diff options
Diffstat (limited to 'include/linux/damon.h')
| -rw-r--r-- | include/linux/damon.h | 581 |
1 files changed, 581 insertions, 0 deletions
diff --git a/include/linux/damon.h b/include/linux/damon.h new file mode 100644 index 000000000..e6941b239 --- /dev/null +++ b/include/linux/damon.h @@ -0,0 +1,581 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * DAMON api + * + * Author: SeongJae Park <sjpark@amazon.de> + */ + +#ifndef _DAMON_H_ +#define _DAMON_H_ + +#include <linux/completion.h> +#include <linux/mutex.h> +#include <linux/time64.h> +#include <linux/types.h> +#include <linux/random.h> + +/* 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) + +/* Get a random number in [l, r) */ +static inline unsigned long damon_rand(unsigned long l, unsigned long r) +{ + return l + prandom_u32_max(r - l); +} + +/** + * 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. + * @pid: The PID of the virtual address space to monitor. + * @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 + * @pid should be set for appropriate &struct damon_operations including the + * virtual address spaces monitoring operations. + */ +struct damon_target { + struct pid *pid; + 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_LRU_PRIO: Prioritize the region on its LRU lists. + * @DAMOS_LRU_DEPRIO: Deprioritize the region on its LRU lists. + * @DAMOS_STAT: Do nothing but count the stat. + * @NR_DAMOS_ACTIONS: Total number of DAMOS actions + */ +enum damos_action { + DAMOS_WILLNEED, + DAMOS_COLD, + DAMOS_PAGEOUT, + DAMOS_HUGEPAGE, + DAMOS_NOHUGEPAGE, + DAMOS_LRU_PRIO, + DAMOS_LRU_DEPRIO, + DAMOS_STAT, /* Do nothing but only record the stat */ + NR_DAMOS_ACTIONS, +}; + +/** + * 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_operations->get_scheme_score. + * You could customize the prioritization logic by setting &weight_sz, + * &weight_nr_accesses, and &weight_age, because monitoring operations 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]. + * @NR_DAMOS_WMARK_METRICS: Total number of DAMOS watermark metrics + */ +enum damos_wmark_metric { + DAMOS_WMARK_NONE, + DAMOS_WMARK_FREE_MEM_RATE, + NR_DAMOS_WMARK_METRICS, +}; + +/** + * 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_stat - Statistics on a given scheme. + * @nr_tried: Total number of regions that the scheme is tried to be applied. + * @sz_tried: Total size of regions that the scheme is tried to be applied. + * @nr_applied: Total number of regions that the scheme is applied. + * @sz_applied: Total size of regions that the scheme is applied. + * @qt_exceeds: Total number of times the quota of the scheme has exceeded. + */ +struct damos_stat { + unsigned long nr_tried; + unsigned long sz_tried; + unsigned long nr_applied; + unsigned long sz_applied; + unsigned long qt_exceeds; +}; + +/** + * struct damos_access_pattern - Target access pattern of the given 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. + */ +struct damos_access_pattern { + 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; +}; + +/** + * struct damos - Represents a Data Access Monitoring-based Operation Scheme. + * @pattern: Access pattern 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: Statistics of this scheme. + * @list: List head for siblings. + * + * For each aggregation interval, DAMON finds regions which fit in the + * &pattern 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 { + struct damos_access_pattern pattern; + enum damos_action action; + struct damos_quota quota; + struct damos_watermarks wmarks; + struct damos_stat stat; + struct list_head list; +}; + +/** + * enum damon_ops_id - Identifier for each monitoring operations implementation + * + * @DAMON_OPS_VADDR: Monitoring operations for virtual address spaces + * @DAMON_OPS_FVADDR: Monitoring operations for only fixed ranges of virtual + * address spaces + * @DAMON_OPS_PADDR: Monitoring operations for the physical address space + * @NR_DAMON_OPS: Number of monitoring operations implementations + */ +enum damon_ops_id { + DAMON_OPS_VADDR, + DAMON_OPS_FVADDR, + DAMON_OPS_PADDR, + NR_DAMON_OPS, +}; + +struct damon_ctx; + +/** + * struct damon_operations - Monitoring operations for given use cases. + * + * @id: Identifier of this operations set. + * @init: Initialize operations-related data structures. + * @update: Update operations-related 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 operations for their target address + * space and usecase via the &damon_ctx.ops. Then, the monitoring thread + * (&damon_ctx.kdamond) calls @init and @prepare_access_checks before starting + * the monitoring, @update after each &damon_ctx.ops_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. + * + * Each &struct damon_operations instance having valid @id can be registered + * via damon_register_ops() and selected by damon_select_ops() later. + * @init should initialize operations-related 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 operations-related 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 and return bytes of the region that the action is successfully + * applied. + * @target_valid should check whether the target is still valid for the + * monitoring. + * @cleanup is called from @kdamond just before its termination. + */ +struct damon_operations { + enum damon_ops_id id; + 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); + unsigned long (*apply_scheme)(struct damon_ctx *context, + struct damon_target *t, struct damon_region *r, + struct damos *scheme); + bool (*target_valid)(struct damon_target *t); + void (*cleanup)(struct damon_ctx *context); +}; + +/** + * struct damon_callback - Monitoring events notification callbacks. + * + * @before_start: Called before starting the monitoring. + * @after_wmarks_check: Called after each schemes' watermarks check. + * @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_wmarks_check after each DAMON-based + * operation schemes' watermarks check. If users need to make changes to the + * attributes of the monitoring context while it's deactivated due to the + * watermarks, this is the good place to do. + * + * 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_wmarks_check)(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_attrs - Monitoring attributes for accuracy/overhead control. + * + * @sample_interval: The time between access samplings. + * @aggr_interval: The time between monitor results aggregations. + * @ops_update_interval: The time between monitoring operations updates. + * @min_nr_regions: The minimum number of adaptive monitoring + * regions. + * @max_nr_regions: The maximum number of adaptive monitoring + * regions. + * + * 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 + * @ops_update_interval. All time intervals are in micro-seconds. + * Please refer to &struct damon_operations and &struct damon_callback for more + * detail. + */ +struct damon_attrs { + unsigned long sample_interval; + unsigned long aggr_interval; + unsigned long ops_update_interval; + unsigned long min_nr_regions; + unsigned long max_nr_regions; +}; + +/** + * 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. + * + * @attrs: Monitoring attributes for accuracy/overhead control. + * @kdamond: Kernel thread who does the monitoring. + * @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_operations.target_valid of @ops. The + * termination can also be explicitly requested by calling damon_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 from outside of the monitoring thread must + * be protected by @kdamond_lock. + * + * Note that the monitoring thread protects only @kdamond via @kdamond_lock. + * Accesses to other fields must be protected by themselves. + * + * @ops: Set of monitoring operations for given use cases. + * @callback: Set of callbacks for monitoring events notifications. + * + * @adaptive_targets: Head of monitoring targets (&damon_target) list. + * @schemes: Head of schemes (&damos) list. + */ +struct damon_ctx { + struct damon_attrs attrs; + +/* private: internal use only */ + struct timespec64 last_aggregation; + struct timespec64 last_ops_update; + /* for waiting until the execution of the kdamond_fn is started */ + struct completion kdamond_started; + +/* public: */ + struct task_struct *kdamond; + struct mutex kdamond_lock; + + struct damon_operations ops; + struct damon_callback callback; + + struct list_head adaptive_targets; + struct list_head schemes; +}; + +static inline struct damon_region *damon_next_region(struct damon_region *r) +{ + return container_of(r->list.next, struct damon_region, list); +} + +static inline struct damon_region *damon_prev_region(struct damon_region *r) +{ + return container_of(r->list.prev, struct damon_region, list); +} + +static inline struct damon_region *damon_last_region(struct damon_target *t) +{ + return list_last_entry(&t->regions_list, struct damon_region, list); +} + +static inline struct damon_region *damon_first_region(struct damon_target *t) +{ + return list_first_entry(&t->regions_list, struct damon_region, list); +} + +static inline unsigned long damon_sz_region(struct damon_region *r) +{ + return r->ar.end - r->ar.start; +} + + +#define damon_for_each_region(r, t) \ + list_for_each_entry(r, &t->regions_list, list) + +#define damon_for_each_region_from(r, t) \ + list_for_each_entry_from(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); + +/* + * Add a region between two other regions + */ +static inline void damon_insert_region(struct damon_region *r, + struct damon_region *prev, struct damon_region *next, + struct damon_target *t) +{ + __list_add(&r->list, &prev->list, &next->list); + t->nr_regions++; +} + +void damon_add_region(struct damon_region *r, struct damon_target *t); +void damon_destroy_region(struct damon_region *r, struct damon_target *t); +int damon_set_regions(struct damon_target *t, struct damon_addr_range *ranges, + unsigned int nr_ranges); + +struct damos *damon_new_scheme(struct damos_access_pattern *pattern, + 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(void); +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_attrs(struct damon_ctx *ctx, struct damon_attrs *attrs); +void damon_set_schemes(struct damon_ctx *ctx, + struct damos **schemes, ssize_t nr_schemes); +int damon_nr_running_ctxs(void); +bool damon_is_registered_ops(enum damon_ops_id id); +int damon_register_ops(struct damon_operations *ops); +int damon_select_ops(struct damon_ctx *ctx, enum damon_ops_id id); + +static inline bool damon_target_has_pid(const struct damon_ctx *ctx) +{ + return ctx->ops.id == DAMON_OPS_VADDR || ctx->ops.id == DAMON_OPS_FVADDR; +} + +static inline unsigned int damon_max_nr_accesses(const struct damon_attrs *attrs) +{ + /* {aggr,sample}_interval are unsigned long, hence could overflow */ + return min(attrs->aggr_interval / attrs->sample_interval, + (unsigned long)UINT_MAX); +} + + +int damon_start(struct damon_ctx **ctxs, int nr_ctxs, bool exclusive); +int damon_stop(struct damon_ctx **ctxs, int nr_ctxs); + +int damon_set_region_biggest_system_ram_default(struct damon_target *t, + unsigned long *start, unsigned long *end); + +#endif /* CONFIG_DAMON */ + +#endif /* _DAMON_H */ |