1 /* SPDX-License-Identifier: GPL-2.0 */
5 * Author: SeongJae Park <sjpark@amazon.de>
11 #include <linux/mutex.h>
12 #include <linux/time64.h>
13 #include <linux/types.h>
15 /* Minimal region size. Every damon_region is aligned by this. */
16 #define DAMON_MIN_REGION PAGE_SIZE
19 * struct damon_addr_range - Represents an address region of [@start, @end).
20 * @start: Start address of the region (inclusive).
21 * @end: End address of the region (exclusive).
23 struct damon_addr_range {
29 * struct damon_region - Represents a monitoring target region.
30 * @ar: The address range of the region.
31 * @sampling_addr: Address of the sample for the next access check.
32 * @nr_accesses: Access frequency of this region.
33 * @list: List head for siblings.
34 * @age: Age of this region.
36 * @age is initially zero, increased for each aggregation interval, and reset
37 * to zero again if the access frequency is significantly changed. If two
38 * regions are merged into a new region, both @nr_accesses and @age of the new
39 * region are set as region size-weighted average of those of the two regions.
42 struct damon_addr_range ar;
43 unsigned long sampling_addr;
44 unsigned int nr_accesses;
45 struct list_head list;
48 /* private: Internal value for age calculation. */
49 unsigned int last_nr_accesses;
53 * struct damon_target - Represents a monitoring target.
54 * @id: Unique identifier for this target.
55 * @nr_regions: Number of monitoring target regions of this target.
56 * @regions_list: Head of the monitoring target regions of this target.
57 * @list: List head for siblings.
59 * Each monitoring context could have multiple targets. For example, a context
60 * for virtual memory address spaces could have multiple target processes. The
61 * @id of each target should be unique among the targets of the context. For
62 * example, in the virtual address monitoring context, it could be a pidfd or
63 * an address of an mm_struct.
67 unsigned int nr_regions;
68 struct list_head regions_list;
69 struct list_head list;
75 * struct damon_primitive - Monitoring primitives for given use cases.
77 * @init: Initialize primitive-internal data structures.
78 * @update: Update primitive-internal data structures.
79 * @prepare_access_checks: Prepare next access check of target regions.
80 * @check_accesses: Check the accesses to target regions.
81 * @reset_aggregated: Reset aggregated accesses monitoring results.
82 * @target_valid: Determine if the target is valid.
83 * @cleanup: Clean up the context.
85 * DAMON can be extended for various address spaces and usages. For this,
86 * users should register the low level primitives for their target address
87 * space and usecase via the &damon_ctx.primitive. Then, the monitoring thread
88 * (&damon_ctx.kdamond) calls @init and @prepare_access_checks before starting
89 * the monitoring, @update after each &damon_ctx.primitive_update_interval, and
90 * @check_accesses, @target_valid and @prepare_access_checks after each
91 * &damon_ctx.sample_interval. Finally, @reset_aggregated is called after each
92 * &damon_ctx.aggr_interval.
94 * @init should initialize primitive-internal data structures. For example,
95 * this could be used to construct proper monitoring target regions and link
96 * those to @damon_ctx.adaptive_targets.
97 * @update should update the primitive-internal data structures. For example,
98 * this could be used to update monitoring target regions for current status.
99 * @prepare_access_checks should manipulate the monitoring regions to be
100 * prepared for the next access check.
101 * @check_accesses should check the accesses to each region that made after the
102 * last preparation and update the number of observed accesses of each region.
103 * It should also return max number of observed accesses that made as a result
104 * of its update. The value will be used for regions adjustment threshold.
105 * @reset_aggregated should reset the access monitoring results that aggregated
106 * by @check_accesses.
107 * @target_valid should check whether the target is still valid for the
109 * @cleanup is called from @kdamond just before its termination.
111 struct damon_primitive {
112 void (*init)(struct damon_ctx *context);
113 void (*update)(struct damon_ctx *context);
114 void (*prepare_access_checks)(struct damon_ctx *context);
115 unsigned int (*check_accesses)(struct damon_ctx *context);
116 void (*reset_aggregated)(struct damon_ctx *context);
117 bool (*target_valid)(void *target);
118 void (*cleanup)(struct damon_ctx *context);
122 * struct damon_callback - Monitoring events notification callbacks.
124 * @before_start: Called before starting the monitoring.
125 * @after_sampling: Called after each sampling.
126 * @after_aggregation: Called after each aggregation.
127 * @before_terminate: Called before terminating the monitoring.
128 * @private: User private data.
130 * The monitoring thread (&damon_ctx.kdamond) calls @before_start and
131 * @before_terminate just before starting and finishing the monitoring,
132 * respectively. Therefore, those are good places for installing and cleaning
135 * The monitoring thread calls @after_sampling and @after_aggregation for each
136 * of the sampling intervals and aggregation intervals, respectively.
137 * Therefore, users can safely access the monitoring results without additional
138 * protection. For the reason, users are recommended to use these callback for
139 * the accesses to the results.
141 * If any callback returns non-zero, monitoring stops.
143 struct damon_callback {
146 int (*before_start)(struct damon_ctx *context);
147 int (*after_sampling)(struct damon_ctx *context);
148 int (*after_aggregation)(struct damon_ctx *context);
149 int (*before_terminate)(struct damon_ctx *context);
153 * struct damon_ctx - Represents a context for each monitoring. This is the
154 * main interface that allows users to set the attributes and get the results
157 * @sample_interval: The time between access samplings.
