/* SPDX-License-Identifier: GPL-2.0 */ /* * DAMON api * * Author: SeongJae Park */ #ifndef _DAMON_H_ #define _DAMON_H_ #include #include #include /* Minimal region size. Every damon_region is aligned by this. */ #define DAMON_MIN_REGION PAGE_SIZE /* Max priority score for DAMON-based operation schemes */ #define DAMOS_MAX_SCORE (99) /** * struct damon_addr_range - Represents an address region of [@start, @end). * @start: Start address of the region (inclusive). * @end: End address of the region (exclusive). */ struct damon_addr_range { unsigned long start; unsigned long end; }; /** * struct damon_region - Represents a monitoring target region. * @ar: The address range of the region. * @sampling_addr: Address of the sample for the next access check. * @nr_accesses: Access frequency of this region. * @list: List head for siblings. * @age: Age of this region. * * @age is initially zero, increased for each aggregation interval, and reset * to zero again if the access frequency is significantly changed. If two * regions are merged into a new region, both @nr_accesses and @age of the new * region are set as region size-weighted average of those of the two regions. */ struct damon_region { struct damon_addr_range ar; unsigned long sampling_addr; unsigned int nr_accesses; struct list_head list; unsigned int age; /* private: Internal value for age calculation. */ unsigned int last_nr_accesses; }; /** * struct damon_target - Represents a monitoring target. * @id: Unique identifier for this target. * @nr_regions: Number of monitoring target regions of this target. * @regions_list: Head of the monitoring target regions of this target. * @list: List head for siblings. * * Each monitoring context could have multiple targets. For example, a context * for virtual memory address spaces could have multiple target processes. The * @id of each target should be unique among the targets of the context. For * example, in the virtual address monitoring context, it could be a pidfd or * an address of an mm_struct. */ struct damon_target { unsigned long id; unsigned int nr_regions; struct list_head regions_list; struct list_head list; }; /** * enum damos_action - Represents an action of a Data Access Monitoring-based * Operation Scheme. * * @DAMOS_WILLNEED: Call ``madvise()`` for the region with MADV_WILLNEED. * @DAMOS_COLD: Call ``madvise()`` for the region with MADV_COLD. * @DAMOS_PAGEOUT: Call ``madvise()`` for the region with MADV_PAGEOUT. * @DAMOS_HUGEPAGE: Call ``madvise()`` for the region with MADV_HUGEPAGE. * @DAMOS_NOHUGEPAGE: Call ``madvise()`` for the region with MADV_NOHUGEPAGE. * @DAMOS_STAT: Do nothing but count the stat. */ enum damos_action { DAMOS_WILLNEED, DAMOS_COLD, DAMOS_PAGEOUT, DAMOS_HUGEPAGE, DAMOS_NOHUGEPAGE, DAMOS_STAT, /* Do nothing but only record the stat */ }; /** * struct damos_quota - Controls the aggressiveness of the given scheme. * @ms: Maximum milliseconds that the scheme can use. * @sz: Maximum bytes of memory that the action can be applied. * @reset_interval: Charge reset interval in milliseconds. * * @weight_sz: Weight of the region's size for prioritization. * @weight_nr_accesses: Weight of the region's nr_accesses for prioritization. * @weight_age: Weight of the region's age for prioritization. * * To avoid consuming too much CPU time or IO resources for applying the * &struct damos->action to large memory, DAMON allows users to set time and/or * size quotas. The quotas can be set by writing non-zero values to &ms and * &sz, respectively. If the time quota is set, DAMON tries to use only up to * &ms milliseconds within &reset_interval for applying the action. If the * size quota is set, DAMON tries to apply the action only up to &sz bytes * within &reset_interval. * * Internally, the time quota is transformed to a size quota using estimated * throughput of the scheme's action. DAMON then compares it against &sz and * uses smaller one as the effective quota. * * For selecting regions within the quota, DAMON prioritizes current scheme's * target memory regions using the &struct damon_primitive->get_scheme_score. * You could customize the prioritization logic by setting &weight_sz, * &weight_nr_accesses, and &weight_age, because monitoring primitives are * encouraged to respect those. */ struct damos_quota { unsigned long ms; unsigned long sz; unsigned long reset_interval; unsigned int weight_sz; unsigned int weight_nr_accesses; unsigned int weight_age; /* private: */ /* For throughput estimation */ unsigned long total_charged_sz; unsigned long total_charged_ns; unsigned long esz; /* Effective size quota in bytes */ /* For charging the quota */ unsigned long charged_sz; unsigned long charged_from; struct damon_target *charge_target_from; unsigned long charge_addr_from; /* For