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>
18 * struct damon_primitive Monitoring primitives for given use cases.
20 * @init: Initialize primitive-internal data structures.
21 * @update: Update primitive-internal data structures.
22 * @prepare_access_checks: Prepare next access check of target regions.
23 * @check_accesses: Check the accesses to target regions.
24 * @reset_aggregated: Reset aggregated accesses monitoring results.
25 * @target_valid: Determine if the target is valid.
26 * @cleanup: Clean up the context.
28 * DAMON can be extended for various address spaces and usages. For this,
29 * users should register the low level primitives for their target address
30 * space and usecase via the &damon_ctx.primitive. Then, the monitoring thread
31 * (&damon_ctx.kdamond) calls @init and @prepare_access_checks before starting
32 * the monitoring, @update after each &damon_ctx.primitive_update_interval, and
33 * @check_accesses, @target_valid and @prepare_access_checks after each
34 * &damon_ctx.sample_interval. Finally, @reset_aggregated is called after each
35 * &damon_ctx.aggr_interval.
37 * @init should initialize primitive-internal data structures. For example,
38 * this could be used to construct proper monitoring target regions and link
39 * those to @damon_ctx.target.
40 * @update should update the primitive-internal data structures. For example,
41 * this could be used to update monitoring target regions for current status.
42 * @prepare_access_checks should manipulate the monitoring regions to be
43 * prepared for the next access check.
44 * @check_accesses should check the accesses to each region that made after the
45 * last preparation and update the number of observed accesses of each region.
46 * @reset_aggregated should reset the access monitoring results that aggregated
48 * @target_valid should check whether the target is still valid for the
50 * @cleanup is called from @kdamond just before its termination.
52 struct damon_primitive {
53 void (*init)(struct damon_ctx *context);
54 void (*update)(struct damon_ctx *context);
55 void (*prepare_access_checks)(struct damon_ctx *context);
56 void (*check_accesses)(struct damon_ctx *context);
57 void (*reset_aggregated)(struct damon_ctx *context);
58 bool (*target_valid)(void *target);
59 void (*cleanup)(struct damon_ctx *context);
63 * struct damon_callback Monitoring events notification callbacks.
65 * @before_start: Called before starting the monitoring.
66 * @after_sampling: Called after each sampling.
67 * @after_aggregation: Called after each aggregation.
68 * @before_terminate: Called before terminating the monitoring.
69 * @private: User private data.
71 * The monitoring thread (&damon_ctx.kdamond) calls @before_start and
72 * @before_terminate just before starting and finishing the monitoring,
73 * respectively. Therefore, those are good places for installing and cleaning
76 * The monitoring thread calls @after_sampling and @after_aggregation for each
77 * of the sampling intervals and aggregation intervals, respectively.
78 * Therefore, users can safely access the monitoring results without additional
79 * protection. For the reason, users are recommended to use these callback for
80 * the accesses to the results.
82 * If any callback returns non-zero, monitoring stops.
84 struct damon_callback {
87 int (*before_start)(struct damon_ctx *context);
88 int (*after_sampling)(struct damon_ctx *context);
89 int (*after_aggregation)(struct damon_ctx *context);
90 int (*before_terminate)(struct damon_ctx *context);
94 * struct damon_ctx - Represents a context for each monitoring. This is the
95 * main interface that allows users to set the attributes and get the results
98 * @sample_interval: The time between access samplings.
99 * @aggr_interval: The time between monitor results aggregations.
100 * @primitive_update_interval: The time between monitoring primitive updates.
102 * For each @sample_interval, DAMON checks whether each region is accessed or
103 * not. It aggregates and keeps the access information (number of accesses to
104 * each region) for @aggr_interval time. DAMON also checks whether the target
105 * memory regions need update (e.g., by ``mmap()`` calls from the application,
106 * in case of virtual memory monitoring) and applies the changes for each
107 * @primitive_update_interval. All time intervals are in micro-seconds.
108 * Please refer to &struct damon_primitive and &struct damon_callback for more
111 * @kdamond: Kernel thread who does the monitoring.
112 * @kdamond_stop: Notifies whether kdamond should stop.
113 * @kdamond_lock: Mutex for the synchronizations with @kdamond.
115 * For each monitoring context, one kernel thread for the monitoring is
116 * created. The pointer to the thread is stored in @kdamond.
118 * Once started, the monitoring thread runs until explicitly required to be
119 * terminated or every monitoring target is invalid. The validity of the
120 * targets is checked via the &damon_primitive.target_valid of @primitive. The
121 * termination can also be explicitly requested by writing non-zero to
122 * @kdamond_stop. The thread sets @kdamond to NULL when it terminates.
123 * Therefore, users can know whether the monitoring is ongoing or terminated by
124 * reading @kdamond. Reads and writes to @kdamond and @kdamond_stop from
125 * outside of the monitoring thread must be protected by @kdamond_lock.
127 * Note that the monitoring thread protects only @kdamond and @kdamond_stop via
128 * @kdamond_lock. Accesses to other fields must be protected by themselves.
130 * @primitive: Set of monitoring primitives for given use cases.
131 * @callback: Set of callbacks for monitoring events notifications.
133 * @target: Pointer to the user-defined monitoring target.
136 unsigned long sample_interval;
137 unsigned long aggr_interval;
138 unsigned long primitive_update_interval;
140 /* private: internal use only */
141 struct timespec64 last_aggregation;
142 struct timespec64 last_primitive_update;
145 struct task_struct *kdamond;
147 struct mutex kdamond_lock;
149 struct damon_primitive primitive;
150 struct damon_callback callback;
157 struct damon_ctx *damon_new_ctx(void);
158 void damon_destroy_ctx(struct damon_ctx *ctx);
159 int damon_set_attrs(struct damon_ctx *ctx, unsigned long sample_int,
160 unsigned long aggr_int, unsigned long primitive_upd_int);
162 int damon_start(struct damon_ctx **ctxs, int nr_ctxs);
163 int damon_stop(struct damon_ctx **ctxs, int nr_ctxs);
165 #endif /* CONFIG_DAMON */
167 #endif /* _DAMON_H */