 17 #define DAMON_MIN_REGION PAGE_SIZE 18 /* Max priority score for DAMON-based operation schemes */ 19 #define DAMOS_MAX_SCORE (99) 20 21 /* Get a random number in [l, r) */ 22 static inline unsigned long damon_rand(unsigned long l, unsigned long r) 23 { 24 return l + prandom_u32_max(r - l); 25 } 26 27 /** 28 * struct damon_addr_range - Represents an address region of [@start, @end). 29 * @start: Start address of the region (inclusive). 30 * @end: End address of the region (exclusive). 31 */ 32 struct damon_addr_range { 33 unsigned long start; 34 unsigned long end; 35 }; 36 37 /** 38 * struct damon_region - Represents a monitoring target region. 39 * @ar: The address range of the region. 40 * @sampling_addr: Address of the sample for the next access check. 41 * @nr_accesses: Access frequency of this region. 42 * @list: List head for siblings. 43 * @age: Age of this region. 44 * 45 * @age is initially zero, increased for each aggregation interval, and reset 46 * to zero again if the access frequency is significantly changed. If two 47 * regions are merged into a new region, both @nr_accesses and @age of the new 48 * region are set as region size-weighted average of those of the two regions. 49 */ 50 struct damon_region { 51 struct damon_addr_range ar; 52 unsigned long sampling_addr; 53 unsigned int nr_accesses; 54 struct list_head list; 55 56 unsigned int age; 57 /* private: Internal value for age calculation. */ 58 unsigned int last_nr_accesses; 59 }; 60 61 /** 62 * struct damon_target - Represents a monitoring target. 63 * @pid: The PID of the virtual address space to monitor. 64 * @nr_regions: Number of monitoring target regions of this target. 65 * @regions_list: Head of the monitoring target regions of this target. 66 * @list: List head for siblings. 67 * 68 * Each monitoring context could have multiple targets. For example, a context 69 * for virtual memory address spaces could have multiple target processes. The 70 * @pid should be set for appropriate &struct damon_operations including the 71 * virtual address spaces monitoring operations. 72 */ 73 struct damon_target { 74 struct pid *pid; 75 unsigned int nr_regions; 76 struct list_head regions_list; 77 struct list_head list; 78 }; 79 80 /** 81 * enum damos_action - Represents an action of a Data Access Monitoring-based 82 * Operation Scheme. 83 * 84 * @DAMOS_WILLNEED: Call ``madvise()`` for the region with MADV_WILLNEED. 85 * @DAMOS_COLD: Call ``madvise()`` for the region with MADV_COLD. 86 * @DAMOS_PAGEOUT: Call ``madvise()`` for the region with MADV_PAGEOUT. 87 * @DAMOS_HUGEPAGE: Call ``madvise()`` for the region with MADV_HUGEPAGE. 88 * @DAMOS_NOHUGEPAGE: Call ``madvise()`` for the region with MADV_NOHUGEPAGE. 89 * @DAMOS_STAT: Do nothing but count the stat. 90 * @NR_DAMOS_ACTIONS: Total number of DAMOS actions 91 */ 92 enum damos_action { 93 DAMOS_WILLNEED, 94 DAMOS_COLD, 95 DAMOS_PAGEOUT, 96 DAMOS_HUGEPAGE, 97 DAMOS_NOHUGEPAGE, 98 DAMOS_STAT, /* Do nothing but only record the stat */ 99 NR_DAMOS_ACTIONS, 100 }; 101 102 /** 103 * struct damos_quota - Controls the aggressiveness of the given scheme. 104 * @ms: Maximum milliseconds that the scheme can use. 105 * @sz: Maximum bytes of memory that the action can be applied. 106 * @reset_interval: Charge reset interval in milliseconds. 107 * 108 * @weight_sz: Weight of the region's size for prioritization. 109 * @weight_nr_accesses: Weight of the region's nr_accesses for prioritization. 110 * @weight_age: Weight of the region's age for prioritization. 111 * 112 * To avoid consuming too much CPU time or IO resources for applying the 113 * &struct damos->action to large memory, DAMON allows users to set time and/or 114 * size quotas. The quotas can be set by writing non-zero values to &ms and 115 * &sz, respectively. If the time quota is set, DAMON tries to use only up to 116 * &ms milliseconds within &reset_interval for applying the action. If the 117 * size quota is set, DAMON tries to apply the action only up to &sz bytes 118 * within &reset_interval. 119 * 120 * Internally, the time quota is transformed to a size quota using estimated 121 * throughput of the scheme's action. DAMON then compares it against &sz and 122 * uses smaller one as the effective quota. 123 * 124 * For selecting regions within the quota, DAMON prioritizes current scheme's 125 * target memory regions using the &struct damon_operations->get_scheme_score. 