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 /*
66 * Desired level of memory pressure-stall time in microseconds.
67 *
68 * While keeping the caps that set by other quotas, DAMON_RECLAIM automatically
69 * increases and decreases the effective level of the quota aiming this level of
70 * memory pressure is incurred. System-wide ``some`` memory PSI in microseconds
71 * per quota reset interval (``quota_reset_interval_ms``) is collected and
72 * compared to this value to see if the aim is satisfied. Value zero means
73 * disabling this auto-tuning feature.
74 *
75 * Disabled by default.
76 */
77 static unsigned long quota_mem_pressure_us __read_mostly;
78 module_param(quota_mem_pressure_us, ulong, 0600);
79
80 /*
81 * User-specifiable feedback for auto-tuning of the effective quota.
82 *
83 * While keeping the caps that set by other quotas, DAMON_RECLAIM automatically
84 * increases and decreases the effective level of the quota aiming receiving this
85 * feedback of value ``10,000`` from the user. DAMON_RECLAIM assumes the feedback
86 * value and the quota are positively proportional. Value zero means disabling
87 * this auto-tuning feature.
88 *
89 * Disabled by default.
90 *
91 */
92 static unsigned long quota_autotune_feedback __read_mostly;
93 module_param(quota_autotune_feedback, ulong, 0600);
94
95 static struct damos_watermarks damon_reclaim_wmarks = {
96 .metric = DAMOS_WMARK_FREE_MEM_RATE,
97 .interval = 5000000, /* 5 seconds */
98 .high = 500, /* 50 percent */
99 .mid = 400, /* 40 percent */
100 .low = 200, /* 20 percent */
101 };
102 DEFINE_DAMON_MODULES_WMARKS_PARAMS(damon_reclaim_wmarks);
103
104 static struct damon_attrs damon_reclaim_mon_attrs = {
105 .sample_interval = 5000, /* 5 ms */
106 .aggr_interval = 100000, /* 100 ms */
107 .ops_update_interval = 0,
108 .min_nr_regions = 10,
109 .max_nr_regions = 1000,
110 };
111 DEFINE_DAMON_MODULES_MON_ATTRS_PARAMS(damon_reclaim_mon_attrs);
112
113 /*
114 * Start of the target memory region in physical address.
115 *
116 * The start physical address of memory region that DAMON_RECLAIM will do work
117 * against. By default, biggest System RAM is used as the region.
118 */
119 static unsigned long monitor_region_start __read_mostly;
120 module_param(monitor_region_start, ulong, 0600);
121
122 /*
123 * End of the target memory region in physical address.
124 *
125 * The end physical address of memory region that DAMON_RECLAIM will do work
126 * against. By default, biggest System RAM is used as the region.
127 */
128 static unsigned long monitor_region_end __read_mostly;
129 module_param(monitor_region_end, ulong, 0600);
130
131 /*
132 * Skip anonymous pages reclamation.
133 *
134 * If this parameter is set as ``Y``, DAMON_RECLAIM does not reclaim anonymous
135 * pages. By default, ``N``.
136 */
137 static bool skip_anon __read_mostly;
138 module_param(skip_anon, bool, 0600);
139
140 /*
141 * PID of the DAMON thread
142 *
143 * If DAMON_RECLAIM is enabled, this becomes the PID of the worker thread.
144 * Else, -1.
