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 * Scale factor for DAMON_LRU_SORT to ops address conversion.
116 *
117 * This parameter must not be set to 0.
118 */
119static unsigned long addr_unit __read_mostly = 1;
120
121/*
122 * PID of the DAMON thread
123 *
124 * If DAMON_LRU_SORT is enabled, this becomes the PID of the worker thread.
125 * Else, -1.
126 */
127static int kdamond_pid __read_mostly = -1;
128module_param(kdamond_pid, int, 0400);
129
130static struct damos_stat damon_lru_sort_hot_stat;
131DEFINE_DAMON_MODULES_DAMOS_STATS_PARAMS(damon_lru_sort_hot_stat,
132 lru_sort_tried_hot_regions, lru_sorted_hot_regions,
133 hot_quota_exceeds);
134
135static struct damos_stat damon_lru_sort_cold_stat;
136DEFINE_DAMON_MODULES_DAMOS_STATS_PARAMS(damon_lru_sort_cold_stat,
137 lru_sort_tried_cold_regions, lru_sorted_cold_regions,
138 cold_quota_exceeds);
139
140static struct damos_access_pattern damon_lru_sort_stub_pattern = {
141 /* Find regions having PAGE_SIZE or larger size */
142 .min_sz_region = PAGE_SIZE,
143 .max_sz_region = ULONG_MAX,
144 /* no matter its access frequency */
145 .min_nr_accesses = 0,
146 .max_nr_accesses = UINT_MAX,
147 /* no matter its age */
148 .min_age_region = 0,
149 .max_age_region = UINT_MAX,
150};
151
152static struct damon_ctx *ctx;
153static struct damon_target *target;
154
155static struct damos *damon_lru_sort_new_scheme(
156 struct damos_access_pattern *pattern, enum damos_action action)
157{
158 struct damos_quota quota = damon_lru_sort_quota;
159
160 /* Use half of total quota for hot/cold pages sorting */
161 quota.ms = quota.ms / 2;
162
163 return damon_new_scheme(
164 /* find the pattern, and */
165 pattern,
166 /* (de)prioritize on LRU-lists */
167 action,
168 /* for each aggregation interval */
169 apply_interval_us: 0,
170 /* under the quota. */
171 quota: &quota,
172 /* (De)activate this according to the watermarks. */
173 wmarks: &damon_lru_sort_wmarks,
174 NUMA_NO_NODE);
175}
176
177/* Create a DAMON-based operation scheme for hot memory regions */
178static struct damos *damon_lru_sort_new_hot_scheme(unsigned int hot_thres)
179{
180 struct damos_access_pattern pattern = damon_lru_sort_stub_pattern;
181
182 pattern.min_nr_accesses = hot_thres;
183 return damon_lru_sort_new_scheme(pattern: &pattern, action: DAMOS_LRU_PRIO);
184}
185
186/* Create a DAMON-based operation scheme for cold memory regions */
187static struct damos *damon_lru_sort_new_cold_scheme(unsigned int cold_thres)
188{
189 struct damos_access_pattern pattern = damon_lru_sort_stub_pattern;
190
191 pattern.max_nr_accesses = 0;
192 pattern.min_age_region = cold_thres;
193 return damon_lru_sort_new_scheme(pattern: &pattern, action: DAMOS_LRU_DEPRIO);
194}
195
196static int damon_lru_sort_apply_parameters(void)
197{
198 struct damon_ctx *param_ctx;
199 struct damon_target *param_target;
200 struct damos *hot_scheme, *cold_scheme;
201 unsigned int hot_thres, cold_thres;
202 int err;
203
204 err = damon_modules_new_paddr_ctx_target(ctxp: &param_ctx, targetp: &param_target);
205 if (err)
206 return err;
207
208 /*
209 * If monitor_region_start/end are unset, always silently
210 * reset addr_unit to 1.