126 * You could customize the prioritization logic by setting &weight_sz, 127 * &weight_nr_accesses, and &weight_age, because monitoring operations are 128 * encouraged to respect those. 129 */ 130 struct damos_quota { 131 unsigned long ms; 132 unsigned long sz; 133 unsigned long reset_interval; 134 135 unsigned int weight_sz; 136 unsigned int weight_nr_accesses; 137 unsigned int weight_age; 138 139 /* private: */ 140 /* For throughput estimation */ 141 unsigned long total_charged_sz; 142 unsigned long total_charged_ns; 143 144 unsigned long esz; /* Effective size quota in bytes */ 145 146 /* For charging the quota */ 147 unsigned long charged_sz; 148 unsigned long charged_from; 149 struct damon_target *charge_target_from; 150 unsigned long charge_addr_from; 151 152 /* For prioritization */ 153 unsigned long histogram[DAMOS_MAX_SCORE + 1]; 154 unsigned int min_score; 155 }; 156 157 /** 158 * enum damos_wmark_metric - Represents the watermark metric. 159 * 160 * @DAMOS_WMARK_NONE: Ignore the watermarks of the given scheme. 161 * @DAMOS_WMARK_FREE_MEM_RATE: Free memory rate of the system in [0,1000]. 162 * @NR_DAMOS_WMARK_METRICS: Total number of DAMOS watermark metrics 163 */ 164 enum damos_wmark_metric { 165 DAMOS_WMARK_NONE, 166 DAMOS_WMARK_FREE_MEM_RATE, 167 NR_DAMOS_WMARK_METRICS, 168 }; 169 170 /** 171 * struct damos_watermarks - Controls when a given scheme should be activated. 172 * @metric: Metric for the watermarks. 173 * @interval: Watermarks check time interval in microseconds. 174 * @high: High watermark. 175 * @mid: Middle watermark. 176 * @low: Low watermark. 177 * 178 * If &metric is &DAMOS_WMARK_NONE, the scheme is always active. Being active 179 * means DAMON does monitoring and applying the action of the scheme to 180 * appropriate memory regions. Else, DAMON checks &metric of the system for at 181 * least every &interval microseconds and works as below. 182 * 183 * If &metric is higher than &high, the scheme is inactivated. If &metric is 184 * between &mid and &low, the scheme is activated. If &metric is lower than 185 * &low, the scheme is inactivated. 186 */ 187 struct damos_watermarks { 188 enum damos_wmark_metric metric; 189 unsigned long interval; 190 unsigned long high; 191 unsigned long mid; 192 unsigned long low; 193 194 /* private: */ 195 bool activated; 196 }; 197 198 /** 199 * struct damos_stat - Statistics on a given scheme. 200 * @nr_tried: Total number of regions that the scheme is tried to be applied. 201 * @sz_tried: Total size of regions that the scheme is tried to be applied. 202 * @nr_applied: Total number of regions that the scheme is applied. 203 * @sz_applied: Total size of regions that the scheme is applied. 204 * @qt_exceeds: Total number of times the quota of the scheme has exceeded. 205 */ 206 struct damos_stat { 207 unsigned long nr_tried; 208 unsigned long sz_tried; 209 unsigned long nr_applied; 210 unsigned long sz_applied; 211 unsigned long qt_exceeds; 212 }; 213 214 /** 215 * struct damos - Represents a Data Access Monitoring-based Operation Scheme. 216 * @min_sz_region: Minimum size of target regions. 217 * @max_sz_region: Maximum size of target regions. 218 * @min_nr_accesses: Minimum ``->nr_accesses`` of target regions. 219 * @max_nr_accesses: Maximum ``->nr_accesses`` of target regions. 220 * @min_age_region: Minimum age of target regions. 221 * @max_age_region: Maximum age of target regions. 222 * @action: &damo_action to be applied to the target regions. 223 * @quota: Control the aggressiveness of this scheme. 224 * @wmarks: Watermarks for automated (in)activation of this scheme. 225 * @stat: Statistics of this scheme. 226 * @list: List head for siblings. 227 * 228 * For each aggregation interval, DAMON finds regions which fit in the 229 * condition (&min_sz_region, &max_sz_region, &min_nr_accesses, 230 * &max_nr_accesses, &min_age_region, &max_age_region) and applies &action to 231 * those. To avoid consuming too much CPU time or IO resources for the 232 * &action, "a is used. 233 * 234 * To do the work only when needed, schemes can be activated for specific 235 * system situations using &wmarks. If all schemes that registered to the 236 * monitoring context are inactive, DAMON stops monitoring either, and just 237 * repeatedly checks the watermarks. 