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 + get_random_u32_below(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_LRU_PRIO: Prioritize the region on its LRU lists. 90 * @DAMOS_LRU_DEPRIO: Deprioritize the region on its LRU lists. 91 * @DAMOS_STAT: Do nothing but count the stat. 92 * @NR_DAMOS_ACTIONS: Total number of DAMOS actions 93 */ 94 enum damos_action { 95 DAMOS_WILLNEED, 96 DAMOS_COLD, 97 DAMOS_PAGEOUT, 98 DAMOS_HUGEPAGE, 99 DAMOS_NOHUGEPAGE, 100 DAMOS_LRU_PRIO, 101 DAMOS_LRU_DEPRIO, 102 DAMOS_STAT, /* Do nothing but only record the stat */ 103 NR_DAMOS_ACTIONS, 104 }; 105 106 /** 107 * struct damos_quota - Controls the aggressiveness of the given scheme. 108 * @ms: Maximum milliseconds that the scheme can use. 109 * @sz: Maximum bytes of memory that the action can be applied. 110 * @reset_interval: Charge reset interval in milliseconds. 111 * 112 * @weight_sz: Weight of the region's size for prioritization. 113 * @weight_nr_accesses: Weight of the region's nr_accesses for prioritization. 114 * @weight_age: Weight of the region's age for prioritization. 115 * 116 * To avoid consuming too much CPU time or IO resources for applying the 117 * &struct damos->action to large memory, DAMON allows users to set time and/or 118 * size quotas. The quotas can be set by writing non-zero values to &ms and 119 * &sz, respectively. If the time quota is set, DAMON tries to use only up to 120 * &ms milliseconds within &reset_interval for applying the action. If the 121 * size quota is set, DAMON tries to apply the action only up to &sz bytes 122 * within &reset_interval. 123 * 124 * Internally, the time quota is transformed to a size quota using estimated 125 * throughput of the scheme's action. DAMON then compares it against &sz and 126 * uses smaller one as the effective quota. 127 * 128 * For selecting regions within the quota, DAMON prioritizes current scheme's 129 * target memory regions using the &struct damon_operations->get_scheme_score. 130 * You could customize the prioritization logic by setting &weight_sz, 131 * &weight_nr_accesses, and &weight_age, because monitoring operations are 132 * encouraged to respect those. 133 */ 134 struct damos_quota { 135 unsigned long ms; 136 unsigned long sz; 137 unsigned long reset_interval; 138 139 unsigned int weight_sz; 140 unsigned int weight_nr_accesses; 141 unsigned int weight_age; 142 143 /* private: */ 144 /* For throughput estimation */ 145 unsigned long total_charged_sz; 146 unsigned long total_charged_ns; 147 148 unsigned long esz; /* Effective size quota in bytes */ 149 150 /* For charging the quota */ 151 unsigned long charged_sz; 152 unsigned long charged_from; 153 struct damon_target *charge_target_from; 154 unsigned long charge_addr_from; 155 156 /* For prioritization */ 157 unsigned long histogram[DAMOS_MAX_SCORE + 1]; 158 unsigned int min_score; 159 }; 160 161 /** 162 * enum damos_wmark_metric - Represents the watermark metric. 163 * 164 * @DAMOS_WMARK_NONE: Ignore the watermarks of the given scheme. 165 * @DAMOS_WMARK_FREE_MEM_RATE: Free memory rate of the system in [0,1000]. 166 * @NR_DAMOS_WMARK_METRICS: Total number of DAMOS watermark metrics 167 */ 168 enum damos_wmark_metric { 169 DAMOS_WMARK_NONE, 170 DAMOS_WMARK_FREE_MEM_RATE, 171 NR_DAMOS_WMARK_METRICS, 172 }; 173 174 /** 175 * struct damos_watermarks - Controls when a given scheme should be activated. 176 * @metric: Metric for the watermarks. 177 * @interval: Watermarks check time interval in microseconds. 178 * @high: High watermark. 179 * @mid: Middle watermark. 180 * @low: Low watermark. 181 * 182 * If &metric is &DAMOS_WMARK_NONE, the scheme is always active. Being active 183 * means DAMON does monitoring and applying the action of the scheme to 184 * appropriate memory regions. Else, DAMON checks &metric of the system for at 185 * least every &interval microseconds and works as below. 186 * 187 * If &metric is higher than &high, the scheme is inactivated. If &metric is 188 * between &mid and &low, the scheme is activated. If &metric is lower than 189 * &low, the scheme is inactivated. 