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 */
30static 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 */
41static bool commit_inputs __read_mostly;
42module_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 */
52static unsigned long hot_thres_access_freq = 500;
53module_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 */
63static unsigned long cold_min_age __read_mostly = 120000000;
64module_param(cold_min_age, ulong, 0600);
65
66static 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};
76DEFINE_DAMON_MODULES_DAMOS_TIME_QUOTA(damon_lru_sort_quota);
77
78static 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};
85DEFINE_DAMON_MODULES_WMARKS_PARAMS(damon_lru_sort_wmarks);
86
87static 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};
94DEFINE_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 */
102static unsigned long monitor_region_start __read_mostly;
103module_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 */
111static unsigned long monitor_region_end __read_mostly;
112module_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 */
120static int kdamond_pid __read_mostly = -1;
121module_param(kdamond_pid, int, 0400);
122
123static struct damos_stat damon_lru_sort_hot_stat;
124DEFINE_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
128static struct damos_stat damon_lru_sort_cold_stat;
129DEFINE_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
133static 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
145static struct damon_ctx *ctx;
146static struct damon_target *target;
147
148static 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 apply_interval_us: 0,
163 /* under the quota. */
164 quota: &quota,
165 /* (De)activate this according to the watermarks. */
166 wmarks: &damon_lru_sort_wmarks);
167}
168
169/* Create a DAMON-based operation scheme for hot memory regions */
170static struct damos *damon_lru_sort_new_hot_scheme(unsigned int hot_thres)
171{
172 struct damos_access_pattern pattern = damon_lru_sort_stub_pattern;
173
174 pattern.min_nr_accesses = hot_thres;
175 return damon_lru_sort_new_scheme(pattern: &pattern, action: DAMOS_LRU_PRIO);
176}
177
178/* Create a DAMON-based operation scheme for cold memory regions */
179static struct damos *damon_lru_sort_new_cold_scheme(unsigned int cold_thres)
180{
181 struct damos_access_pattern pattern = damon_lru_sort_stub_pattern;
182
183 pattern.max_nr_accesses = 0;
184 pattern.min_age_region = cold_thres;
185 return damon_lru_sort_new_scheme(pattern: &pattern, action: DAMOS_LRU_DEPRIO);
186}
187
188static void damon_lru_sort_copy_quota_status(struct damos_quota *dst,
189 struct damos_quota *src)
190{
191 dst->total_charged_sz = src->total_charged_sz;
192 dst->total_charged_ns = src->total_charged_ns;
193 dst->charged_sz = src->charged_sz;
194 dst->charged_from = src->charged_from;
195 dst->charge_target_from = src->charge_target_from;
196 dst->charge_addr_from = src->charge_addr_from;
197}
198
199static int damon_lru_sort_apply_parameters(void)
200{
201 struct damos *scheme, *hot_scheme, *cold_scheme;
202 struct damos *old_hot_scheme = NULL, *old_cold_scheme = NULL;
203 unsigned int hot_thres, cold_thres;
204 int err = 0;
205
206 err = damon_set_attrs(ctx, attrs: &damon_lru_sort_mon_attrs);
207 if (err)
208 return err;
209
210 damon_for_each_scheme(scheme, ctx) {
211 if (!old_hot_scheme) {
212 old_hot_scheme = scheme;
213 continue;
214 }
215 old_cold_scheme = scheme;
216 }
217
