lru_sort.c

  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 * Scale factor for DAMON_LRU_SORT to ops address conversion.
116 *
117 * This parameter must not be set to 0.
118 */
119static unsigned long addr_unit __read_mostly = 1;
120
121/*
122 * PID of the DAMON thread
123 *
124 * If DAMON_LRU_SORT is enabled, this becomes the PID of the worker thread.
125 * Else, -1.
126 */
127static int kdamond_pid __read_mostly = -1;
128module_param(kdamond_pid, int, 0400);
129
130static struct damos_stat damon_lru_sort_hot_stat;
131DEFINE_DAMON_MODULES_DAMOS_STATS_PARAMS(damon_lru_sort_hot_stat,
132		lru_sort_tried_hot_regions, lru_sorted_hot_regions,
133		hot_quota_exceeds);
134
135static struct damos_stat damon_lru_sort_cold_stat;
136DEFINE_DAMON_MODULES_DAMOS_STATS_PARAMS(damon_lru_sort_cold_stat,
137		lru_sort_tried_cold_regions, lru_sorted_cold_regions,
138		cold_quota_exceeds);
139
140static struct damos_access_pattern damon_lru_sort_stub_pattern = {
141	/* Find regions having PAGE_SIZE or larger size */
142	.min_sz_region = PAGE_SIZE,
143	.max_sz_region = ULONG_MAX,
144	/* no matter its access frequency */
145	.min_nr_accesses = 0,
146	.max_nr_accesses = UINT_MAX,
147	/* no matter its age */
148	.min_age_region = 0,
149	.max_age_region = UINT_MAX,
150};
151
152static struct damon_ctx *ctx;
153static struct damon_target *target;
154
155static struct damos *damon_lru_sort_new_scheme(
156		struct damos_access_pattern *pattern, enum damos_action action)
157{
158	struct damos_quota quota = damon_lru_sort_quota;
159
160	/* Use half of total quota for hot/cold pages sorting */
161	quota.ms = quota.ms / 2;
162
163	return damon_new_scheme(
164			/* find the pattern, and */
165			pattern,
166			/* (de)prioritize on LRU-lists */
167			action,
168			/* for each aggregation interval */
169			0,
170			/* under the quota. */
171			&quota,
172			/* (De)activate this according to the watermarks. */
173			&damon_lru_sort_wmarks,
174			NUMA_NO_NODE);
175}
176
177/* Create a DAMON-based operation scheme for hot memory regions */
178static struct damos *damon_lru_sort_new_hot_scheme(unsigned int hot_thres)
179{
180	struct damos_access_pattern pattern = damon_lru_sort_stub_pattern;
181
182	pattern.min_nr_accesses = hot_thres;
183	return damon_lru_sort_new_scheme(&pattern, DAMOS_LRU_PRIO);
184}
185
186/* Create a DAMON-based operation scheme for cold memory regions */
187static struct damos *damon_lru_sort_new_cold_scheme(unsigned int cold_thres)
188{
189	struct damos_access_pattern pattern = damon_lru_sort_stub_pattern;
190
191	pattern.max_nr_accesses = 0;
192	pattern.min_age_region = cold_thres;
193	return damon_lru_sort_new_scheme(&pattern, DAMOS_LRU_DEPRIO);
194}
195
196static int damon_lru_sort_apply_parameters(void)
197{
198	struct damon_ctx *param_ctx;
199	struct damon_target *param_target;
200	struct damos *hot_scheme, *cold_scheme;
201	unsigned int hot_thres, cold_thres;
202	int err;
203
204	err = damon_modules_new_paddr_ctx_target(&param_ctx, &param_target);
205	if (err)
206		return err;
207
208	/*
209	 * If monitor_region_start/end are unset, always silently
210	 * reset addr_unit to 1.