238 * 239 * If all schemes that registered to a &struct damon_ctx are inactive, DAMON 240 * stops monitoring and just repeatedly checks the watermarks. 241 * 242 * After applying the &action to each region, &stat_count and &stat_sz is 243 * updated to reflect the number of regions and total size of regions that the 244 * &action is applied. 245 */ 246 struct damos { 247 unsigned long min_sz_region; 248 unsigned long max_sz_region; 249 unsigned int min_nr_accesses; 250 unsigned int max_nr_accesses; 251 unsigned int min_age_region; 252 unsigned int max_age_region; 253 enum damos_action action; 254 struct damos_quota quota; 255 struct damos_watermarks wmarks; 256 struct damos_stat stat; 257 struct list_head list; 258 }; 259 260 /** 261 * enum damon_ops_id - Identifier for each monitoring operations implementation 262 * 263 * @DAMON_OPS_VADDR: Monitoring operations for virtual address spaces 264 * @DAMON_OPS_FVADDR: Monitoring operations for only fixed ranges of virtual 265 * address spaces 266 * @DAMON_OPS_PADDR: Monitoring operations for the physical address space 267 * @NR_DAMON_OPS: Number of monitoring operations implementations 268 */ 269 enum damon_ops_id { 270 DAMON_OPS_VADDR, 271 DAMON_OPS_FVADDR, 272 DAMON_OPS_PADDR, 273 NR_DAMON_OPS, 274 }; 275 276 struct damon_ctx; 277 278 /** 279 * struct damon_operations - Monitoring operations for given use cases. 280 * 281 * @id: Identifier of this operations set. 282 * @init: Initialize operations-related data structures. 283 * @update: Update operations-related data structures. 284 * @prepare_access_checks: Prepare next access check of target regions. 285 * @check_accesses: Check the accesses to target regions. 286 * @reset_aggregated: Reset aggregated accesses monitoring results. 287 * @get_scheme_score: Get the score of a region for a scheme. 288 * @apply_scheme: Apply a DAMON-based operation scheme. 289 * @target_valid: Determine if the target is valid. 290 * @cleanup: Clean up the context. 291 * 292 * DAMON can be extended for various address spaces and usages. For this, 293 * users should register the low level operations for their target address 294 * space and usecase via the &damon_ctx.ops. Then, the monitoring thread 295 * (&damon_ctx.kdamond) calls @init and @prepare_access_checks before starting 296 * the monitoring, @update after each &damon_ctx.ops_update_interval, and 297 * @check_accesses, @target_valid and @prepare_access_checks after each 298 * &damon_ctx.sample_interval. Finally, @reset_aggregated is called after each 299 * &damon_ctx.aggr_interval. 300 * 301 * Each &struct damon_operations instance having valid @id can be registered 302 * via damon_register_ops() and selected by damon_select_ops() later. 303 * @init should initialize operations-related data structures. For example, 304 * this could be used to construct proper monitoring target regions and link 305 * those to @damon_ctx.adaptive_targets. 306 * @update should update the operations-related data structures. For example, 307 * this could be used to update monitoring target regions for current status. 308 * @prepare_access_checks should manipulate the monitoring regions to be 309 * prepared for the next access check. 310 * @check_accesses should check the accesses to each region that made after the 311 * last preparation and update the number of observed accesses of each region. 312 * It should also return max number of observed accesses that made as a result 313 * of its update. The value will be used for regions adjustment threshold. 314 * @reset_aggregated should reset the access monitoring results that aggregated 315 * by @check_accesses. 316 * @get_scheme_score should return the priority score of a region for a scheme 317 * as an integer in [0, &DAMOS_MAX_SCORE]. 318 * @apply_scheme is called from @kdamond when a region for user provided 319 * DAMON-based operation scheme is found. It should apply the scheme's action 320 * to the region and return bytes of the region that the action is successfully 321 * applied. 322 * @target_valid should check whether the target is still valid for the 323 * monitoring. 324 * @cleanup is called from @kdamond just before its termination. 