prioritization */ unsigned long histogram[DAMOS_MAX_SCORE + 1]; unsigned int min_score; }; /** * enum damos_wmark_metric - Represents the watermark metric. * * @DAMOS_WMARK_NONE: Ignore the watermarks of the given scheme. * @DAMOS_WMARK_FREE_MEM_RATE: Free memory rate of the system in [0,1000]. */ enum damos_wmark_metric { DAMOS_WMARK_NONE, DAMOS_WMARK_FREE_MEM_RATE, }; /** * struct damos_watermarks - Controls when a given scheme should be activated. * @metric: Metric for the watermarks. * @interval: Watermarks check time interval in microseconds. * @high: High watermark. * @mid: Middle watermark. * @low: Low watermark. * * If &metric is &DAMOS_WMARK_NONE, the scheme is always active. Being active * means DAMON does monitoring and applying the action of the scheme to * appropriate memory regions. Else, DAMON checks &metric of the system for at * least every &interval microseconds and works as below. * * If &metric is higher than &high, the scheme is inactivated. If &metric is * between &mid and &low, the scheme is activated. If &metric is lower than * &low, the scheme is inactivated. */ struct damos_watermarks { enum damos_wmark_metric metric; unsigned long interval; unsigned long high; unsigned long mid; unsigned long low; /* private: */ bool activated; }; /** * struct damos - Represents a Data Access Monitoring-based Operation Scheme. * @min_sz_region: Minimum size of target regions. * @max_sz_region: Maximum size of target regions. * @min_nr_accesses: Minimum ``->nr_accesses`` of target regions. * @max_nr_accesses: Maximum ``->nr_accesses`` of target regions. * @min_age_region: Minimum age of target regions. * @max_age_region: Maximum age of target regions. * @action: &damo_action to be applied to the target regions. * @quota: Control the aggressiveness of this scheme. * @wmarks: Watermarks for automated (in)activation of this scheme. * @stat_count: Total number of regions that this scheme is applied. * @stat_sz: Total size of regions that this scheme is applied. * @list: List head for siblings. * * For each aggregation interval, DAMON finds regions which fit in the * condition (&min_sz_region, &max_sz_region, &min_nr_accesses, * &max_nr_accesses, &min_age_region, &max_age_region) and applies &action to * those. To avoid consuming too much CPU time or IO resources for the * &action, "a is used. * * To do the work only when needed, schemes can be activated for specific * system situations using &wmarks. If all schemes that registered to the * monitoring context are inactive, DAMON stops monitoring either, and just * repeatedly checks the watermarks. * * If all schemes that registered to a &struct damon_ctx are inactive, DAMON * stops monitoring and just repeatedly checks the watermarks. * * After applying the &action to each region, &stat_count and &stat_sz is * updated to reflect the number of regions and total size of regions that the * &action is applied. */ struct damos { unsigned long min_sz_region; unsigned long max_sz_region; unsigned int min_nr_accesses; unsigned int max_nr_accesses; unsigned int min_age_region; unsigned int max_age_region; enum damos_action action; struct damos_quota quota; struct damos_watermarks wmarks; unsigned long stat_count; unsigned long stat_sz; struct list_head list; }; struct damon_ctx; /** * struct damon_primitive - Monitoring primitives for given use cases. * * @init: Initialize primitive-internal data structures. * @update: Update primitive-internal data structures. * @prepare_access_checks: Prepare next access check of target regions. * @check_accesses: Check the accesses to target regions. * @reset_aggregated: Reset aggregated accesses monitoring results. * @get_scheme_score: Get the score of a region for a scheme. * @apply_scheme: Apply a DAMON-based operation scheme. * @target_valid: Determine if the target is valid. * @cleanup: Clean up the context. * * DAMON can be extended for various address spaces and usages. For this, * users should register the low level primitives for their target address * space and usecase via the &damon_ctx.primitive. Then, the monitoring thread * (&damon_ctx.kdamond) calls @init and @prepare_access_checks before starting * the monitoring, @update after each &damon_ctx.primitive_update_interval, and * @check_accesses, @target_valid and @prepare_access_checks after each * &damon_ctx.sample_interval. Finally, @reset_aggregated is called after each * &damon_ctx.aggr_interval. * * @init should initialize primitive-internal data structures. For example, * this could be used to construct proper monitoring target regions and link * those to @damon_ctx.adaptive_targets. * @update should update the primitive-internal data structures. For example, * this could be used to update monitoring target regions for current