190 */ 191 struct damos_watermarks { 192 enum damos_wmark_metric metric; 193 unsigned long interval; 194 unsigned long high; 195 unsigned long mid; 196 unsigned long low; 197 198 /* private: */ 199 bool activated; 200 }; 201 202 /** 203 * struct damos_stat - Statistics on a given scheme. 204 * @nr_tried: Total number of regions that the scheme is tried to be applied. 205 * @sz_tried: Total size of regions that the scheme is tried to be applied. 206 * @nr_applied: Total number of regions that the scheme is applied. 207 * @sz_applied: Total size of regions that the scheme is applied. 208 * @qt_exceeds: Total number of times the quota of the scheme has exceeded. 209 */ 210 struct damos_stat { 211 unsigned long nr_tried; 212 unsigned long sz_tried; 213 unsigned long nr_applied; 214 unsigned long sz_applied; 215 unsigned long qt_exceeds; 216 }; 217 218 /** 219 * struct damos_access_pattern - Target access pattern of the given scheme. 220 * @min_sz_region: Minimum size of target regions. 221 * @max_sz_region: Maximum size of target regions. 222 * @min_nr_accesses: Minimum ``->nr_accesses`` of target regions. 223 * @max_nr_accesses: Maximum ``->nr_accesses`` of target regions. 224 * @min_age_region: Minimum age of target regions. 225 * @max_age_region: Maximum age of target regions. 226 */ 227 struct damos_access_pattern { 228 unsigned long min_sz_region; 229 unsigned long max_sz_region; 230 unsigned int min_nr_accesses; 231 unsigned int max_nr_accesses; 232 unsigned int min_age_region; 233 unsigned int max_age_region; 234 }; 235 236 /** 237 * struct damos - Represents a Data Access Monitoring-based Operation Scheme. 238 * @pattern: Access pattern of target regions. 239 * @action: &damo_action to be applied to the target regions. 240 * @quota: Control the aggressiveness of this scheme. 241 * @wmarks: Watermarks for automated (in)activation of this scheme. 242 * @stat: Statistics of this scheme. 243 * @list: List head for siblings. 244 * 245 * For each aggregation interval, DAMON finds regions which fit in the 246 * &pattern and applies &action to those. To avoid consuming too much 247 * CPU time or IO resources for the &action, "a is used. 248 * 249 * To do the work only when needed, schemes can be activated for specific 250 * system situations using &wmarks. If all schemes that registered to the 251 * monitoring context are inactive, DAMON stops monitoring either, and just 252 * repeatedly checks the watermarks. 253 * 254 * If all schemes that registered to a &struct damon_ctx are inactive, DAMON 255 * stops monitoring and just repeatedly checks the watermarks. 256 * 257 * After applying the &action to each region, &stat_count and &stat_sz is 258 * updated to reflect the number of regions and total size of regions that the 259 * &action is applied. 260 */ 261 struct damos { 262 struct damos_access_pattern pattern; 263 enum damos_action action; 264 struct damos_quota quota; 265 struct damos_watermarks wmarks; 266 struct damos_stat stat; 267 struct list_head list; 268 }; 269 270 /** 271 * enum damon_ops_id - Identifier for each monitoring operations implementation 272 * 273 * @DAMON_OPS_VADDR: Monitoring operations for virtual address spaces 274 * @DAMON_OPS_FVADDR: Monitoring operations for only fixed ranges of virtual 275 * address spaces 276 * @DAMON_OPS_PADDR: Monitoring operations for the physical address space 277 * @NR_DAMON_OPS: Number of monitoring operations implementations 278 */ 279 enum damon_ops_id { 280 DAMON_OPS_VADDR, 281 DAMON_OPS_FVADDR, 282 DAMON_OPS_PADDR, 283 NR_DAMON_OPS, 284 }; 285 286 struct damon_ctx; 287 288 /** 289 * struct damon_operations - Monitoring operations for given use cases. 290 * 291 * @id: Identifier of this operations set. 292 * @init: Initialize operations-related data structures. 293 * @update: Update operations-related data structures. 294 * @prepare_access_checks: Prepare next access check of target regions. 295 * @check_accesses: Check the accesses to target regions. 296 * @reset_aggregated: Reset aggregated accesses monitoring results. 