xref: /openbmc/linux/mm/damon/reclaim.c (revision 9cad9a2e)
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 static struct damos_watermarks damon_reclaim_wmarks = {
66 	.metric = DAMOS_WMARK_FREE_MEM_RATE,
67 	.interval = 5000000,	/* 5 seconds */
68 	.high = 500,		/* 50 percent */
69 	.mid = 400,		/* 40 percent */
70 	.low = 200,		/* 20 percent */
71 };
72 DEFINE_DAMON_MODULES_WMARKS_PARAMS(damon_reclaim_wmarks);
73 
74 static struct damon_attrs damon_reclaim_mon_attrs = {
75 	.sample_interval = 5000,	/* 5 ms */
76 	.aggr_interval = 100000,	/* 100 ms */
77 	.ops_update_interval = 0,
78 	.min_nr_regions = 10,
79 	.max_nr_regions = 1000,
80 };
81 DEFINE_DAMON_MODULES_MON_ATTRS_PARAMS(damon_reclaim_mon_attrs);
82 
83 /*
84  * Start of the target memory region in physical address.
85  *
86  * The start physical address of memory region that DAMON_RECLAIM will do work
87  * against.  By default, biggest System RAM is used as the region.
88  */
89 static unsigned long monitor_region_start __read_mostly;
90 module_param(monitor_region_start, ulong, 0600);
91 
92 /*
93  * End of the target memory region in physical address.
94  *
95  * The end physical address of memory region that DAMON_RECLAIM will do work
96  * against.  By default, biggest System RAM is used as the region.
97  */
98 static unsigned long monitor_region_end __read_mostly;
99 module_param(monitor_region_end, ulong, 0600);
100 
101 /*
102  * Skip anonymous pages reclamation.
103  *
104  * If this parameter is set as ``Y``, DAMON_RECLAIM does not reclaim anonymous
105  * pages.  By default, ``N``.
106  */
107 static bool skip_anon __read_mostly;
108 module_param(skip_anon, bool, 0600);
109 
110 /*
111  * PID of the DAMON thread
112  *
113  * If DAMON_RECLAIM is enabled, this becomes the PID of the worker thread.
114  * Else, -1.
115  */
116 static int kdamond_pid __read_mostly = -1;
117 module_param(kdamond_pid, int, 0400);
118 
119 static struct damos_stat damon_reclaim_stat;
120 DEFINE_DAMON_MODULES_DAMOS_STATS_PARAMS(damon_reclaim_stat,
121 		reclaim_tried_regions, reclaimed_regions, quota_exceeds);
122 
123 static struct damon_ctx *ctx;
124 static struct damon_target *target;
125 
damon_reclaim_new_scheme(void)126 static struct damos *damon_reclaim_new_scheme(void)
127 {
128 	struct damos_access_pattern pattern = {
129 		/* Find regions having PAGE_SIZE or larger size */
130 		.min_sz_region = PAGE_SIZE,
131 		.max_sz_region = ULONG_MAX,
132 		/* and not accessed at all */
133 		.min_nr_accesses = 0,
134 		.max_nr_accesses = 0,
135 		/* for min_age or more micro-seconds */
136 		.min_age_region = min_age /
137 			damon_reclaim_mon_attrs.aggr_interval,
138 		.max_age_region = UINT_MAX,
139 	};
140 
141 	return damon_new_scheme(
142 			&pattern,
143 			/* page out those, as soon as found */
144 			DAMOS_PAGEOUT,
145 			/* under the quota. */
146 			&damon_reclaim_quota,
147 			/* (De)activate this according to the watermarks. */
148 			&damon_reclaim_wmarks);
149 }
150 
damon_reclaim_copy_quota_status(struct damos_quota * dst,struct damos_quota * src)151 static void damon_reclaim_copy_quota_status(struct damos_quota *dst,
152 		struct damos_quota *src)
153 {
154 	dst->total_charged_sz = src->total_charged_sz;
155 	dst->total_charged_ns = src->total_charged_ns;
156 	dst->charged_sz = src->charged_sz;
157 	dst->charged_from = src->charged_from;
158 	dst->charge_target_from = src->charge_target_from;
159 	dst->charge_addr_from = src->charge_addr_from;
160 }
161 
damon_reclaim_apply_parameters(void)162 static int damon_reclaim_apply_parameters(void)
163 {
164 	struct damos *scheme, *old_scheme;
