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 */
30static 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 */
41static bool commit_inputs __read_mostly;
42module_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 */
50static unsigned long min_age __read_mostly = 120000000;
51module_param(min_age, ulong, 0600);
52
53static 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};
63DEFINE_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 */
77static unsigned long quota_mem_pressure_us __read_mostly;
78module_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 */
92static unsigned long quota_autotune_feedback __read_mostly;
93module_param(quota_autotune_feedback, ulong, 0600);
94
95static 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};
102DEFINE_DAMON_MODULES_WMARKS_PARAMS(damon_reclaim_wmarks);
103
104static 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};
111DEFINE_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 */
119static unsigned long monitor_region_start __read_mostly;
120module_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 */
128static unsigned long monitor_region_end __read_mostly;
129module_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 */
137static bool skip_anon __read_mostly;
138module_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 */
146static int kdamond_pid __read_mostly = -1;
147module_param(kdamond_pid, int, 0400);
148
149static struct damos_stat damon_reclaim_stat;
150DEFINE_DAMON_MODULES_DAMOS_STATS_PARAMS(damon_reclaim_stat,
151 reclaim_tried_regions, reclaimed_regions, quota_exceeds);
152
153static struct damon_ctx *ctx;
154static struct damon_target *target;
155
156static 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: &pattern,
173 /* page out those, as soon as found */
174 action: DAMOS_PAGEOUT,
175 /* for each aggregation interval */
176 apply_interval_us: 0,
177 /* under the quota. */
178 quota: &damon_reclaim_quota,
179 /* (De)activate this according to the watermarks. */
180 wmarks: &damon_reclaim_wmarks);
181}
182
183static void damon_reclaim_copy_quota_status(struct damos_quota *dst,
184 struct damos_quota *src)
185{
186 dst->total_charged_sz = src->total_charged_sz;
187 dst->total_charged_ns = src->total_charged_ns;
188 dst->charged_sz = src->charged_sz;
189 dst->charged_from = src->charged_from;
190 dst->charge_target_from = src->charge_target_from;
191 dst->charge_addr_from = src->charge_addr_from;
192 dst->esz_bp = src->esz_bp;
193}
194
195static int damon_reclaim_apply_parameters(void)
196{
197 struct damos *scheme, *old_scheme;
198 struct damos_quota_goal *goal;
199 struct damos_filter *filter;
200 int err = 0;
201
202 err = damon_set_attrs(ctx, attrs: &damon_reclaim_mon_attrs);
203 if (err)
204 return err;
205
206 /* Will be freed by next 'damon_set_schemes()' below */
207 scheme = damon_reclaim_new_scheme();
208 if (!scheme)
209 return -ENOMEM;
210 if (!list_empty(head: &ctx->schemes)) {
211 damon_for_each_scheme(old_scheme, ctx)
212 damon_reclaim_copy_quota_status(dst: &scheme->quota,
213 src: &old_scheme->quota);
214 }
215
216 if (quota_mem_pressure_us) {
217 goal = damos_new_quota_goal(metric: DAMOS_QUOTA_SOME_MEM_PSI_US,
218 target_value: quota_mem_pressure_us);
219 if (!goal) {
220 damon_destroy_scheme(s: scheme);
221 return -ENOMEM;
222 }
223 damos_add_quota_goal(q: &scheme->quota, g: goal);
224 }
225
226 if (quota_autotune_feedback) {
227 goal = damos_new_quota_goal(metric: DAMOS_QUOTA_USER_INPUT, target_value: 10000);
228 if (!goal) {
229 damon_destroy_scheme(s: scheme);
230 return -ENOMEM;
231 }
232 goal->current_value = quota_autotune_feedback;
233 damos_add_quota_goal(q: &scheme->quota, g: goal);
234 }
235
236 if (skip_anon) {
237 filter = damos_new_filter(type: DAMOS_FILTER_TYPE_ANON, matching: true);
238 if (!filter) {
239 /* Will be freed by next 'damon_set_schemes()' below */
240 damon_destroy_scheme(s: scheme);
241 return -ENOMEM;
242 }
243 damos_add_filter(s: scheme, f: filter);
244 }
245 damon_set_schemes(ctx, schemes: &scheme, nr_schemes: 1);
246
247 return damon_set_region_biggest_system_ram_default(t: target,
248 start: &monitor_region_start,
249 end: &monitor_region_end);
250}
251
252static int damon_reclaim_turn(bool on)
253{
254 int err;
255
256 if (!on) {
257 err = damon_stop(ctxs: &ctx, nr_ctxs: 1);
258 if (!err)
259 kdamond_pid = -1;
260 return err;
261 }
262
263 err = damon_reclaim_apply_parameters();
264 if (err)
265 return err;
266
267 err = damon_start(ctxs: &ctx, nr_ctxs: 1, exclusive: true);
268 if (err)
269 return err;
270 kdamond_pid = ctx->kdamond->pid;
271 return 0;
272}
273
274static int damon_reclaim_enabled_store(const char *val,
275 const struct kernel_param *kp)
276{
277 bool is_enabled = enabled;
278 bool enable;
279 int err;
280
281 err = kstrtobool(s: val, res: &enable);
282 if (err)
283 return err;
284
285 if (is_enabled == enable)
286 return 0;
287
288 /* Called before init function. The function will handle this. */
289 if (!ctx)
290 goto set_param_out;
291
292 err = damon_reclaim_turn(on: enable);
293 if (err)
294 return err;
295
296set_param_out:
297 enabled = enable;
298 return err;
299}
300
301static const struct kernel_param_ops enabled_param_ops = {
302 .set = damon_reclaim_enabled_store,
303 .get = param_get_bool,
304};
305
306module_param_cb(enabled, &enabled_param_ops, &enabled, 0600);
307MODULE_PARM_DESC(enabled,
308 "Enable or disable DAMON_RECLAIM (default: disabled)");
309
310static int damon_reclaim_handle_commit_inputs(void)
311{
312 int err;
313
314 if (!commit_inputs)
315 return 0;
316
317 err = damon_reclaim_apply_parameters();
318 commit_inputs = false;
319 return err;
320}
321
322static int damon_reclaim_after_aggregation(struct damon_ctx *c)
323{
324 struct damos *s;
325
326 /* update the stats parameter */
327 damon_for_each_scheme(s, c)
328 damon_reclaim_stat = s->stat;
329
330 return damon_reclaim_handle_commit_inputs();
331}
332
333static int damon_reclaim_after_wmarks_check(struct damon_ctx *c)
334{
335 return damon_reclaim_handle_commit_inputs();
336}
337
338static int __init damon_reclaim_init(void)
339{
340 int err = damon_modules_new_paddr_ctx_target(ctxp: &ctx, targetp: &target);
341
342 if (err)
343 return err;
344
345 ctx->callback.after_wmarks_check = damon_reclaim_after_wmarks_check;
346 ctx->callback.after_aggregation = damon_reclaim_after_aggregation;
347
348 /* 'enabled' has set before this function, probably via command line */
349 if (enabled)
350 err = damon_reclaim_turn(on: true);
351
352 return err;
353}
354
355module_init(damon_reclaim_init);
356

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