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