297 * @get_scheme_score: Get the score of a region for a scheme. 298 * @apply_scheme: Apply a DAMON-based operation scheme. 299 * @target_valid: Determine if the target is valid. 300 * @cleanup: Clean up the context. 301 * 302 * DAMON can be extended for various address spaces and usages. For this, 303 * users should register the low level operations for their target address 304 * space and usecase via the &damon_ctx.ops. Then, the monitoring thread 305 * (&damon_ctx.kdamond) calls @init and @prepare_access_checks before starting 306 * the monitoring, @update after each &damon_ctx.ops_update_interval, and 307 * @check_accesses, @target_valid and @prepare_access_checks after each 308 * &damon_ctx.sample_interval. Finally, @reset_aggregated is called after each 309 * &damon_ctx.aggr_interval. 310 * 311 * Each &struct damon_operations instance having valid @id can be registered 312 * via damon_register_ops() and selected by damon_select_ops() later. 313 * @init should initialize operations-related data structures. For example, 314 * this could be used to construct proper monitoring target regions and link 315 * those to @damon_ctx.adaptive_targets. 316 * @update should update the operations-related data structures. For example, 317 * this could be used to update monitoring target regions for current status. 318 * @prepare_access_checks should manipulate the monitoring regions to be 319 * prepared for the next access check. 320 * @check_accesses should check the accesses to each region that made after the 321 * last preparation and update the number of observed accesses of each region. 322 * It should also return max number of observed accesses that made as a result 323 * of its update. The value will be used for regions adjustment threshold. 324 * @reset_aggregated should reset the access monitoring results that aggregated 325 * by @check_accesses. 326 * @get_scheme_score should return the priority score of a region for a scheme 327 * as an integer in [0, &DAMOS_MAX_SCORE]. 328 * @apply_scheme is called from @kdamond when a region for user provided 329 * DAMON-based operation scheme is found. It should apply the scheme's action 330 * to the region and return bytes of the region that the action is successfully 331 * applied. 332 * @target_valid should check whether the target is still valid for the 333 * monitoring. 334 * @cleanup is called from @kdamond just before its termination. 335 */ 336 struct damon_operations { 337 enum damon_ops_id id; 338 void (*init)(struct damon_ctx *context); 339 void (*update)(struct damon_ctx *context); 340 void (*prepare_access_checks)(struct damon_ctx *context); 341 unsigned int (*check_accesses)(struct damon_ctx *context); 342 void (*reset_aggregated)(struct damon_ctx *context); 343 int (*get_scheme_score)(struct damon_ctx *context, 344 struct damon_target *t, struct damon_region *r, 345 struct damos *scheme); 346 unsigned long (*apply_scheme)(struct damon_ctx *context, 347 struct damon_target *t, struct damon_region *r, 348 struct damos *scheme); 349 bool (*target_valid)(struct damon_target *t); 350 void (*cleanup)(struct damon_ctx *context); 351 }; 352 353 /** 354 * struct damon_callback - Monitoring events notification callbacks. 355 * 356 * @before_start: Called before starting the monitoring. 357 * @after_wmarks_check: Called after each schemes' watermarks check. 358 * @after_sampling: Called after each sampling. 359 * @after_aggregation: Called after each aggregation. 360 * @before_damos_apply: Called before applying DAMOS action. 361 * @before_terminate: Called before terminating the monitoring. 362 * @private: User private data. 363 * 364 * The monitoring thread (&damon_ctx.kdamond) calls @before_start and 365 * @before_terminate just before starting and finishing the monitoring, 366 * respectively. Therefore, those are good places for installing and cleaning 367 * @private. 