158 * @aggr_interval: The time between monitor results aggregations.
159 * @primitive_update_interval: The time between monitoring primitive updates.
161 * For each @sample_interval, DAMON checks whether each region is accessed or
162 * not. It aggregates and keeps the access information (number of accesses to
163 * each region) for @aggr_interval time. DAMON also checks whether the target
164 * memory regions need update (e.g., by ``mmap()`` calls from the application,
165 * in case of virtual memory monitoring) and applies the changes for each
166 * @primitive_update_interval. All time intervals are in micro-seconds.
167 * Please refer to &struct damon_primitive and &struct damon_callback for more
170 * @kdamond: Kernel thread who does the monitoring.
171 * @kdamond_stop: Notifies whether kdamond should stop.
172 * @kdamond_lock: Mutex for the synchronizations with @kdamond.
174 * For each monitoring context, one kernel thread for the monitoring is
175 * created. The pointer to the thread is stored in @kdamond.
177 * Once started, the monitoring thread runs until explicitly required to be
178 * terminated or every monitoring target is invalid. The validity of the
179 * targets is checked via the &damon_primitive.target_valid of @primitive. The
180 * termination can also be explicitly requested by writing non-zero to
181 * @kdamond_stop. The thread sets @kdamond to NULL when it terminates.
182 * Therefore, users can know whether the monitoring is ongoing or terminated by
183 * reading @kdamond. Reads and writes to @kdamond and @kdamond_stop from
184 * outside of the monitoring thread must be protected by @kdamond_lock.
186 * Note that the monitoring thread protects only @kdamond and @kdamond_stop via
187 * @kdamond_lock. Accesses to other fields must be protected by themselves.
189 * @primitive: Set of monitoring primitives for given use cases.
190 * @callback: Set of callbacks for monitoring events notifications.
192 * @min_nr_regions: The minimum number of adaptive monitoring regions.
193 * @max_nr_regions: The maximum number of adaptive monitoring regions.
194 * @adaptive_targets: Head of monitoring targets (&damon_target) list.
197 unsigned long sample_interval;
198 unsigned long aggr_interval;
199 unsigned long primitive_update_interval;
201 /* private: internal use only */
202 struct timespec64 last_aggregation;
203 struct timespec64 last_primitive_update;
206 struct task_struct *kdamond;
208 struct mutex kdamond_lock;
210 struct damon_primitive primitive;
211 struct damon_callback callback;
213 unsigned long min_nr_regions;
214 unsigned long max_nr_regions;
215 struct list_head adaptive_targets;
218 #define damon_next_region(r) \
219 (container_of(r->list.next, struct damon_region, list))
221 #define damon_prev_region(r) \
222 (container_of(r->list.prev, struct damon_region, list))
224 #define damon_for_each_region(r, t) \
225 list_for_each_entry(r, &t->regions_list, list)
227 #define damon_for_each_region_safe(r, next, t) \
228 list_for_each_entry_safe(r, next, &t->regions_list, list)
230 #define damon_for_each_target(t, ctx) \
231 list_for_each_entry(t, &(ctx)->adaptive_targets, list)
233 #define damon_for_each_target_safe(t, next, ctx) \
234 list_for_each_entry_safe(t, next, &(ctx)->adaptive_targets, list)
238 struct damon_region *damon_new_region(unsigned long start, unsigned long end);
239 inline void damon_insert_region(struct damon_region *r,
240 struct damon_region *prev, struct damon_region *next,
241 struct damon_target *t);
242 void damon_add_region(struct damon_region *r, struct damon_target *t);
243 void damon_destroy_region(struct damon_region *r, struct damon_target *t);
245 struct damon_target *damon_new_target(unsigned long id);
246 void damon_add_target(struct damon_ctx *ctx, struct damon_target *t);
247 void damon_free_target(struct damon_target *t);
248 void damon_destroy_target(struct damon_target *t);
249 unsigned int damon_nr_regions(struct damon_target *t);
251 struct damon_ctx *damon_new_ctx(void);
252 void damon_destroy_ctx(struct damon_ctx *ctx);
253 int damon_set_targets(struct damon_ctx *ctx,
254 unsigned long *ids, ssize_t nr_ids);
255 int damon_set_attrs(struct damon_ctx *ctx, unsigned long sample_int,
256 unsigned long aggr_int, unsigned long primitive_upd_int,
257 unsigned long min_nr_reg, unsigned long max_nr_reg);
258 int damon_nr_running_ctxs(void);
260 int damon_start(struct damon_ctx **ctxs, int nr_ctxs);
261 int damon_stop(struct damon_ctx **ctxs, int nr_ctxs);
263 #endif /* CONFIG_DAMON */
265 #ifdef CONFIG_DAMON_VADDR
267 /* Monitoring primitives for virtual memory address spaces */
268 void damon_va_init(struct damon_ctx *ctx);
269 void damon_va_update(struct damon_ctx *ctx);
270 void damon_va_prepare_access_checks(struct damon_ctx *ctx);
271 unsigned int damon_va_check_accesses(struct damon_ctx *ctx);
272 bool damon_va_target_valid(void *t);
273 void damon_va_cleanup(struct damon_ctx *ctx);
274 void damon_va_set_primitives(struct damon_ctx *ctx);
276 #endif /* CONFIG_DAMON_VADDR */
278 #endif /* _DAMON_H */