165 	struct damos_filter *filter;
166 	int err = 0;
167 
168 	err = damon_set_attrs(ctx, &damon_reclaim_mon_attrs);
169 	if (err)
170 		return err;
171 
172 	/* Will be freed by next 'damon_set_schemes()' below */
173 	scheme = damon_reclaim_new_scheme();
174 	if (!scheme)
175 		return -ENOMEM;
176 	if (!list_empty(&ctx->schemes)) {
177 		damon_for_each_scheme(old_scheme, ctx)
178 			damon_reclaim_copy_quota_status(&scheme->quota,
179 					&old_scheme->quota);
180 	}
181 	if (skip_anon) {
182 		filter = damos_new_filter(DAMOS_FILTER_TYPE_ANON, true);
183 		if (!filter) {
184 			/* Will be freed by next 'damon_set_schemes()' below */
185 			damon_destroy_scheme(scheme);
186 			return -ENOMEM;
187 		}
188 		damos_add_filter(scheme, filter);
189 	}
190 	damon_set_schemes(ctx, &scheme, 1);
191 
192 	return damon_set_region_biggest_system_ram_default(target,
193 					&monitor_region_start,
194 					&monitor_region_end);
195 }
196 
damon_reclaim_turn(bool on)197 static int damon_reclaim_turn(bool on)
198 {
199 	int err;
200 
201 	if (!on) {
202 		err = damon_stop(&ctx, 1);
203 		if (!err)
204 			kdamond_pid = -1;
205 		return err;
206 	}
207 
208 	err = damon_reclaim_apply_parameters();
209 	if (err)
210 		return err;
211 
212 	err = damon_start(&ctx, 1, true);
213 	if (err)
214 		return err;
215 	kdamond_pid = ctx->kdamond->pid;
216 	return 0;
217 }
218 
damon_reclaim_enabled_store(const char * val,const struct kernel_param * kp)219 static int damon_reclaim_enabled_store(const char *val,
220 		const struct kernel_param *kp)
221 {
222 	bool is_enabled = enabled;
223 	bool enable;
224 	int err;
225 
226 	err = kstrtobool(val, &enable);
227 	if (err)
228 		return err;
229 
230 	if (is_enabled == enable)
231 		return 0;
232 
233 	/* Called before init function.  The function will handle this. */
234 	if (!ctx)
235 		goto set_param_out;
236 
237 	err = damon_reclaim_turn(enable);
238 	if (err)
239 		return err;
240 
241 set_param_out:
242 	enabled = enable;
243 	return err;
244 }
245 
246 static const struct kernel_param_ops enabled_param_ops = {
247 	.set = damon_reclaim_enabled_store,
248 	.get = param_get_bool,
249 };
250 
251 module_param_cb(enabled, &enabled_param_ops, &enabled, 0600);
252 MODULE_PARM_DESC(enabled,
253 	"Enable or disable DAMON_RECLAIM (default: disabled)");
254 
damon_reclaim_handle_commit_inputs(void)255 static int damon_reclaim_handle_commit_inputs(void)
256 {
257 	int err;
258 
259 	if (!commit_inputs)
260 		return 0;
261 
262 	err = damon_reclaim_apply_parameters();
263 	commit_inputs = false;
264 	return err;
265 }
266 
damon_reclaim_after_aggregation(struct damon_ctx * c)267 static int damon_reclaim_after_aggregation(struct damon_ctx *c)
268 {
269 	struct damos *s;
270 
271 	/* update the stats parameter */
272 	damon_for_each_scheme(s, c)
273 		damon_reclaim_stat = s->stat;
274 
275 	return damon_reclaim_handle_commit_inputs();
276 }
277 
damon_reclaim_after_wmarks_check(struct damon_ctx * c)278 static int damon_reclaim_after_wmarks_check(struct damon_ctx *c)
279 {
280 	return damon_reclaim_handle_commit_inputs();
281 }
282 
damon_reclaim_init(void)283 static int __init damon_reclaim_init(void)
284 {
285 	int err = damon_modules_new_paddr_ctx_target(&ctx, &target);
286 
287 	if (err)
288 		return err;
289 
290 	ctx->callback.after_wmarks_check = damon_reclaim_after_wmarks_check;
291 	ctx->callback.after_aggregation = damon_reclaim_after_aggregation;
292 
293 	/* 'enabled' has set before this function, probably via command line */
294 	if (enabled)
295 		err = damon_reclaim_turn(true);
296 
297 	return err;
298 }
299 
300 module_init(damon_reclaim_init);
301