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 /* for each aggregation interval */
146 0,
147 /* under the quota. */
148 &damon_reclaim_quota,
149 /* (De)activate this according to the watermarks. */
150 &damon_reclaim_wmarks);
151 }
152
damon_reclaim_copy_quota_status(struct damos_quota * dst,struct damos_quota * src)153 static void damon_reclaim_copy_quota_status(struct damos_quota *dst,
154 struct damos_quota *src)
155 {
156 dst->total_charged_sz = src->total_charged_sz;
157 dst->total_charged_ns = src->total_charged_ns;
158 dst->charged_sz = src->charged_sz;
159 dst->charged_from = src->charged_from;
160 dst->charge_target_from = src->charge_target_from;
161 dst->charge_addr_from = src->charge_addr_from;
162 }
163
damon_reclaim_apply_parameters(void)164 static int damon_reclaim_apply_parameters(void)
165 {
166 struct damos *scheme, *old_scheme;
167 struct damos_filter *filter;
168 int err = 0;
169
170 err = damon_set_attrs(ctx, &damon_reclaim_mon_attrs);
171 if (err)
172 return err;
173
174 /* Will be freed by next 'damon_set_schemes()' below */
175 scheme = damon_reclaim_new_scheme();
176 if (!scheme)
177 return -ENOMEM;
178 if (!list_empty(&ctx->schemes)) {
179 damon_for_each_scheme(old_scheme, ctx)
180 damon_reclaim_copy_quota_status(&scheme->quota,
181 &old_scheme->quota);
182 }
183 if (skip_anon) {
184 filter = damos_new_filter(DAMOS_FILTER_TYPE_ANON, true);
185 if (!filter) {
186 /* Will be freed by next 'damon_set_schemes()' below */
187 damon_destroy_scheme(scheme);
188 return -ENOMEM;
189 }
190 damos_add_filter(scheme, filter);
191 }
192 damon_set_schemes(ctx, &scheme, 1);
193
194 return damon_set_region_biggest_system_ram_default(target,
195 &monitor_region_start,
196 &monitor_region_end);
197 }
198
damon_reclaim_turn(bool on)199 static int damon_reclaim_turn(bool on)
200 {
201 int err;
202
203 if (!on) {
204 err = damon_stop(&ctx, 1);
205 if (!err)
206 kdamond_pid = -1;
207 return err;
208 }
209
210 err = damon_reclaim_apply_parameters();
211 if (err)
212 return err;
213
214 err = damon_start(&ctx, 1, true);
215 if (err)
216 return err;
217 kdamond_pid = ctx->kdamond->pid;
218 return 0;
219 }
220
damon_reclaim_enabled_store(const char * val,const struct kernel_param * kp)221 static int damon_reclaim_enabled_store(const char *val,
222 const struct kernel_param *kp)
223 {
224 bool is_enabled = enabled;
225 bool enable;
226 int err;
227
228 err = kstrtobool(val, &enable);
229 if (err)
230 return err;
231
232 if (is_enabled == enable)
233 return 0;
234
235 /* Called before init function. The function will handle this. */
236 if (!ctx)
237 goto set_param_out;
238
239 err = damon_reclaim_turn(enable);
240 if (err)
241 return err;
242
243 set_param_out:
244 enabled = enable;
245 return err;
246 }
247
248 static const struct kernel_param_ops enabled_param_ops = {
249 .set = damon_reclaim_enabled_store,
250 .get = param_get_bool,
251 };
252
253 module_param_cb(enabled, &enabled_param_ops, &enabled, 0600);
254 MODULE_PARM_DESC(enabled,
255 "Enable or disable DAMON_RECLAIM (default: disabled)");
256
damon_reclaim_handle_commit_inputs(void)257 static int damon_reclaim_handle_commit_inputs(void)
258 {
259 int err;
260
261 if (!commit_inputs)
262 return 0;
263
264 err = damon_reclaim_apply_parameters();
265 commit_inputs = false;
266 return err;
267 }
268
damon_reclaim_after_aggregation(struct damon_ctx * c)269 static int damon_reclaim_after_aggregation(struct damon_ctx *c)
270 {
271 struct damos *s;
272
273 /* update the stats parameter */
274 damon_for_each_scheme(s, c)
275 damon_reclaim_stat = s->stat;
276
277 return damon_reclaim_handle_commit_inputs();
278 }
279
damon_reclaim_after_wmarks_check(struct damon_ctx * c)280 static int damon_reclaim_after_wmarks_check(struct damon_ctx *c)
281 {
282 return damon_reclaim_handle_commit_inputs();
283 }
284
damon_reclaim_init(void)285 static int __init damon_reclaim_init(void)
286 {
287 int err = damon_modules_new_paddr_ctx_target(&ctx, &target);
288
289 if (err)
290 return err;
291
292 ctx->callback.after_wmarks_check = damon_reclaim_after_wmarks_check;
293 ctx->callback.after_aggregation = damon_reclaim_after_aggregation;
294
295 /* 'enabled' has set before this function, probably via command line */
296 if (enabled)
297 err = damon_reclaim_turn(true);
298
299 return err;
300 }
301
302 module_init(damon_reclaim_init);
303