211 */
212 if (!monitor_region_start && !monitor_region_end)
213 addr_unit = 1;
214 param_ctx->addr_unit = addr_unit;
215 param_ctx->min_sz_region = max(DAMON_MIN_REGION / addr_unit, 1);
216
217 if (!damon_lru_sort_mon_attrs.sample_interval) {
218 err = -EINVAL;
219 goto out;
220 }
221
222 err = damon_set_attrs(ctx: param_ctx, attrs: &damon_lru_sort_mon_attrs);
223 if (err)
224 goto out;
225
226 err = -ENOMEM;
227 hot_thres = damon_max_nr_accesses(attrs: &damon_lru_sort_mon_attrs) *
228 hot_thres_access_freq / 1000;
229 hot_scheme = damon_lru_sort_new_hot_scheme(hot_thres);
230 if (!hot_scheme)
231 goto out;
232
233 cold_thres = cold_min_age / damon_lru_sort_mon_attrs.aggr_interval;
234 cold_scheme = damon_lru_sort_new_cold_scheme(cold_thres);
235 if (!cold_scheme) {
236 damon_destroy_scheme(s: hot_scheme);
237 goto out;
238 }
239
240 damon_set_schemes(ctx: param_ctx, schemes: &hot_scheme, nr_schemes: 1);
241 damon_add_scheme(ctx: param_ctx, s: cold_scheme);
242
243 err = damon_set_region_biggest_system_ram_default(t: param_target,
244 start: &monitor_region_start,
245 end: &monitor_region_end,
246 min_sz_region: param_ctx->min_sz_region);
247 if (err)
248 goto out;
249 err = damon_commit_ctx(old_ctx: ctx, new_ctx: param_ctx);
250out:
251 damon_destroy_ctx(ctx: param_ctx);
252 return err;
253}
254
255static int damon_lru_sort_handle_commit_inputs(void)
256{
257 int err;
258
259 if (!commit_inputs)
260 return 0;
261
262 err = damon_lru_sort_apply_parameters();
263 commit_inputs = false;
264 return err;
265}
266
267static int damon_lru_sort_damon_call_fn(void *arg)
268{
269 struct damon_ctx *c = arg;
270 struct damos *s;
271
272 /* update the stats parameter */
273 damon_for_each_scheme(s, c) {
274 if (s->action == DAMOS_LRU_PRIO)
275 damon_lru_sort_hot_stat = s->stat;
276 else if (s->action == DAMOS_LRU_DEPRIO)
277 damon_lru_sort_cold_stat = s->stat;
278 }
279
280 return damon_lru_sort_handle_commit_inputs();
281}
282
283static struct damon_call_control call_control = {
284 .fn = damon_lru_sort_damon_call_fn,
285 .repeat = true,
286};
287
288static int damon_lru_sort_turn(bool on)
289{
290 int err;
291
292 if (!on) {
293 err = damon_stop(ctxs: &ctx, nr_ctxs: 1);
294 if (!err)
295 kdamond_pid = -1;
296 return err;
297 }
298
299 err = damon_lru_sort_apply_parameters();
300 if (err)
301 return err;
302
303 err = damon_start(ctxs: &ctx, nr_ctxs: 1, exclusive: true);
304 if (err)
305 return err;
306 kdamond_pid = ctx->kdamond->pid;
307 return damon_call(ctx, control: &call_control);
308}
309
310static int damon_lru_sort_addr_unit_store(const char *val,
311 const struct kernel_param *kp)
312{
313 unsigned long input_addr_unit;
314 int err = kstrtoul(s: val, base: 0, res: &input_addr_unit);
315
316 if (err)
317 return err;
318 if (!input_addr_unit)
319 return -EINVAL;
320
321 addr_unit = input_addr_unit;
322 return 0;
323}
324
325static const struct kernel_param_ops addr_unit_param_ops = {
326 .set = damon_lru_sort_addr_unit_store,
327 .get = param_get_ulong,
328};
329
330module_param_cb(addr_unit, &addr_unit_param_ops, &addr_unit, 0600);
331MODULE_PARM_DESC(addr_unit,
332 "Scale factor for DAMON_LRU_SORT to ops address conversion (default: 1)");
333
334static int damon_lru_sort_enabled_store(const char *val,
335 const struct kernel_param *kp)
336{
337 bool is_enabled = enabled;
338 bool enable;
339 int err;
340
341 err = kstrtobool(s: val, res: &enable);
342 if (err)
343 return err;
344
345 if (is_enabled == enable)
346 return 0;
347
348 /* Called before init function. The function will handle this. */
349 if (!damon_initialized())
350 goto set_param_out;
351
352 err = damon_lru_sort_turn(on: enable);
353 if (err)
354 return err;
355
356set_param_out:
357 enabled = enable;
358 return err;
359}
360
361static const struct kernel_param_ops enabled_param_ops = {
362 .set = damon_lru_sort_enabled_store,
363 .get = param_get_bool,
364};
365
366module_param_cb(enabled, &enabled_param_ops, &enabled, 0600);
367MODULE_PARM_DESC(enabled,
368 "Enable or disable DAMON_LRU_SORT (default: disabled)");
369
370static int __init damon_lru_sort_init(void)
371{
372 int err;
373
374 if (!damon_initialized()) {
375 err = -ENOMEM;
376 goto out;
377 }
378 err = damon_modules_new_paddr_ctx_target(ctxp: &ctx, targetp: &target);
379 if (err)
380 goto out;
381
382 call_control.data = ctx;
383
384 /* 'enabled' has set before this function, probably via command line */
385 if (enabled)
386 err = damon_lru_sort_turn(on: true);
387
388out:
389 if (err && enabled)
390 enabled = false;
391 return err;
392}
393
394module_init(damon_lru_sort_init);
395

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