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Diffstat (limited to 'include/linux/damon.h')
| -rw-r--r-- | include/linux/damon.h | 268 |
1 files changed, 268 insertions, 0 deletions
diff --git a/include/linux/damon.h b/include/linux/damon.h new file mode 100644 index 000000000000..d68b67b8d458 --- /dev/null +++ b/include/linux/damon.h @@ -0,0 +1,268 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * DAMON api + * + * Author: SeongJae Park <sjpark@amazon.de> + */ + +#ifndef _DAMON_H_ +#define _DAMON_H_ + +#include <linux/mutex.h> +#include <linux/time64.h> +#include <linux/types.h> + +/* Minimal region size. Every damon_region is aligned by this. */ +#define DAMON_MIN_REGION PAGE_SIZE + +/** + * 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. + */ +struct damon_region { + struct damon_addr_range ar; + unsigned long sampling_addr; + unsigned int nr_accesses; + struct list_head list; +}; + +/** + * 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; +}; + +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. + * @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. + * @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); + 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); + int (*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. + */ +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; + bool kdamond_stop; + 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; +}; + +#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_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) + +#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 damon_target *damon_new_target(unsigned long id); +void damon_add_target(struct damon_ctx *ctx, struct damon_target *t); +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_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); +void damon_va_set_primitives(struct damon_ctx *ctx); + +#endif /* CONFIG_DAMON_VADDR */ + +#endif /* _DAMON_H */ |