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 */
30 static 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 */
41 static bool commit_inputs __read_mostly;
42 module_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 */
50 static unsigned long min_age __read_mostly = 120000000;
51 module_param(min_age, ulong, 0600);
52
53 static 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 };
63 DEFINE_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 */
77 static unsigned long quota_mem_pressure_us __read_mostly;
78 module_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 */
92 static unsigned long quota_autotune_feedback __read_mostly;
93 module_param(quota_autotune_feedback, ulong, 0600);
94
95 static 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 };
102 DEFINE_DAMON_MODULES_WMARKS_PARAMS(damon_reclaim_wmarks);
103
104 static 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 };
111 DEFINE_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 */
119 static unsigned long monitor_region_start __read_mostly;
120 module_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 */
128 static unsigned long monitor_region_end __read_mostly;
129 module_param(monitor_region_end, ulong, 0600);
130
131 /*
132 * Scale factor for DAMON_RECLAIM to ops address conversion.
133 *
134 * This parameter must not be set to 0.
135 */
136 static unsigned long addr_unit __read_mostly = 1;
137
138 /*
139 * Skip anonymous pages reclamation.
140 *
141 * If this parameter is set as ``Y``, DAMON_RECLAIM does not reclaim anonymous
142 * pages. By default, ``N``.
143 */
144 static bool skip_anon __read_mostly;
145 module_param(skip_anon, bool, 0600);
146
147 /*
148 * PID of the DAMON thread
149 *
150 * If DAMON_RECLAIM is enabled, this becomes the PID of the worker thread.
151 * Else, -1.
152 */
153 static int kdamond_pid __read_mostly = -1;
154 module_param(kdamond_pid, int, 0400);
155
156 static struct damos_stat damon_reclaim_stat;
157 DEFINE_DAMON_MODULES_DAMOS_STATS_PARAMS(damon_reclaim_stat,
158 reclaim_tried_regions, reclaimed_regions, quota_exceeds);
159
160 static struct damon_ctx *ctx;
161 static struct damon_target *target;
162
damon_reclaim_new_scheme(void)163 static struct damos *damon_reclaim_new_scheme(void)
164 {
165 struct damos_access_pattern pattern = {
166 /* Find regions having PAGE_SIZE or larger size */
167 .min_sz_region = PAGE_SIZE,
168 .max_sz_region = ULONG_MAX,
169 /* and not accessed at all */
170 .min_nr_accesses = 0,
171 .max_nr_accesses = 0,
172 /* for min_age or more micro-seconds */
173 .min_age_region = min_age /
174 damon_reclaim_mon_attrs.aggr_interval,
175 .max_age_region = UINT_MAX,
176 };
177
178 return damon_new_scheme(
179 &pattern,
180 /* page out those, as soon as found */
181 DAMOS_PAGEOUT,
182 /* for each aggregation interval */
183 0,
184 /* under the quota. */
185 &damon_reclaim_quota,
186 /* (De)activate this according to the watermarks. */
187 &damon_reclaim_wmarks,
188 NUMA_NO_NODE);
189 }
190
damon_reclaim_apply_parameters(void)191 static int damon_reclaim_apply_parameters(void)
192 {
193 struct damon_ctx *param_ctx;
194 struct damon_target *param_target;
195 struct damos *scheme;
196 struct damos_quota_goal *goal;
197 struct damos_filter *filter;
198 int err;
199
200 err = damon_modules_new_paddr_ctx_target(¶m_ctx, ¶m_target);
201 if (err)
202 return err;
203
204 /*
205 * If monitor_region_start/end are unset, always silently
206 * reset addr_unit to 1.