145 */
146 static int kdamond_pid __read_mostly = -1;
147 module_param(kdamond_pid, int, 0400);
148
149 static struct damos_stat damon_reclaim_stat;
150 DEFINE_DAMON_MODULES_DAMOS_STATS_PARAMS(damon_reclaim_stat,
151 reclaim_tried_regions, reclaimed_regions, quota_exceeds);
152
153 static struct damon_ctx *ctx;
154 static struct damon_target *target;
155
156 static struct damos *damon_reclaim_new_scheme(void)
157 {
158 struct damos_access_pattern pattern = {
159 /* Find regions having PAGE_SIZE or larger size */
160 .min_sz_region = PAGE_SIZE,
161 .max_sz_region = ULONG_MAX,
162 /* and not accessed at all */
163 .min_nr_accesses = 0,
164 .max_nr_accesses = 0,
165 /* for min_age or more micro-seconds */
166 .min_age_region = min_age /
167 damon_reclaim_mon_attrs.aggr_interval,
168 .max_age_region = UINT_MAX,
169 };
170
171 return damon_new_scheme(
172 &pattern,
173 /* page out those, as soon as found */
174 DAMOS_PAGEOUT,
175 /* for each aggregation interval */
176 0,
177 /* under the quota. */
178 &damon_reclaim_quota,
179 /* (De)activate this according to the watermarks. */
180 &damon_reclaim_wmarks,
181 NUMA_NO_NODE);
182 }
183
184 static int damon_reclaim_apply_parameters(void)
185 {
186 struct damon_ctx *param_ctx;
187 struct damon_target *param_target;
188 struct damos *scheme;
189 struct damos_quota_goal *goal;
190 struct damos_filter *filter;
191 int err;
192
193 err = damon_modules_new_paddr_ctx_target(¶m_ctx, ¶m_target);
194 if (err)
195 return err;
196
197 err = damon_set_attrs(ctx, &damon_reclaim_mon_attrs);
198 if (err)
199 goto out;
200
201 err = -ENOMEM;
202 scheme = damon_reclaim_new_scheme();
203 if (!scheme)
204 goto out;
205 damon_set_schemes(ctx, &scheme, 1);
206
207 if (quota_mem_pressure_us) {
208 goal = damos_new_quota_goal(DAMOS_QUOTA_SOME_MEM_PSI_US,
209 quota_mem_pressure_us);
210 if (!goal)
211 goto out;
212 damos_add_quota_goal(&scheme->quota, goal);
213 }
214
215 if (quota_autotune_feedback) {
216 goal = damos_new_quota_goal(DAMOS_QUOTA_USER_INPUT, 10000);
217 if (!goal)
218 goto out;
219 goal->current_value = quota_autotune_feedback;
220 damos_add_quota_goal(&scheme->quota, goal);
221 }
222
223 if (skip_anon) {
224 filter = damos_new_filter(DAMOS_FILTER_TYPE_ANON, true);
225 if (!filter)
226 goto out;
227 damos_add_filter(scheme, filter);
228 }
229
230 err = damon_set_region_biggest_system_ram_default(param_target,
231 &monitor_region_start,
232 &monitor_region_end);
233 if (err)
234 goto out;
235 err = damon_commit_ctx(ctx, param_ctx);
236 out:
237 damon_destroy_ctx(param_ctx);
238 return err;
239 }
240
241 static int damon_reclaim_turn(bool on)
242 {
243 int err;
244
245 if (!on) {
246 err = damon_stop(&ctx, 1);
247 if (!err)
248 kdamond_pid = -1;
249 return err;
250 }
251
252 err = damon_reclaim_apply_parameters();
253 if (err)
254 return err;
255
256 err = damon_start(&ctx, 1, true);
257 if (err)
258 return err;
259 kdamond_pid = ctx->kdamond->pid;
260 return 0;
261 }
262
263 static int damon_reclaim_enabled_store(const char *val,
264 const struct kernel_param *kp)
265 {
266 bool is_enabled = enabled;
267 bool enable;
268 int err;
269
270 err = kstrtobool(val, &enable);
271 if (err)
272 return err;
273
274 if (is_enabled == enable)
275 return 0;
276
277 /* Called before init function. The function will handle this. */
278 if (!ctx)
279 goto set_param_out;
280
281 err = damon_reclaim_turn(enable);
282 if (err)
283 return err;
284
285 set_param_out:
286 enabled = enable;
287 return err;
288 }
289
290 static const struct kernel_param_ops enabled_param_ops = {
291 .set = damon_reclaim_enabled_store,
292 .get = param_get_bool,
293 };
294
295 module_param_cb(enabled, &enabled_param_ops, &enabled, 0600);
296 MODULE_PARM_DESC(enabled,
297 "Enable or disable DAMON_RECLAIM (default: disabled)");
298
299 static int damon_reclaim_handle_commit_inputs(void)
300 {
301 int err;
302
303 if (!commit_inputs)
304 return 0;
305
306 err = damon_reclaim_apply_parameters();
307 commit_inputs = false;
308 return err;
309 }
310
311 static int damon_reclaim_after_aggregation(struct damon_ctx *c)
312 {
313 struct damos *s;
314
315 /* update the stats parameter */
316 damon_for_each_scheme(s, c)
317 damon_reclaim_stat = s->stat;
318
319 return damon_reclaim_handle_commit_inputs();
320 }
321
322 static int damon_reclaim_after_wmarks_check(struct damon_ctx *c)
323 {
324 return damon_reclaim_handle_commit_inputs();
325 }
326
327 static int __init damon_reclaim_init(void)
328 {
329 int err = damon_modules_new_paddr_ctx_target(&ctx, &target);
330
331 if (err)
332 return err;
333
334 ctx->callback.after_wmarks_check = damon_reclaim_after_wmarks_check;
335 ctx->callback.after_aggregation = damon_reclaim_after_aggregation;
336
337 /* 'enabled' has set before this function, probably via command line */
338 if (enabled)
339 err = damon_reclaim_turn(true);
340
341 return err;
342 }
343
344 module_init(damon_reclaim_init);
345
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.