status. * @prepare_access_checks should manipulate the monitoring regions to be * prepared for the next access check. * @check_accesses should check the accesses to each region that made after the * last preparation and update the number of observed accesses of each region. * It should also return max number of observed accesses that made as a result * of its update. The value will be used for regions adjustment threshold. * @reset_aggregated should reset the access monitoring results that aggregated * by @check_accesses. * @get_scheme_score should return the priority score of a region for a scheme * as an integer in [0, &DAMOS_MAX_SCORE]. * @apply_scheme is called from @kdamond when a region for user provided * DAMON-based operation scheme is found. It should apply the scheme's action * to the region. This is not used for &DAMON_ARBITRARY_TARGET case. * @target_valid should check whether the target is still valid for the * monitoring. * @cleanup is called from @kdamond just before its termination. */ struct damon_primitive { void (*init)(struct damon_ctx *context); void (*update)(struct damon_ctx *context); void (*prepare_access_checks)(struct damon_ctx *context); unsigned int (*check_accesses)(struct damon_ctx *context); void (*reset_aggregated)(struct damon_ctx *context); int (*get_scheme_score)(struct damon_ctx *context, struct damon_target *t, struct damon_region *r, struct damos *scheme); int (*apply_scheme)(struct damon_ctx *context, struct damon_target *t, struct damon_region *r, struct damos *scheme); bool (*target_valid)(void *target); void (*cleanup)(struct damon_ctx *context); }; /** * struct damon_callback - Monitoring events notification callbacks. * * @before_start: Called before starting the monitoring. * @after_sampling: Called after each sampling. * @after_aggregation: Called after each aggregation. * @before_terminate: Called before terminating the monitoring. * @private: User private data. * * The monitoring thread (&damon_ctx.kdamond) calls @before_start and * @before_terminate just before starting and finishing the monitoring, * respectively. Therefore, those are good places for installing and cleaning * @private. * * The monitoring thread calls @after_sampling and @after_aggregation for each * of the sampling intervals and aggregation intervals, respectively. * Therefore, users can safely access the monitoring results without additional * protection. For the reason, users are recommended to use these callback for * the accesses to the results. * * If any callback returns non-zero, monitoring stops. */ struct damon_callback { void *private; int (*before_start)(struct damon_ctx *context); int (*after_sampling)(struct damon_ctx *context); int (*after_aggregation)(struct damon_ctx *context); void (*before_terminate)(struct damon_ctx *context); }; /** * struct damon_ctx - Represents a context for each monitoring. This is the * main interface that allows users to set the attributes and get the results * of the monitoring. * * @sample_interval: The time between access samplings. * @aggr_interval: The time between monitor results aggregations. * @primitive_update_interval: The time between monitoring primitive updates. * * For each @sample_interval, DAMON checks whether each region is accessed or * not. It aggregates and keeps the access information (number of accesses to * each region) for @aggr_interval time. DAMON also checks whether the target * memory regions need update (e.g., by ``mmap()`` calls from the application, * in case of virtual memory monitoring) and applies the changes for each * @primitive_update_interval. All time intervals are in micro-seconds. * Please refer to &struct damon_primitive and &struct damon_callback for more * detail. * * @kdamond: Kernel thread who does the monitoring. * @kdamond_stop: Notifies whether kdamond should stop. * @kdamond_lock: Mutex for the synchronizations with @kdamond. * * For each monitoring context, one kernel thread for the monitoring is * created. The pointer to the thread is stored in @kdamond. * * Once started, the monitoring thread runs until explicitly required to be * terminated or every monitoring target is invalid. The validity of the * targets is checked via the &damon_primitive.target_valid of @primitive. The * termination can also be explicitly requested by writing non-zero to * @kdamond_stop. The thread sets @kdamond to NULL when it terminates. * Therefore, users can know whether the monitoring is ongoing or terminated by * reading @kdamond. Reads and writes to @kdamond and @kdamond_stop from * outside of the monitoring thread must be protected by @kdamond_lock. * * Note that the monitoring thread protects only @kdamond and @kdamond_stop via * @kdamond_lock. Accesses to other fields must be protected by themselves. * * @primitive: