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			0,
163			/* under the quota. */
164			&quota,
165			/* (De)activate this according to the watermarks. */
166			&damon_lru_sort_wmarks,
167			NUMA_NO_NODE);
168}
169
170/* Create a DAMON-based operation scheme for hot memory regions */
171static struct damos *damon_lru_sort_new_hot_scheme(unsigned int hot_thres)
172{
173	struct damos_access_pattern pattern = damon_lru_sort_stub_pattern;
174
175	pattern.min_nr_accesses = hot_thres;
176	return damon_lru_sort_new_scheme(&pattern, DAMOS_LRU_PRIO);
177}
178
179/* Create a DAMON-based operation scheme for cold memory regions */
180static struct damos *damon_lru_sort_new_cold_scheme(unsigned int cold_thres)
181{
182	struct damos_access_pattern pattern = damon_lru_sort_stub_pattern;
183
184	pattern.max_nr_accesses = 0;
185	pattern.min_age_region = cold_thres;
186	return damon_lru_sort_new_scheme(&pattern, DAMOS_LRU_DEPRIO);
187}
188
189static int damon_lru_sort_apply_parameters(void)
190{
191	struct damon_ctx *param_ctx;
192	struct damon_target *param_target;
193	struct damos *hot_scheme, *cold_scheme;
194	unsigned int hot_thres, cold_thres;
195	int err;
196
197	err = damon_modules_new_paddr_ctx_target(&param_ctx, &param_target);
198	if (err)
199		return err;
200
201	err = damon_set_attrs(ctx, &damon_lru_sort_mon_attrs);
202	if (err)
203		goto out;
204
205	err = -ENOMEM;
206	hot_thres = damon_max_nr_accesses(&damon_lru_sort_mon_attrs) *
207		hot_thres_access_freq / 1000;
208	hot_scheme = damon_lru_sort_new_hot_scheme(hot_thres);
209	if (!hot_scheme)
210		goto out;
211
212	cold_thres = cold_min_age / damon_lru_sort_mon_attrs.aggr_interval;
213	cold_scheme = damon_lru_sort_new_cold_scheme(cold_thres);
214	if (!cold_scheme) {
215		damon_destroy_scheme(hot_scheme);
216		goto out;
217	}
218
219	damon_set_schemes(param_ctx, &hot_scheme, 1);
220	damon_add_scheme(param_ctx, cold_scheme);
221
222	err = damon_set_region_biggest_system_ram_default(param_target,
223					&monitor_region_start,
224					&monitor_region_end);
225	if (err)
226		goto out;
227	err = damon_commit_ctx(ctx, param_ctx);
228out:
229	damon_destroy_ctx(param_ctx);
230	return err;
231}
232
233static int damon_lru_sort_turn(bool on)
234{
235	int err;
236
237	if (!on) {
238		err = damon_stop(&ctx, 1);
239		if (!err)
240			kdamond_pid = -1;
241		return err;
242	}
243
244	err = damon_lru_sort_apply_parameters();
245	if (err)
246		return err;
247
248	err = damon_start(&ctx, 1, true);
249	if (err)
250		return err;
251	kdamond_pid = ctx->kdamond->pid;
252	return 0;
253}
254
255static int damon_lru_sort_enabled_store(const char *val,
256		const struct kernel_param *kp)
257{
258	bool is_enabled = enabled;
259	bool enable;
260	int err;
261
262	err = kstrtobool(val, &enable);
263	if (err)
264		return err;
265
266	if (is_enabled == enable)
267		return 0;
268
269	/* Called before init function.  The function will handle this. */
270	if (!ctx)
271		goto set_param_out;
272
273	err = damon_lru_sort_turn(enable);
274	if (err)
275		return err;
276
277set_param_out:
278	enabled = enable;
279	return err;
280}
281
282static const struct kernel_param_ops enabled_param_ops = {
283	.set = damon_lru_sort_enabled_store,
284	.get = param_get_bool,
285};
286
287module_param_cb(enabled, &enabled_param_ops, &enabled, 0600);
288MODULE_PARM_DESC(enabled,
289	"Enable or disable DAMON_LRU_SORT (default: disabled)");
290
291static int damon_lru_sort_handle_commit_inputs(void)
292{
293	int err;
294
295	if (!commit_inputs)
296		return 0;
297
298	err = damon_lru_sort_apply_parameters();
299	commit_inputs = false;
300	return err;
301}
302
303static int damon_lru_sort_after_aggregation(struct damon_ctx *c)
304{
305	struct damos *s;
306
307	/* update the stats parameter */
308	damon_for_each_scheme(s, c) {
309		if (s->action == DAMOS_LRU_PRIO)
310			damon_lru_sort_hot_stat = s->stat;
311		else if (s->action == DAMOS_LRU_DEPRIO)
312			damon_lru_sort_cold_stat = s->stat;
313	}
314
315	return damon_lru_sort_handle_commit_inputs();
316}
317
318static int damon_lru_sort_after_wmarks_check(struct damon_ctx *c)
319{
320	return damon_lru_sort_handle_commit_inputs();
321}
322
323static int __init damon_lru_sort_init(void)
324{
325	int err = damon_modules_new_paddr_ctx_target(&ctx, &target);
326
327	if (err)
328		return err;
329
330	ctx->callback.after_wmarks_check = damon_lru_sort_after_wmarks_check;
331	ctx->callback.after_aggregation = damon_lru_sort_after_aggregation;
332
333	/* 'enabled' has set before this function, probably via command line */
334	if (enabled)
335		err = damon_lru_sort_turn(true);
336
337	return err;
338}
339
340module_init(damon_lru_sort_init);