1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * DAMON-based LRU-lists Sorting
4 *
5 * Author: SeongJae Park <sj@kernel.org>
6 */
7
8 #define pr_fmt(fmt) "damon-lru-sort: " 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_lru_sort."
20
21 /*
22 * Enable or disable DAMON_LRU_SORT.
23 *
24 * You can enable DAMON_LRU_SORT by setting the value of this parameter as
25 * ``Y``. Setting it as ``N`` disables DAMON_LRU_SORT. Note that
26 * DAMON_LRU_SORT could do no real monitoring and LRU-lists sorting due to the
27 * watermarks-based activation condition. Refer to below descriptions for the
28 * watermarks parameter for this.
29 */
30 static bool enabled __read_mostly;
31
32 /*
33 * Make DAMON_LRU_SORT reads the input parameters again, except ``enabled``.
34 *
35 * Input parameters that updated while DAMON_LRU_SORT is running are not
36 * applied by default. Once this parameter is set as ``Y``, DAMON_LRU_SORT
37 * reads values of parametrs except ``enabled`` again. Once the re-reading is
38 * done, this parameter is set as ``N``. If invalid parameters are found while
39 * the re-reading, DAMON_LRU_SORT will be disabled.
40 */
41 static bool commit_inputs __read_mostly;
42 module_param(commit_inputs, bool, 0600);
43
44 /*
45 * Access frequency threshold for hot memory regions identification in permil.
46 *
47 * If a memory region is accessed in frequency of this or higher,
48 * DAMON_LRU_SORT identifies the region as hot, and mark it as accessed on the
49 * LRU list, so that it could not be reclaimed under memory pressure. 50% by
50 * default.
51 */
52 static unsigned long hot_thres_access_freq = 500;
53 module_param(hot_thres_access_freq, ulong, 0600);
54
55 /*
56 * Time threshold for cold memory regions identification in microseconds.
57 *
58 * If a memory region is not accessed for this or longer time, DAMON_LRU_SORT
59 * identifies the region as cold, and mark it as unaccessed on the LRU list, so
60 * that it could be reclaimed first under memory pressure. 120 seconds by
61 * default.
62 */
63 static unsigned long cold_min_age __read_mostly = 120000000;
64 module_param(cold_min_age, ulong, 0600);
65
66 static struct damos_quota damon_lru_sort_quota = {
67 /* Use up to 10 ms per 1 sec, by default */
68 .ms = 10,
69 .sz = 0,
70 .reset_interval = 1000,
71 /* Within the quota, mark hotter regions accessed first. */
72 .weight_sz = 0,
73 .weight_nr_accesses = 1,
74 .weight_age = 0,
75 };
76 DEFINE_DAMON_MODULES_DAMOS_TIME_QUOTA(damon_lru_sort_quota);
77
78 static struct damos_watermarks damon_lru_sort_wmarks = {
79 .metric = DAMOS_WMARK_FREE_MEM_RATE,
80 .interval = 5000000, /* 5 seconds */
81 .high = 200, /* 20 percent */
82 .mid = 150, /* 15 percent */
83 .low = 50, /* 5 percent */
84 };
85 DEFINE_DAMON_MODULES_WMARKS_PARAMS(damon_lru_sort_wmarks);
86
87 static struct damon_attrs damon_lru_sort_mon_attrs = {
88 .sample_interval = 5000, /* 5 ms */
89 .aggr_interval = 100000, /* 100 ms */
90 .ops_update_interval = 0,
91 .min_nr_regions = 10,
92 .max_nr_regions = 1000,
93 };
94 DEFINE_DAMON_MODULES_MON_ATTRS_PARAMS(damon_lru_sort_mon_attrs);
95
96 /*
97 * Start of the target memory region in physical address.
98 *
99 * The start physical address of memory region that DAMON_LRU_SORT will do work
100 * against. By default, biggest System RAM is used as the region.
101 */
102 static unsigned long monitor_region_start __read_mostly;
103 module_param(monitor_region_start, ulong, 0600);
104
105 /*
106 * End of the target memory region in physical address.