Set of monitoring primitives for given use cases. * @callback: Set of callbacks for monitoring events notifications. * * @min_nr_regions: The minimum number of adaptive monitoring regions. * @max_nr_regions: The maximum number of adaptive monitoring regions. * @adaptive_targets: Head of monitoring targets (&damon_target) list. * @schemes: Head of schemes (&damos) list. */ struct damon_ctx { unsigned long sample_interval; unsigned long aggr_interval; unsigned long primitive_update_interval; /* private: internal use only */ struct timespec64 last_aggregation; struct timespec64 last_primitive_update; /* public: */ struct task_struct *kdamond; struct mutex kdamond_lock; struct damon_primitive primitive; struct damon_callback callback; unsigned long min_nr_regions; unsigned long max_nr_regions; struct list_head adaptive_targets; struct list_head schemes; }; #define damon_next_region(r) \ (container_of(r->list.next, struct damon_region, list)) #define damon_prev_region(r) \ (container_of(r->list.prev, struct damon_region, list)) #define damon_last_region(t) \ (list_last_entry(&t->regions_list, struct damon_region, list)) #define damon_for_each_region(r, t) \ list_for_each_entry(r, &t->regions_list, list) #define damon_for_each_region_safe(r, next, t) \ list_for_each_entry_safe(r, next, &t->regions_list, list) #define damon_for_each_target(t, ctx) \ list_for_each_entry(t, &(ctx)->adaptive_targets, list) #define damon_for_each_target_safe(t, next, ctx) \ list_for_each_entry_safe(t, next, &(ctx)->adaptive_targets, list) #define damon_for_each_scheme(s, ctx) \ list_for_each_entry(s, &(ctx)->schemes, list) #define damon_for_each_scheme_safe(s, next, ctx) \ list_for_each_entry_safe(s, next, &(ctx)->schemes, list) #ifdef CONFIG_DAMON struct damon_region *damon_new_region(unsigned long start, unsigned long end); inline void damon_insert_region(struct damon_region *r, struct damon_region *prev, struct damon_region *next, struct damon_target *t); void damon_add_region(struct damon_region *r, struct damon_target *t); void damon_destroy_region(struct damon_region *r, struct damon_target *t); struct damos *damon_new_scheme( unsigned long min_sz_region, unsigned long max_sz_region, unsigned int min_nr_accesses, unsigned int max_nr_accesses, unsigned int min_age_region, unsigned int max_age_region, enum damos_action action, struct damos_quota *quota, struct damos_watermarks *wmarks); void damon_add_scheme(struct damon_ctx *ctx, struct damos *s); void damon_destroy_scheme(struct damos *s); struct damon_target *damon_new_target(unsigned long id); void damon_add_target(struct damon_ctx *ctx, struct damon_target *t); bool damon_targets_empty(struct damon_ctx *ctx); void damon_free_target(struct damon_target *t); void damon_destroy_target(struct damon_target *t); unsigned int damon_nr_regions(struct damon_target *t); struct damon_ctx *damon_new_ctx(void); void damon_destroy_ctx(struct damon_ctx *ctx); int damon_set_targets(struct damon_ctx *ctx, unsigned long *ids, ssize_t nr_ids); int damon_set_attrs(struct damon_ctx *ctx, unsigned long sample_int, unsigned long aggr_int, unsigned long primitive_upd_int, unsigned long min_nr_reg, unsigned long max_nr_reg); int damon_set_schemes(struct damon_ctx *ctx, struct damos **schemes, ssize_t nr_schemes); int damon_nr_running_ctxs(void); int damon_start(struct damon_ctx **ctxs, int nr_ctxs); int damon_stop(struct damon_ctx **ctxs, int nr_ctxs); #endif /* CONFIG_DAMON */ #ifdef CONFIG_DAMON_VADDR /* Monitoring primitives for virtual memory address spaces */ void damon_va_init(struct damon_ctx *ctx); void damon_va_update(struct damon_ctx *ctx); void damon_va_prepare_access_checks(struct damon_ctx *ctx); unsigned int damon_va_check_accesses(struct damon_ctx *ctx); bool damon_va_target_valid(void *t); void damon_va_cleanup(struct damon_ctx *ctx); int damon_va_apply_scheme(struct damon_ctx *context, struct damon_target *t, struct damon_region *r, struct damos *scheme); int damon_va_scheme_score(struct damon_ctx *context, struct damon_target *t, struct damon_region *r, struct damos *scheme); void damon_va_set_primitives(struct damon_ctx *ctx); #endif /* CONFIG_DAMON_VADDR */ #ifdef CONFIG_DAMON_PADDR /* Monitoring primitives for the physical memory address space */ void damon_pa_prepare_access_checks(struct damon_ctx *ctx); unsigned int damon_pa_check_accesses(struct damon_ctx *ctx); bool damon_pa_target_valid(void *t); int damon_pa_apply_scheme(struct damon_ctx *context, struct damon_target *t, struct damon_region *r, struct damos *scheme); int damon_pa_scheme_score(struct damon_ctx *context, struct damon_target *t, struct damon_region *r, struct damos *scheme); void damon_pa_set_primitives(struct damon_ctx *ctx); #endif /* CONFIG_DAMON_PADDR */ #endif /* _DAMON_H */