325 */ 326 struct damon_operations { 327 enum damon_ops_id id; 328 void (*init)(struct damon_ctx *context); 329 void (*update)(struct damon_ctx *context); 330 void (*prepare_access_checks)(struct damon_ctx *context); 331 unsigned int (*check_accesses)(struct damon_ctx *context); 332 void (*reset_aggregated)(struct damon_ctx *context); 333 int (*get_scheme_score)(struct damon_ctx *context, 334 struct damon_target *t, struct damon_region *r, 335 struct damos *scheme); 336 unsigned long (*apply_scheme)(struct damon_ctx *context, 337 struct damon_target *t, struct damon_region *r, 338 struct damos *scheme); 339 bool (*target_valid)(void *target); 340 void (*cleanup)(struct damon_ctx *context); 341 }; 342 343 /** 344 * struct damon_callback - Monitoring events notification callbacks. 345 * 346 * @before_start: Called before starting the monitoring. 347 * @after_wmarks_check: Called after each schemes' watermarks check. 348 * @after_sampling: Called after each sampling. 349 * @after_aggregation: Called after each aggregation. 350 * @before_terminate: Called before terminating the monitoring. 351 * @private: User private data. 352 * 353 * The monitoring thread (&damon_ctx.kdamond) calls @before_start and 354 * @before_terminate just before starting and finishing the monitoring, 355 * respectively. Therefore, those are good places for installing and cleaning 356 * @private. 357 * 358 * The monitoring thread calls @after_wmarks_check after each DAMON-based 359 * operation schemes' watermarks check. If users need to make changes to the 360 * attributes of the monitoring context while it's deactivated due to the 361 * watermarks, this is the good place to do. 362 * 363 * The monitoring thread calls @after_sampling and @after_aggregation for each 364 * of the sampling intervals and aggregation intervals, respectively. 365 * Therefore, users can safely access the monitoring results without additional 366 * protection. For the reason, users are recommended to use these callback for 367 * the accesses to the results. 368 * 369 * If any callback returns non-zero, monitoring stops. 370 */ 371 struct damon_callback { 372 void *private; 373 374 int (*before_start)(struct damon_ctx *context); 375 int (*after_wmarks_check)(struct damon_ctx *context); 376 int (*after_sampling)(struct damon_ctx *context); 377 int (*after_aggregation)(struct damon_ctx *context); 378 void (*before_terminate)(struct damon_ctx *context); 379 }; 380 381 /** 382 * struct damon_ctx - Represents a context for each monitoring. This is the 383 * main interface that allows users to set the attributes and get the results 384 * of the monitoring. 385 * 386 * @sample_interval: The time between access samplings. 387 * @aggr_interval: The time between monitor results aggregations. 388 * @ops_update_interval: The time between monitoring operations updates. 389 * 390 * For each @sample_interval, DAMON checks whether each region is accessed or 391 * not. It aggregates and keeps the access information (number of accesses to 392 * each region) for @aggr_interval time. DAMON also checks whether the target 393 * memory regions need update (e.g., by ``mmap()`` calls from the application, 394 * in case of virtual memory monitoring) and applies the changes for each 395 * @ops_update_interval. All time intervals are in micro-seconds. 396 * Please refer to &struct damon_operations and &struct damon_callback for more 397 * detail. 398 * 399 * @kdamond: Kernel thread who does the monitoring. 400 * @kdamond_stop: Notifies whether kdamond should stop. 401 * @kdamond_lock: Mutex for the synchronizations with @kdamond. 402 * 403 * For each monitoring context, one kernel thread for the monitoring is 404 * created. The pointer to the thread is stored in @kdamond. 405 * 406 * Once started, the monitoring thread runs until explicitly required to be 407 * terminated or every monitoring target is invalid. The validity of the 408 * targets is checked via the &damon_operations.target_valid of @ops. The 409 * termination can also be explicitly requested by writing non-zero to 410 * @kdamond_stop. The thread sets @kdamond to NULL when it terminates. 411 * Therefore, users can know whether the monitoring is ongoing or terminated by 412 * reading @kdamond. Reads and writes to @kdamond and @kdamond_stop from 413 * outside of the monitoring thread must be protected by @kdamond_lock. 414 * 415 * Note that the monitoring thread protects only @kdamond and @kdamond_stop via 416 * @kdamond_lock. Accesses to other fields must be protected by themselves. 417 * 418 * @ops: Set of monitoring operations for given use cases. 