1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * DAMON-based page reclamation
4 *
5 * Author: SeongJae Park <sj@kernel.org>
6 */
7
8 #define pr_fmt(fmt) "damon-reclaim: " fmt
9
10 #include <linux/damon.h>
11 #include <linux/kstrtox.h>
12 #include <linux/module.h>
13
14 #include "modules-common.h"
15
16 #ifdef MODULE_PARAM_PREFIX
17 #undef MODULE_PARAM_PREFIX
18 #endif
19 #define MODULE_PARAM_PREFIX "damon_reclaim."
20
21 /*
22 * Enable or disable DAMON_RECLAIM.
23 *
24 * You can enable DAMON_RCLAIM by setting the value of this parameter as ``Y``.
25 * Setting it as ``N`` disables DAMON_RECLAIM. Note that DAMON_RECLAIM could
26 * do no real monitoring and reclamation due to the watermarks-based activation
27 * condition. Refer to below descriptions for the watermarks parameter for
28 * this.
29 */
30 static bool enabled __read_mostly;
31
32 /*
33 * Make DAMON_RECLAIM reads the input parameters again, except ``enabled``.
34 *
35 * Input parameters that updated while DAMON_RECLAIM is running are not applied
36 * by default. Once this parameter is set as ``Y``, DAMON_RECLAIM reads values
37 * of parametrs except ``enabled`` again. Once the re-reading is done, this
38 * parameter is set as ``N``. If invalid parameters are found while the
39 * re-reading, DAMON_RECLAIM will be disabled.
40 */
41 static bool commit_inputs __read_mostly;
42 module_param(commit_inputs, bool, 0600);
43
44 /*
45 * Time threshold for cold memory regions identification in microseconds.
46 *
47 * If a memory region is not accessed for this or longer time, DAMON_RECLAIM
48 * identifies the region as cold, and reclaims. 120 seconds by default.
49 */
50 static unsigned long min_age __read_mostly = 120000000;
51 module_param(min_age, ulong, 0600);
52
53 static struct damos_quota damon_reclaim_quota = {
54 /* use up to 10 ms time, reclaim up to 128 MiB per 1 sec by default */
55 .ms = 10,
56 .sz = 128 * 1024 * 1024,
57 .reset_interval = 1000,
58 /* Within the quota, page out older regions first. */
59 .weight_sz = 0,
60 .weight_nr_accesses = 0,
61 .weight_age = 1
62 };
63 DEFINE_DAMON_MODULES_DAMOS_QUOTAS(damon_reclaim_quota);
64
65 static struct damos_watermarks damon_reclaim_wmarks = {
66 .metric = DAMOS_WMARK_FREE_MEM_RATE,
67 .interval = 5000000, /* 5 seconds */
68 .high = 500, /* 50 percent */
69 .mid = 400, /* 40 percent */
70 .low = 200, /* 20 percent */
71 };
72 DEFINE_DAMON_MODULES_WMARKS_PARAMS(damon_reclaim_wmarks);
73
74 static struct damon_attrs damon_reclaim_mon_attrs = {
75 .sample_interval = 5000, /* 5 ms */
76 .aggr_interval = 100000, /* 100 ms */
77 .ops_update_interval = 0,
78 .min_nr_regions = 10,
79 .max_nr_regions = 1000,
80 };
81 DEFINE_DAMON_MODULES_MON_ATTRS_PARAMS(damon_reclaim_mon_attrs);
82
83 /*
84 * Start of the target memory region in physical address.
85 *
86 * The start physical address of memory region that DAMON_RECLAIM will do work
87 * against. By default, biggest System RAM is used as the region.
88 */
89 static unsigned long monitor_region_start __read_mostly;
90 module_param(monitor_region_start, ulong, 0600);
91
92 /*
93 * End of the target memory region in physical address.
94 *
95 * The end physical address of memory region that DAMON_RECLAIM will do work
96 * against. By default, biggest System RAM is used as the region.
97 */
98 static unsigned long monitor_region_end __read_mostly;
99 module_param(monitor_region_end, ulong, 0600);
100
101 /*
102 * Skip anonymous pages reclamation.
103 *
104 * If this parameter is set as ``Y``, DAMON_RECLAIM does not reclaim anonymous
105 * pages. By default, ``N``.
106 */
107 static bool skip_anon __read_mostly;
108 module_param(skip_anon, bool, 0600);
109
110 /*
111 * PID of the DAMON thread
112 *
113 * If DAMON_RECLAIM is enabled, this becomes the PID of the worker thread.
114 * Else, -1.