107 *
108 * The end physical address of memory region that DAMON_LRU_SORT will do work
109 * against. By default, biggest System RAM is used as the region.
110 */
111 static unsigned long monitor_region_end __read_mostly;
112 module_param(monitor_region_end, ulong, 0600);
113
114 /*
115 * PID of the DAMON thread
116 *
117 * If DAMON_LRU_SORT is enabled, this becomes the PID of the worker thread.
118 * Else, -1.
119 */
120 static int kdamond_pid __read_mostly = -1;
121 module_param(kdamond_pid, int, 0400);
122
123 static struct damos_stat damon_lru_sort_hot_stat;
124 DEFINE_DAMON_MODULES_DAMOS_STATS_PARAMS(damon_lru_sort_hot_stat,
125 lru_sort_tried_hot_regions, lru_sorted_hot_regions,
126 hot_quota_exceeds);
127
128 static struct damos_stat damon_lru_sort_cold_stat;
129 DEFINE_DAMON_MODULES_DAMOS_STATS_PARAMS(damon_lru_sort_cold_stat,
130 lru_sort_tried_cold_regions, lru_sorted_cold_regions,
131 cold_quota_exceeds);
132
133 static struct damos_access_pattern damon_lru_sort_stub_pattern = {
134 /* Find regions having PAGE_SIZE or larger size */
135 .min_sz_region = PAGE_SIZE,
136 .max_sz_region = ULONG_MAX,
137 /* no matter its access frequency */
138 .min_nr_accesses = 0,
139 .max_nr_accesses = UINT_MAX,
140 /* no matter its age */
141 .min_age_region = 0,
142 .max_age_region = UINT_MAX,
143 };
144
145 static struct damon_ctx *ctx;
146 static struct damon_target *target;
147
148 static struct damos *damon_lru_sort_new_scheme(
149 struct damos_access_pattern *pattern, enum damos_action action)
150 {
151 struct damos_quota quota = damon_lru_sort_quota;
152
153 /* Use half of total quota for hot/cold pages sorting */
154 quota.ms = quota.ms / 2;
155
156 return damon_new_scheme(
157 /* find the pattern, and */
158 pattern,
159 /* (de)prioritize on LRU-lists */
160 action,
161 /* for each aggregation interval */
162 0,
163 /* under the quota. */
164 "a,
165 /* (De)activate this according to the watermarks. */
166 &damon_lru_sort_wmarks,
167 NUMA_NO_NODE);
168 }
169
170 /* Create a DAMON-based operation scheme for hot memory regions */
171 static struct damos *damon_lru_sort_new_hot_scheme(unsigned int hot_thres)
172 {
173 struct damos_access_pattern pattern = damon_lru_sort_stub_pattern;
174
175 pattern.min_nr_accesses = hot_thres;
176 return damon_lru_sort_new_scheme(&pattern, DAMOS_LRU_PRIO);
177 }
178
179 /* Create a DAMON-based operation scheme for cold memory regions */
180 static struct damos *damon_lru_sort_new_cold_scheme(unsigned int cold_thres)
181 {
182 struct damos_access_pattern pattern = damon_lru_sort_stub_pattern;
183
184 pattern.max_nr_accesses = 0;
185 pattern.min_age_region = cold_thres;
186 return damon_lru_sort_new_scheme(&pattern, DAMOS_LRU_DEPRIO);
187 }
188
189 static int damon_lru_sort_apply_parameters(void)
190 {
191 struct damon_ctx *param_ctx;
192 struct damon_target *param_target;
193 struct damos *hot_scheme, *cold_scheme;
194 unsigned int hot_thres, cold_thres;
195 int err;
196
197 err = damon_modules_new_paddr_ctx_target(¶m_ctx, ¶m_target);
198 if (err)
199 return err;
200
201 err = damon_set_attrs(ctx, &damon_lru_sort_mon_attrs);
202 if (err)
203 goto out;
204
205 err = -ENOMEM;
206 hot_thres = damon_max_nr_accesses(&damon_lru_sort_mon_attrs) *