218 hot_thres = damon_max_nr_accesses(attrs: &damon_lru_sort_mon_attrs) *
219 hot_thres_access_freq / 1000;
220 hot_scheme = damon_lru_sort_new_hot_scheme(hot_thres);
221 if (!hot_scheme)
222 return -ENOMEM;
223 if (old_hot_scheme)
224 damon_lru_sort_copy_quota_status(dst: &hot_scheme->quota,
225 src: &old_hot_scheme->quota);
226
227 cold_thres = cold_min_age / damon_lru_sort_mon_attrs.aggr_interval;
228 cold_scheme = damon_lru_sort_new_cold_scheme(cold_thres);
229 if (!cold_scheme) {
230 damon_destroy_scheme(s: hot_scheme);
231 return -ENOMEM;
232 }
233 if (old_cold_scheme)
234 damon_lru_sort_copy_quota_status(dst: &cold_scheme->quota,
235 src: &old_cold_scheme->quota);
236
237 damon_set_schemes(ctx, schemes: &hot_scheme, nr_schemes: 1);
238 damon_add_scheme(ctx, s: cold_scheme);
239
240 return damon_set_region_biggest_system_ram_default(t: target,
241 start: &monitor_region_start,
242 end: &monitor_region_end);
243}
244
245static int damon_lru_sort_turn(bool on)
246{
247 int err;
248
249 if (!on) {
250 err = damon_stop(ctxs: &ctx, nr_ctxs: 1);
251 if (!err)
252 kdamond_pid = -1;
253 return err;
254 }
255
256 err = damon_lru_sort_apply_parameters();
257 if (err)
258 return err;
259
260 err = damon_start(ctxs: &ctx, nr_ctxs: 1, exclusive: true);
261 if (err)
262 return err;
263 kdamond_pid = ctx->kdamond->pid;
264 return 0;
265}
266
267static int damon_lru_sort_enabled_store(const char *val,
268 const struct kernel_param *kp)
269{
270 bool is_enabled = enabled;
271 bool enable;
272 int err;
273
274 err = kstrtobool(s: val, res: &enable);
275 if (err)
276 return err;
277
278 if (is_enabled == enable)
279 return 0;
280
281 /* Called before init function. The function will handle this. */
282 if (!ctx)
283 goto set_param_out;
284
285 err = damon_lru_sort_turn(on: enable);
286 if (err)
287 return err;
288
289set_param_out:
290 enabled = enable;
291 return err;
292}
293
294static const struct kernel_param_ops enabled_param_ops = {
295 .set = damon_lru_sort_enabled_store,
296 .get = param_get_bool,
297};
298
299module_param_cb(enabled, &enabled_param_ops, &enabled, 0600);
300MODULE_PARM_DESC(enabled,
301 "Enable or disable DAMON_LRU_SORT (default: disabled)");
302
303static int damon_lru_sort_handle_commit_inputs(void)
304{
305 int err;
306
307 if (!commit_inputs)
308 return 0;
309
310 err = damon_lru_sort_apply_parameters();
311 commit_inputs = false;
312 return err;
313}
314
315static int damon_lru_sort_after_aggregation(struct damon_ctx *c)
316{
317 struct damos *s;
318
319 /* update the stats parameter */
320 damon_for_each_scheme(s, c) {
321 if (s->action == DAMOS_LRU_PRIO)
322 damon_lru_sort_hot_stat = s->stat;
323 else if (s->action == DAMOS_LRU_DEPRIO)
324 damon_lru_sort_cold_stat = s->stat;
325 }
326
327 return damon_lru_sort_handle_commit_inputs();
328}
329
330static int damon_lru_sort_after_wmarks_check(struct damon_ctx *c)
331{
332 return damon_lru_sort_handle_commit_inputs();
333}
334
335static int __init damon_lru_sort_init(void)
336{
337 int err = damon_modules_new_paddr_ctx_target(ctxp: &ctx, targetp: &target);
338
339 if (err)
340 return err;
341
342 ctx->callback.after_wmarks_check = damon_lru_sort_after_wmarks_check;
343 ctx->callback.after_aggregation = damon_lru_sort_after_aggregation;
344
345 /* 'enabled' has set before this function, probably via command line */
346 if (enabled)
347 err = damon_lru_sort_turn(on: true);
348
349 return err;
350}
351
352module_init(damon_lru_sort_init);
353

source code of linux/mm/damon/lru_sort.c