115 */
116 static int kdamond_pid __read_mostly = -1;
117 module_param(kdamond_pid, int, 0400);
118
119 static struct damos_stat damon_reclaim_stat;
120 DEFINE_DAMON_MODULES_DAMOS_STATS_PARAMS(damon_reclaim_stat,
121 reclaim_tried_regions, reclaimed_regions, quota_exceeds);
122
123 static struct damon_ctx *ctx;
124 static struct damon_target *target;
125
damon_reclaim_new_scheme(void)126 static struct damos *damon_reclaim_new_scheme(void)
127 {
128 struct damos_access_pattern pattern = {
129 /* Find regions having PAGE_SIZE or larger size */
130 .min_sz_region = PAGE_SIZE,
131 .max_sz_region = ULONG_MAX,
132 /* and not accessed at all */
133 .min_nr_accesses = 0,
134 .max_nr_accesses = 0,
135 /* for min_age or more micro-seconds */
136 .min_age_region = min_age /
137 damon_reclaim_mon_attrs.aggr_interval,
138 .max_age_region = UINT_MAX,
139 };
140
141 return damon_new_scheme(
142 &pattern,
143 /* page out those, as soon as found */
144 DAMOS_PAGEOUT,
145 /* under the quota. */
146 &damon_reclaim_quota,
147 /* (De)activate this according to the watermarks. */
148 &damon_reclaim_wmarks);
149 }
150
damon_reclaim_apply_parameters(void)151 static int damon_reclaim_apply_parameters(void)
152 {
153 struct damos *scheme;
154 struct damos_filter *filter;
155 int err = 0;
156
157 err = damon_set_attrs(ctx, &damon_reclaim_mon_attrs);
158 if (err)
159 return err;
160
161 /* Will be freed by next 'damon_set_schemes()' below */
162 scheme = damon_reclaim_new_scheme();
163 if (!scheme)
164 return -ENOMEM;
165 if (skip_anon) {
166 filter = damos_new_filter(DAMOS_FILTER_TYPE_ANON, true);
167 if (!filter) {
168 /* Will be freed by next 'damon_set_schemes()' below */
169 damon_destroy_scheme(scheme);
170 return -ENOMEM;
171 }
172 damos_add_filter(scheme, filter);
173 }
174 damon_set_schemes(ctx, &scheme, 1);
175
176 return damon_set_region_biggest_system_ram_default(target,
177 &monitor_region_start,
178 &monitor_region_end);
179 }
180
damon_reclaim_turn(bool on)181 static int damon_reclaim_turn(bool on)
182 {
183 int err;
184
185 if (!on) {
186 err = damon_stop(&ctx, 1);
187 if (!err)
188 kdamond_pid = -1;
189 return err;
190 }
191
192 err = damon_reclaim_apply_parameters();
193 if (err)
194 return err;
195
196 err = damon_start(&ctx, 1, true);
197 if (err)
198 return err;
199 kdamond_pid = ctx->kdamond->pid;
200 return 0;
201 }
202
damon_reclaim_enabled_store(const char * val,const struct kernel_param * kp)203 static int damon_reclaim_enabled_store(const char *val,
204 const struct kernel_param *kp)
205 {
206 bool is_enabled = enabled;
207 bool enable;
208 int err;
209
210 err = kstrtobool(val, &enable);
211 if (err)
212 return err;
213
214 if (is_enabled == enable)
215 return 0;
216
217 /* Called before init function. The function will handle this. */
218 if (!ctx)
219 goto set_param_out;
220
221 err = damon_reclaim_turn(enable);
222 if (err)
223 return err;
224
225 set_param_out:
226 enabled = enable;
227 return err;
228 }
229
230 static const struct kernel_param_ops enabled_param_ops = {
231 .set = damon_reclaim_enabled_store,
232 .get = param_get_bool,
233 };
234
235 module_param_cb(enabled, &enabled_param_ops, &enabled, 0600);
236 MODULE_PARM_DESC(enabled,
237 "Enable or disable DAMON_RECLAIM (default: disabled)");
238
damon_reclaim_handle_commit_inputs(void)239 static int damon_reclaim_handle_commit_inputs(void)
240 {
241 int err;
242
243 if (!commit_inputs)
244 return 0;
245
246 err = damon_reclaim_apply_parameters();
247 commit_inputs = false;
248 return err;
249 }
250
damon_reclaim_after_aggregation(struct damon_ctx * c)251 static int damon_reclaim_after_aggregation(struct damon_ctx *c)
252 {
253 struct damos *s;
254
255 /* update the stats parameter */
256 damon_for_each_scheme(s, c)
257 damon_reclaim_stat = s->stat;
258
259 return damon_reclaim_handle_commit_inputs();
260 }
261
damon_reclaim_after_wmarks_check(struct damon_ctx * c)262 static int damon_reclaim_after_wmarks_check(struct damon_ctx *c)
263 {
264 return damon_reclaim_handle_commit_inputs();
265 }
266
damon_reclaim_init(void)267 static int __init damon_reclaim_init(void)
268 {
269 int err = damon_modules_new_paddr_ctx_target(&ctx, &target);
270
271 if (err)
272 return err;
273
274 ctx->callback.after_wmarks_check = damon_reclaim_after_wmarks_check;
275 ctx->callback.after_aggregation = damon_reclaim_after_aggregation;
276
277 /* 'enabled' has set before this function, probably via command line */
278 if (enabled)
279 err = damon_reclaim_turn(true);
280
281 return err;
282 }
283
284 module_init(damon_reclaim_init);
285