207 */
208 if (!monitor_region_start && !monitor_region_end)
209 addr_unit = 1;
210 param_ctx->addr_unit = addr_unit;
211 param_ctx->min_sz_region = max(DAMON_MIN_REGION / addr_unit, 1);
212
213 if (!damon_reclaim_mon_attrs.aggr_interval) {
214 err = -EINVAL;
215 goto out;
216 }
217
218 err = damon_set_attrs(param_ctx, &damon_reclaim_mon_attrs);
219 if (err)
220 goto out;
221
222 err = -ENOMEM;
223 scheme = damon_reclaim_new_scheme();
224 if (!scheme)
225 goto out;
226 damon_set_schemes(param_ctx, &scheme, 1);
227
228 if (quota_mem_pressure_us) {
229 goal = damos_new_quota_goal(DAMOS_QUOTA_SOME_MEM_PSI_US,
230 quota_mem_pressure_us);
231 if (!goal)
232 goto out;
233 damos_add_quota_goal(&scheme->quota, goal);
234 }
235
236 if (quota_autotune_feedback) {
237 goal = damos_new_quota_goal(DAMOS_QUOTA_USER_INPUT, 10000);
238 if (!goal)
239 goto out;
240 goal->current_value = quota_autotune_feedback;
241 damos_add_quota_goal(&scheme->quota, goal);
242 }
243
244 if (skip_anon) {
245 filter = damos_new_filter(DAMOS_FILTER_TYPE_ANON, true, false);
246 if (!filter)
247 goto out;
248 damos_add_filter(scheme, filter);
249 }
250
251 err = damon_set_region_biggest_system_ram_default(param_target,
252 &monitor_region_start,
253 &monitor_region_end,
254 param_ctx->min_sz_region);
255 if (err)
256 goto out;
257 err = damon_commit_ctx(ctx, param_ctx);
258 out:
259 damon_destroy_ctx(param_ctx);
260 return err;
261 }
262
damon_reclaim_handle_commit_inputs(void)263 static int damon_reclaim_handle_commit_inputs(void)
264 {
265 int err;
266
267 if (!commit_inputs)
268 return 0;
269
270 err = damon_reclaim_apply_parameters();
271 commit_inputs = false;
272 return err;
273 }
274
damon_reclaim_damon_call_fn(void * arg)275 static int damon_reclaim_damon_call_fn(void *arg)
276 {
277 struct damon_ctx *c = arg;
278 struct damos *s;
279
280 /* update the stats parameter */
281 damon_for_each_scheme(s, c)
282 damon_reclaim_stat = s->stat;
283
284 return damon_reclaim_handle_commit_inputs();
285 }
286
287 static struct damon_call_control call_control = {
288 .fn = damon_reclaim_damon_call_fn,
289 .repeat = true,
290 };
291
damon_reclaim_turn(bool on)292 static int damon_reclaim_turn(bool on)
293 {
294 int err;
295
296 if (!on) {
297 err = damon_stop(&ctx, 1);
298 if (!err)
299 kdamond_pid = -1;
300 return err;
301 }
302
303 err = damon_reclaim_apply_parameters();
304 if (err)
305 return err;
306
307 err = damon_start(&ctx, 1, true);
308 if (err)
309 return err;
310 kdamond_pid = ctx->kdamond->pid;
311 return damon_call(ctx, &call_control);
312 }
313
damon_reclaim_addr_unit_store(const char * val,const struct kernel_param * kp)314 static int damon_reclaim_addr_unit_store(const char *val,
315 const struct kernel_param *kp)
316 {
317 unsigned long input_addr_unit;
318 int err = kstrtoul(val, 0, &input_addr_unit);
319
320 if (err)
321 return err;
322 if (!input_addr_unit)
323 return -EINVAL;
324
325 addr_unit = input_addr_unit;
326 return 0;
327 }
328
329 static const struct kernel_param_ops addr_unit_param_ops = {
330 .set = damon_reclaim_addr_unit_store,
331 .get = param_get_ulong,
332 };
333
334 module_param_cb(addr_unit, &addr_unit_param_ops, &addr_unit, 0600);
335 MODULE_PARM_DESC(addr_unit,
336 "Scale factor for DAMON_RECLAIM to ops address conversion (default: 1)");
337
damon_reclaim_enabled_store(const char * val,const struct kernel_param * kp)338 static int damon_reclaim_enabled_store(const char *val,
339 const struct kernel_param *kp)
340 {
341 bool is_enabled = enabled;
342 bool enable;
343 int err;
344
345 err = kstrtobool(val, &enable);
346 if (err)
347 return err;
348
349 if (is_enabled == enable)
350 return 0;
351
352 /* Called before init function. The function will handle this. */
353 if (!damon_initialized())
354 goto set_param_out;
355
356 err = damon_reclaim_turn(enable);
357 if (err)
358 return err;
359
360 set_param_out:
361 enabled = enable;
362 return err;
363 }
364
365 static const struct kernel_param_ops enabled_param_ops = {
366 .set = damon_reclaim_enabled_store,
367 .get = param_get_bool,
368 };
369
370 module_param_cb(enabled, &enabled_param_ops, &enabled, 0600);
371 MODULE_PARM_DESC(enabled,
372 "Enable or disable DAMON_RECLAIM (default: disabled)");
373
damon_reclaim_init(void)374 static int __init damon_reclaim_init(void)
375 {
376 int err;
377
378 if (!damon_initialized()) {
379 err = -ENOMEM;
380 goto out;
381 }
382 err = damon_modules_new_paddr_ctx_target(&ctx, &target);
383 if (err)
384 goto out;
385
386 call_control.data = ctx;
387
388 /* 'enabled' has set before this function, probably via command line */
389 if (enabled)
390 err = damon_reclaim_turn(true);
391
392 out:
393 if (err && enabled)
394 enabled = false;
395 return err;
396 }
397
398 module_init(damon_reclaim_init);
399