207 hot_thres_access_freq / 1000;
208 hot_scheme = damon_lru_sort_new_hot_scheme(hot_thres);
209 if (!hot_scheme)
210 goto out;
211
212 cold_thres = cold_min_age / damon_lru_sort_mon_attrs.aggr_interval;
213 cold_scheme = damon_lru_sort_new_cold_scheme(cold_thres);
214 if (!cold_scheme) {
215 damon_destroy_scheme(hot_scheme);
216 goto out;
217 }
218
219 damon_set_schemes(param_ctx, &hot_scheme, 1);
220 damon_add_scheme(param_ctx, cold_scheme);
221
222 err = damon_set_region_biggest_system_ram_default(param_target,
223 &monitor_region_start,
224 &monitor_region_end);
225 if (err)
226 goto out;
227 err = damon_commit_ctx(ctx, param_ctx);
228 out:
229 damon_destroy_ctx(param_ctx);
230 return err;
231 }
232
233 static int damon_lru_sort_turn(bool on)
234 {
235 int err;
236
237 if (!on) {
238 err = damon_stop(&ctx, 1);
239 if (!err)
240 kdamond_pid = -1;
241 return err;
242 }
243
244 err = damon_lru_sort_apply_parameters();
245 if (err)
246 return err;
247
248 err = damon_start(&ctx, 1, true);
249 if (err)
250 return err;
251 kdamond_pid = ctx->kdamond->pid;
252 return 0;
253 }
254
255 static int damon_lru_sort_enabled_store(const char *val,
256 const struct kernel_param *kp)
257 {
258 bool is_enabled = enabled;
259 bool enable;
260 int err;
261
262 err = kstrtobool(val, &enable);
263 if (err)
264 return err;
265
266 if (is_enabled == enable)
267 return 0;
268
269 /* Called before init function. The function will handle this. */
270 if (!ctx)
271 goto set_param_out;
272
273 err = damon_lru_sort_turn(enable);
274 if (err)
275 return err;
276
277 set_param_out:
278 enabled = enable;
279 return err;
280 }
281
282 static const struct kernel_param_ops enabled_param_ops = {
283 .set = damon_lru_sort_enabled_store,
284 .get = param_get_bool,
285 };
286
287 module_param_cb(enabled, &enabled_param_ops, &enabled, 0600);
288 MODULE_PARM_DESC(enabled,
289 "Enable or disable DAMON_LRU_SORT (default: disabled)");
290
291 static int damon_lru_sort_handle_commit_inputs(void)
292 {
293 int err;
294
295 if (!commit_inputs)
296 return 0;
297
298 err = damon_lru_sort_apply_parameters();
299 commit_inputs = false;
300 return err;
301 }
302
303 static int damon_lru_sort_after_aggregation(struct damon_ctx *c)
304 {
305 struct damos *s;
306
307 /* update the stats parameter */
308 damon_for_each_scheme(s, c) {
309 if (s->action == DAMOS_LRU_PRIO)
310 damon_lru_sort_hot_stat = s->stat;
311 else if (s->action == DAMOS_LRU_DEPRIO)
312 damon_lru_sort_cold_stat = s->stat;
313 }
314
315 return damon_lru_sort_handle_commit_inputs();
316 }
317
318 static int damon_lru_sort_after_wmarks_check(struct damon_ctx *c)
319 {
320 return damon_lru_sort_handle_commit_inputs();
321 }
322
323 static int __init damon_lru_sort_init(void)
324 {
325 int err = damon_modules_new_paddr_ctx_target(&ctx, &target);
326
327 if (err)
328 return err;
329
330 ctx->callback.after_wmarks_check = damon_lru_sort_after_wmarks_check;
331 ctx->callback.after_aggregation = damon_lru_sort_after_aggregation;
332
333 /* 'enabled' has set before this function, probably via command line */
334 if (enabled)
335 err = damon_lru_sort_turn(true);
336
337 return err;
338 }
339
340 module_init(damon_lru_sort_init);
341
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