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
damon_lru_sort_new_scheme(struct damos_access_pattern * pattern,enum damos_action action)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 /* under the quota. */
162 "a,
163 /* (De)activate this according to the watermarks. */
164 &damon_lru_sort_wmarks);
165 }
166
167 /* Create a DAMON-based operation scheme for hot memory regions */
damon_lru_sort_new_hot_scheme(unsigned int hot_thres)168 static struct damos *damon_lru_sort_new_hot_scheme(unsigned int hot_thres)
169 {
170 struct damos_access_pattern pattern = damon_lru_sort_stub_pattern;
171
172 pattern.min_nr_accesses = hot_thres;
173 return damon_lru_sort_new_scheme(&pattern, DAMOS_LRU_PRIO);
174 }
175
176 /* Create a DAMON-based operation scheme for cold memory regions */
damon_lru_sort_new_cold_scheme(unsigned int cold_thres)177 static struct damos *damon_lru_sort_new_cold_scheme(unsigned int cold_thres)
178 {
179 struct damos_access_pattern pattern = damon_lru_sort_stub_pattern;
180
181 pattern.max_nr_accesses = 0;
182 pattern.min_age_region = cold_thres;
183 return damon_lru_sort_new_scheme(&pattern, DAMOS_LRU_DEPRIO);
184 }
185
damon_lru_sort_copy_quota_status(struct damos_quota * dst,struct damos_quota * src)186 static void damon_lru_sort_copy_quota_status(struct damos_quota *dst,
187 struct damos_quota *src)
188 {
189 dst->total_charged_sz = src->total_charged_sz;
190 dst->total_charged_ns = src->total_charged_ns;
191 dst->charged_sz = src->charged_sz;
192 dst->charged_from = src->charged_from;
193 dst->charge_target_from = src->charge_target_from;
194 dst->charge_addr_from = src->charge_addr_from;
195 }
196
damon_lru_sort_apply_parameters(void)197 static int damon_lru_sort_apply_parameters(void)
198 {
199 struct damos *scheme, *hot_scheme, *cold_scheme;
200 struct damos *old_hot_scheme = NULL, *old_cold_scheme = NULL;
201 unsigned int hot_thres, cold_thres;
202 int err = 0;
203
204 err = damon_set_attrs(ctx, &damon_lru_sort_mon_attrs);
205 if (err)
206 return err;
207
208 damon_for_each_scheme(scheme, ctx) {
209 if (!old_hot_scheme) {
210 old_hot_scheme = scheme;
211 continue;
212 }
213 old_cold_scheme = scheme;
214 }
215
216 hot_thres = damon_max_nr_accesses(&damon_lru_sort_mon_attrs) *
217 hot_thres_access_freq / 1000;
218 hot_scheme = damon_lru_sort_new_hot_scheme(hot_thres);
219 if (!hot_scheme)
220 return -ENOMEM;
221 if (old_hot_scheme)
222 damon_lru_sort_copy_quota_status(&hot_scheme->quota,
223 &old_hot_scheme->quota);
224
225 cold_thres = cold_min_age / damon_lru_sort_mon_attrs.aggr_interval;
226 cold_scheme = damon_lru_sort_new_cold_scheme(cold_thres);
227 if (!cold_scheme) {
228 damon_destroy_scheme(hot_scheme);
229 return -ENOMEM;
230 }
231 if (old_cold_scheme)
232 damon_lru_sort_copy_quota_status(&cold_scheme->quota,
233 &old_cold_scheme->quota);
234
235 damon_set_schemes(ctx, &hot_scheme, 1);
236 damon_add_scheme(ctx, cold_scheme);
237
238 return damon_set_region_biggest_system_ram_default(target,
239 &monitor_region_start,
240 &monitor_region_end);
241 }
242
damon_lru_sort_turn(bool on)243 static int damon_lru_sort_turn(bool on)
244 {
245 int err;
246
247 if (!on) {
248 err = damon_stop(&ctx, 1);
249 if (!err)
250 kdamond_pid = -1;
251 return err;
252 }
253
254 err = damon_lru_sort_apply_parameters();
255 if (err)
256 return err;
257
258 err = damon_start(&ctx, 1, true);
259 if (err)
260 return err;
261 kdamond_pid = ctx->kdamond->pid;
262 return 0;
263 }
264
damon_lru_sort_enabled_store(const char * val,const struct kernel_param * kp)265 static int damon_lru_sort_enabled_store(const char *val,
266 const struct kernel_param *kp)
267 {
268 bool is_enabled = enabled;
269 bool enable;
270 int err;
271
272 err = kstrtobool(val, &enable);
273 if (err)
274 return err;
275
276 if (is_enabled == enable)
277 return 0;
278
279 /* Called before init function. The function will handle this. */
280 if (!ctx)
281 goto set_param_out;
282
283 err = damon_lru_sort_turn(enable);
284 if (err)
285 return err;
286
287 set_param_out:
288 enabled = enable;
289 return err;
290 }
291
292 static const struct kernel_param_ops enabled_param_ops = {
293 .set = damon_lru_sort_enabled_store,
294 .get = param_get_bool,
295 };
296
297 module_param_cb(enabled, &enabled_param_ops, &enabled, 0600);
298 MODULE_PARM_DESC(enabled,
299 "Enable or disable DAMON_LRU_SORT (default: disabled)");
300
damon_lru_sort_handle_commit_inputs(void)301 static int damon_lru_sort_handle_commit_inputs(void)
302 {
303 int err;
304
305 if (!commit_inputs)
306 return 0;
307
308 err = damon_lru_sort_apply_parameters();
309 commit_inputs = false;
310 return err;
311 }
312
damon_lru_sort_after_aggregation(struct damon_ctx * c)313 static int damon_lru_sort_after_aggregation(struct damon_ctx *c)
314 {
315 struct damos *s;
316
317 /* update the stats parameter */
318 damon_for_each_scheme(s, c) {
319 if (s->action == DAMOS_LRU_PRIO)
320 damon_lru_sort_hot_stat = s->stat;
321 else if (s->action == DAMOS_LRU_DEPRIO)
322 damon_lru_sort_cold_stat = s->stat;
323 }
324
325 return damon_lru_sort_handle_commit_inputs();
326 }
327
damon_lru_sort_after_wmarks_check(struct damon_ctx * c)328 static int damon_lru_sort_after_wmarks_check(struct damon_ctx *c)
329 {
330 return damon_lru_sort_handle_commit_inputs();
331 }
332
damon_lru_sort_init(void)333 static int __init damon_lru_sort_init(void)
334 {
335 int err = damon_modules_new_paddr_ctx_target(&ctx, &target);
336
337 if (err)
338 return err;
339
340 ctx->callback.after_wmarks_check = damon_lru_sort_after_wmarks_check;
341 ctx->callback.after_aggregation = damon_lru_sort_after_aggregation;
342
343 /* 'enabled' has set before this function, probably via command line */
344 if (enabled)
345 err = damon_lru_sort_turn(true);
346
347 return err;
348 }
349
350 module_init(damon_lru_sort_init);
351