368 * 369 * The monitoring thread calls @after_wmarks_check after each DAMON-based 370 * operation schemes' watermarks check. If users need to make changes to the 371 * attributes of the monitoring context while it's deactivated due to the 372 * watermarks, this is the good place to do. 373 * 374 * The monitoring thread calls @after_sampling and @after_aggregation for each 375 * of the sampling intervals and aggregation intervals, respectively. 376 * Therefore, users can safely access the monitoring results without additional 377 * protection. For the reason, users are recommended to use these callback for 378 * the accesses to the results. 379 * 380 * If any callback returns non-zero, monitoring stops. 381 */ 382 struct damon_callback { 383 void *private; 384 385 int (*before_start)(struct damon_ctx *context); 386 int (*after_wmarks_check)(struct damon_ctx *context); 387 int (*after_sampling)(struct damon_ctx *context); 388 int (*after_aggregation)(struct damon_ctx *context); 389 int (*before_damos_apply)(struct damon_ctx *context, 390 struct damon_target *target, 391 struct damon_region *region, 392 struct damos *scheme); 393 void (*before_terminate)(struct damon_ctx *context); 394 }; 395 396 /** 397 * struct damon_attrs - Monitoring attributes for accuracy/overhead control. 398 * 399 * @sample_interval: The time between access samplings. 400 * @aggr_interval: The time between monitor results aggregations. 401 * @ops_update_interval: The time between monitoring operations updates. 402 * @min_nr_regions: The minimum number of adaptive monitoring 403 * regions. 404 * @max_nr_regions: The maximum number of adaptive monitoring 405 * regions. 406 * 407 * For each @sample_interval, DAMON checks whether each region is accessed or 408 * not. It aggregates and keeps the access information (number of accesses to 409 * each region) for @aggr_interval time. DAMON also checks whether the target 410 * memory regions need update (e.g., by ``mmap()`` calls from the application, 411 * in case of virtual memory monitoring) and applies the changes for each 412 * @ops_update_interval. All time intervals are in micro-seconds. 413 * Please refer to &struct damon_operations and &struct damon_callback for more 414 * detail. 415 */ 416 struct damon_attrs { 417 unsigned long sample_interval; 418 unsigned long aggr_interval; 419 unsigned long ops_update_interval; 420 unsigned long min_nr_regions; 421 unsigned long max_nr_regions; 422 }; 423 424 /** 425 * struct damon_ctx - Represents a context for each monitoring. This is the 426 * main interface that allows users to set the attributes and get the results 427 * of the monitoring. 428 * 429 * @attrs: Monitoring attributes for accuracy/overhead control. 430 * @kdamond: Kernel thread who does the monitoring. 431 * @kdamond_lock: Mutex for the synchronizations with @kdamond. 432 * 433 * For each monitoring context, one kernel thread for the monitoring is 434 * created. The pointer to the thread is stored in @kdamond. 435 * 436 * Once started, the monitoring thread runs until explicitly required to be 437 * terminated or every monitoring target is invalid. The validity of the 438 * targets is checked via the &damon_operations.target_valid of @ops. The 439 * termination can also be explicitly requested by calling damon_stop(). 440 * The thread sets @kdamond to NULL when it terminates. Therefore, users can 441 * know whether the monitoring is ongoing or terminated by reading @kdamond. 442 * Reads and writes to @kdamond from outside of the monitoring thread must 443 * be protected by @kdamond_lock. 444 * 445 * Note that the monitoring thread protects only @kdamond via @kdamond_lock. 446 * Accesses to other fields must be protected by themselves. 447 * 448 * @ops: Set of monitoring operations for given use cases. 449 * @callback: Set of callbacks for monitoring events notifications. 