211	 */
212	if (!monitor_region_start && !monitor_region_end)
213		addr_unit = 1;
214	param_ctx->addr_unit = addr_unit;
215	param_ctx->min_region_sz = max(DAMON_MIN_REGION_SZ / addr_unit, 1);
216
217	if (!damon_lru_sort_mon_attrs.sample_interval) {
218		err = -EINVAL;
219		goto out;
220	}
221
222	err = damon_set_attrs(param_ctx, &damon_lru_sort_mon_attrs);
223	if (err)
224		goto out;
225
226	err = -ENOMEM;
227	hot_thres = damon_max_nr_accesses(&damon_lru_sort_mon_attrs) *
228		hot_thres_access_freq / 1000;
229	hot_scheme = damon_lru_sort_new_hot_scheme(hot_thres);
230	if (!hot_scheme)
231		goto out;
232
233	cold_thres = cold_min_age / damon_lru_sort_mon_attrs.aggr_interval;
234	cold_scheme = damon_lru_sort_new_cold_scheme(cold_thres);
235	if (!cold_scheme) {
236		damon_destroy_scheme(hot_scheme);
237		goto out;
238	}
239
240	damon_set_schemes(param_ctx, &hot_scheme, 1);
241	damon_add_scheme(param_ctx, cold_scheme);
242
243	err = damon_set_region_biggest_system_ram_default(param_target,
244					&monitor_region_start,
245					&monitor_region_end,
246					param_ctx->min_region_sz);
247	if (err)
248		goto out;
249	err = damon_commit_ctx(ctx, param_ctx);
250out:
251	damon_destroy_ctx(param_ctx);
252	return err;
253}
254
255static int damon_lru_sort_handle_commit_inputs(void)
256{
257	int err;
258
259	if (!commit_inputs)
260		return 0;
261
262	err = damon_lru_sort_apply_parameters();
263	commit_inputs = false;
264	return err;
265}
266
267static int damon_lru_sort_damon_call_fn(void *arg)
268{
269	struct damon_ctx *c = arg;
270	struct damos *s;
271
272	/* update the stats parameter */
273	damon_for_each_scheme(s, c) {
274		if (s->action == DAMOS_LRU_PRIO)
275			damon_lru_sort_hot_stat = s->stat;
276		else if (s->action == DAMOS_LRU_DEPRIO)
277			damon_lru_sort_cold_stat = s->stat;
278	}
279
280	return damon_lru_sort_handle_commit_inputs();
281}
282
283static struct damon_call_control call_control = {
284	.fn = damon_lru_sort_damon_call_fn,
285	.repeat = true,
286};
287
288static int damon_lru_sort_turn(bool on)
289{
290	int err;
291
292	if (!on) {
293		err = damon_stop(&ctx, 1);
294		if (!err)
295			kdamond_pid = -1;
296		return err;
297	}
298
299	err = damon_lru_sort_apply_parameters();
300	if (err)
301		return err;
302
303	err = damon_start(&ctx, 1, true);
304	if (err)
305		return err;
306	kdamond_pid = ctx->kdamond->pid;
307	return damon_call(ctx, &call_control);
308}
309
310static int damon_lru_sort_addr_unit_store(const char *val,
311		const struct kernel_param *kp)
312{
313	unsigned long input_addr_unit;
314	int err = kstrtoul(val, 0, &input_addr_unit);
315
316	if (err)
317		return err;
318	if (!input_addr_unit)
319		return -EINVAL;
320
321	addr_unit = input_addr_unit;
322	return 0;
323}
324
325static const struct kernel_param_ops addr_unit_param_ops = {
326	.set = damon_lru_sort_addr_unit_store,
327	.get = param_get_ulong,
328};
329
330module_param_cb(addr_unit, &addr_unit_param_ops, &addr_unit, 0600);
331MODULE_PARM_DESC(addr_unit,
332	"Scale factor for DAMON_LRU_SORT to ops address conversion (default: 1)");
333
334static int damon_lru_sort_enabled_store(const char *val,
335		const struct kernel_param *kp)
336{
337	bool is_enabled = enabled;
338	bool enable;
339	int err;
340
341	err = kstrtobool(val, &enable);
342	if (err)
343		return err;
344
345	if (is_enabled == enable)
346		return 0;
347
348	/* Called before init function.  The function will handle this. */
349	if (!damon_initialized())
350		goto set_param_out;
351
352	err = damon_lru_sort_turn(enable);
353	if (err)
354		return err;
355
356set_param_out:
357	enabled = enable;
358	return err;
359}
360
361static const struct kernel_param_ops enabled_param_ops = {
362	.set = damon_lru_sort_enabled_store,
363	.get = param_get_bool,
364};
365
366module_param_cb(enabled, &enabled_param_ops, &enabled, 0600);
367MODULE_PARM_DESC(enabled,
368	"Enable or disable DAMON_LRU_SORT (default: disabled)");
369
370static int __init damon_lru_sort_init(void)
371{
372	int err;
373
374	if (!damon_initialized()) {
375		err = -ENOMEM;
376		goto out;
377	}
378	err = damon_modules_new_paddr_ctx_target(&ctx, &target);
379	if (err)
380		goto out;
381
382	call_control.data = ctx;
383
384	/* 'enabled' has set before this function, probably via command line */
385	if (enabled)
386		err = damon_lru_sort_turn(true);
387
388out:
389	if (err && enabled)
390		enabled = false;
391	return err;
392}
393
394module_init(damon_lru_sort_init);