419 * @callback: Set of callbacks for monitoring events notifications. 420 * 421 * @min_nr_regions: The minimum number of adaptive monitoring regions. 422 * @max_nr_regions: The maximum number of adaptive monitoring regions. 423 * @adaptive_targets: Head of monitoring targets (&damon_target) list. 424 * @schemes: Head of schemes (&damos) list. 425 */ 426 struct damon_ctx { 427 unsigned long sample_interval; 428 unsigned long aggr_interval; 429 unsigned long ops_update_interval; 430 431 /* private: internal use only */ 432 struct timespec64 last_aggregation; 433 struct timespec64 last_ops_update; 434 435 /* public: */ 436 struct task_struct *kdamond; 437 struct mutex kdamond_lock; 438 439 struct damon_operations ops; 440 struct damon_callback callback; 441 442 unsigned long min_nr_regions; 443 unsigned long max_nr_regions; 444 struct list_head adaptive_targets; 445 struct list_head schemes; 446 }; 447 448 static inline struct damon_region *damon_next_region(struct damon_region *r) 449 { 450 return container_of(r->list.next, struct damon_region, list); 451 } 452 453 static inline struct damon_region *damon_prev_region(struct damon_region *r) 454 { 455 return container_of(r->list.prev, struct damon_region, list); 456 } 457 458 static inline struct damon_region *damon_last_region(struct damon_target *t) 459 { 460 return list_last_entry(&t->regions_list, struct damon_region, list); 461 } 462 463 #define damon_for_each_region(r, t) \ 464 list_for_each_entry(r, &t->regions_list, list) 465 466 #define damon_for_each_region_safe(r, next, t) \ 467 list_for_each_entry_safe(r, next, &t->regions_list, list) 468 469 #define damon_for_each_target(t, ctx) \ 470 list_for_each_entry(t, &(ctx)->adaptive_targets, list) 471 472 #define damon_for_each_target_safe(t, next, ctx) \ 473 list_for_each_entry_safe(t, next, &(ctx)->adaptive_targets, list) 474 475 #define damon_for_each_scheme(s, ctx) \ 476 list_for_each_entry(s, &(ctx)->schemes, list) 477 478 #define damon_for_each_scheme_safe(s, next, ctx) \ 479 list_for_each_entry_safe(s, next, &(ctx)->schemes, list) 480 481 #ifdef CONFIG_DAMON 482 483 struct damon_region *damon_new_region(unsigned long start, unsigned long end); 484 485 /* 486 * Add a region between two other regions 487 */ 488 static inline void damon_insert_region(struct damon_region *r, 489 struct damon_region *prev, struct damon_region *next, 490 struct damon_target *t) 491 { 492 __list_add(&r->list, &prev->list, &next->list); 493 t->nr_regions++; 494 } 495 496 void damon_add_region(struct damon_region *r, struct damon_target *t); 497 void damon_destroy_region(struct damon_region *r, struct damon_target *t); 498 int damon_set_regions(struct damon_target *t, struct damon_addr_range *ranges, 499 unsigned int nr_ranges); 500 501 struct damos *damon_new_scheme( 502 unsigned long min_sz_region, unsigned long max_sz_region, 503 unsigned int min_nr_accesses, unsigned int max_nr_accesses, 504 unsigned int min_age_region, unsigned int max_age_region, 505 enum damos_action action, struct damos_quota *quota, 506 struct damos_watermarks *wmarks); 507 void damon_add_scheme(struct damon_ctx *ctx, struct damos *s); 508 void damon_destroy_scheme(struct damos *s); 509 510 struct damon_target *damon_new_target(void); 511 void damon_add_target(struct damon_ctx *ctx, struct damon_target *t); 512 bool damon_targets_empty(struct damon_ctx *ctx); 513 void damon_free_target(struct damon_target *t); 514 void damon_destroy_target(struct damon_target *t); 515 unsigned int damon_nr_regions(struct damon_target *t); 516 517 struct damon_ctx *damon_new_ctx(void); 518 void damon_destroy_ctx(struct damon_ctx *ctx); 519 int damon_set_attrs(struct damon_ctx *ctx, unsigned long sample_int, 520 unsigned long aggr_int, unsigned long ops_upd_int, 521 unsigned long min_nr_reg, unsigned long max_nr_reg); 522 int damon_set_schemes(struct damon_ctx *ctx, 523 struct damos **schemes, ssize_t nr_schemes); 524 int damon_nr_running_ctxs(void); 525 bool damon_is_registered_ops(enum damon_ops_id id); 526 int damon_register_ops(struct damon_operations *ops); 527 int damon_select_ops(struct damon_ctx *ctx, enum damon_ops_id id); 528 529 int damon_start(struct damon_ctx **ctxs, int nr_ctxs, bool exclusive); 530 int damon_stop(struct damon_ctx **ctxs, int nr_ctxs); 531 532 #endif /* CONFIG_DAMON */ 533 534 #endif /* _DAMON_H */ 535