450 * 451 * @adaptive_targets: Head of monitoring targets (&damon_target) list. 452 * @schemes: Head of schemes (&damos) list. 453 */ 454 struct damon_ctx { 455 struct damon_attrs attrs; 456 457 /* private: internal use only */ 458 struct timespec64 last_aggregation; 459 struct timespec64 last_ops_update; 460 461 /* public: */ 462 struct task_struct *kdamond; 463 struct mutex kdamond_lock; 464 465 struct damon_operations ops; 466 struct damon_callback callback; 467 468 struct list_head adaptive_targets; 469 struct list_head schemes; 470 }; 471 472 static inline struct damon_region *damon_next_region(struct damon_region *r) 473 { 474 return container_of(r->list.next, struct damon_region, list); 475 } 476 477 static inline struct damon_region *damon_prev_region(struct damon_region *r) 478 { 479 return container_of(r->list.prev, struct damon_region, list); 480 } 481 482 static inline struct damon_region *damon_last_region(struct damon_target *t) 483 { 484 return list_last_entry(&t->regions_list, struct damon_region, list); 485 } 486 487 static inline struct damon_region *damon_first_region(struct damon_target *t) 488 { 489 return list_first_entry(&t->regions_list, struct damon_region, list); 490 } 491 492 static inline unsigned long damon_sz_region(struct damon_region *r) 493 { 494 return r->ar.end - r->ar.start; 495 } 496 497 498 #define damon_for_each_region(r, t) \ 499 list_for_each_entry(r, &t->regions_list, list) 500 501 #define damon_for_each_region_from(r, t) \ 502 list_for_each_entry_from(r, &t->regions_list, list) 503 504 #define damon_for_each_region_safe(r, next, t) \ 505 list_for_each_entry_safe(r, next, &t->regions_list, list) 506 507 #define damon_for_each_target(t, ctx) \ 508 list_for_each_entry(t, &(ctx)->adaptive_targets, list) 509 510 #define damon_for_each_target_safe(t, next, ctx) \ 511 list_for_each_entry_safe(t, next, &(ctx)->adaptive_targets, list) 512 513 #define damon_for_each_scheme(s, ctx) \ 514 list_for_each_entry(s, &(ctx)->schemes, list) 515 516 #define damon_for_each_scheme_safe(s, next, ctx) \ 517 list_for_each_entry_safe(s, next, &(ctx)->schemes, list) 518 519 #ifdef CONFIG_DAMON 520 521 struct damon_region *damon_new_region(unsigned long start, unsigned long end); 522 523 /* 524 * Add a region between two other regions 525 */ 526 static inline void damon_insert_region(struct damon_region *r, 527 struct damon_region *prev, struct damon_region *next, 528 struct damon_target *t) 529 { 530 __list_add(&r->list, &prev->list, &next->list); 531 t->nr_regions++; 532 } 533 534 void damon_add_region(struct damon_region *r, struct damon_target *t); 535 void damon_destroy_region(struct damon_region *r, struct damon_target *t); 536 int damon_set_regions(struct damon_target *t, struct damon_addr_range *ranges, 537 unsigned int nr_ranges); 538 539 struct damos *damon_new_scheme(struct damos_access_pattern *pattern, 540 enum damos_action action, struct damos_quota *quota, 541 struct damos_watermarks *wmarks); 542 void damon_add_scheme(struct damon_ctx *ctx, struct damos *s); 543 void damon_destroy_scheme(struct damos *s); 544 545 struct damon_target *damon_new_target(void); 546 void damon_add_target(struct damon_ctx *ctx, struct damon_target *t); 547 bool damon_targets_empty(struct damon_ctx *ctx); 548 void damon_free_target(struct damon_target *t); 549 void damon_destroy_target(struct damon_target *t); 550 unsigned int damon_nr_regions(struct damon_target *t); 551 552 struct damon_ctx *damon_new_ctx(void); 553 void damon_destroy_ctx(struct damon_ctx *ctx); 554 int damon_set_attrs(struct damon_ctx *ctx, struct damon_attrs *attrs); 555 void damon_set_schemes(struct damon_ctx *ctx, 556 struct damos **schemes, ssize_t nr_schemes); 557 int damon_nr_running_ctxs(void); 558 bool damon_is_registered_ops(enum damon_ops_id id); 559 int damon_register_ops(struct damon_operations *ops); 560 int damon_select_ops(struct damon_ctx *ctx, enum damon_ops_id id); 561 562 static inline bool damon_target_has_pid(const struct damon_ctx *ctx) 563 { 564 return ctx->ops.id == DAMON_OPS_VADDR || ctx->ops.id == DAMON_OPS_FVADDR; 565 } 566 567 568 int damon_start(struct damon_ctx **ctxs, int nr_ctxs, bool exclusive); 569 int damon_stop(struct damon_ctx **ctxs, int nr_ctxs); 570 571 int damon_set_region_biggest_system_ram_default(struct damon_target *t, 572 unsigned long *start, unsigned long *end); 573 574 #endif /* CONFIG_DAMON */ 575 576 #endif /* _DAMON_H */ 577