1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Data Access Monitor
4  *
5  * Author: SeongJae Park <sjpark@amazon.de>
6  */
7 
8 #define pr_fmt(fmt) "damon: " fmt
9 
10 #include <linux/damon.h>
11 #include <linux/delay.h>
12 #include <linux/kthread.h>
13 #include <linux/mm.h>
14 #include <linux/slab.h>
15 #include <linux/string.h>
16 
17 #define CREATE_TRACE_POINTS
18 #include <trace/events/damon.h>
19 
20 #ifdef CONFIG_DAMON_KUNIT_TEST
21 #undef DAMON_MIN_REGION
22 #define DAMON_MIN_REGION 1
23 #endif
24 
25 static DEFINE_MUTEX(damon_lock);
26 static int nr_running_ctxs;
27 static bool running_exclusive_ctxs;
28 
29 static DEFINE_MUTEX(damon_ops_lock);
30 static struct damon_operations damon_registered_ops[NR_DAMON_OPS];
31 
32 static struct kmem_cache *damon_region_cache __ro_after_init;
33 
34 /* Should be called under damon_ops_lock with id smaller than NR_DAMON_OPS */
__damon_is_registered_ops(enum damon_ops_id id)35 static bool __damon_is_registered_ops(enum damon_ops_id id)
36 {
37 	struct damon_operations empty_ops = {};
38 
39 	if (!memcmp(&empty_ops, &damon_registered_ops[id], sizeof(empty_ops)))
40 		return false;
41 	return true;
42 }
43 
44 /**
45  * damon_is_registered_ops() - Check if a given damon_operations is registered.
46  * @id:	Id of the damon_operations to check if registered.
47  *
48  * Return: true if the ops is set, false otherwise.
49  */
damon_is_registered_ops(enum damon_ops_id id)50 bool damon_is_registered_ops(enum damon_ops_id id)
51 {
52 	bool registered;
53 
54 	if (id >= NR_DAMON_OPS)
55 		return false;
56 	mutex_lock(&damon_ops_lock);
57 	registered = __damon_is_registered_ops(id);
58 	mutex_unlock(&damon_ops_lock);
59 	return registered;
60 }
61 
62 /**
63  * damon_register_ops() - Register a monitoring operations set to DAMON.
64  * @ops:	monitoring operations set to register.
65  *
66  * This function registers a monitoring operations set of valid &struct
67  * damon_operations->id so that others can find and use them later.
68  *
69  * Return: 0 on success, negative error code otherwise.
70  */
damon_register_ops(struct damon_operations * ops)71 int damon_register_ops(struct damon_operations *ops)
72 {
73 	int err = 0;
74 
75 	if (ops->id >= NR_DAMON_OPS)
76 		return -EINVAL;
77 	mutex_lock(&damon_ops_lock);
78 	/* Fail for already registered ops */
79 	if (__damon_is_registered_ops(ops->id)) {
80 		err = -EINVAL;
81 		goto out;
82 	}
83 	damon_registered_ops[ops->id] = *ops;
84 out:
85 	mutex_unlock(&damon_ops_lock);
86 	return err;
87 }
88 
89 /**
90  * damon_select_ops() - Select a monitoring operations to use with the context.
91  * @ctx:	monitoring context to use the operations.
92  * @id:		id of the registered monitoring operations to select.
93  *
94  * This function finds registered monitoring operations set of @id and make
95  * @ctx to use it.
96  *
97  * Return: 0 on success, negative error code otherwise.
98  */
damon_select_ops(struct damon_ctx * ctx,enum damon_ops_id id)99 int damon_select_ops(struct damon_ctx *ctx, enum damon_ops_id id)
100 {
101 	int err = 0;
102 
103 	if (id >= NR_DAMON_OPS)
104 		return -EINVAL;
105 
106 	mutex_lock(&damon_ops_lock);
107 	if (!__damon_is_registered_ops(id))
108 		err = -EINVAL;
109 	else
110 		ctx->ops = damon_registered_ops[id];
111 	mutex_unlock(&damon_ops_lock);
112 	return err;
113 }
114 
115 /*
116  * Construct a damon_region struct
117  *
118  * Returns the pointer to the new struct if success, or NULL otherwise
119  */
damon_new_region(unsigned long start,unsigned long end)120 struct damon_region *damon_new_region(unsigned long start, unsigned long end)
121 {
122 	struct damon_region *region;
123 
124 	region = kmem_cache_alloc(damon_region_cache, GFP_KERNEL);
125 	if (!region)
126 		return NULL;
127 
128 	region->ar.start = start;
129 	region->ar.end = end;
130 	region->nr_accesses = 0;
131 	INIT_LIST_HEAD(&region->list);
132 
133 	region->age = 0;
134 	region->last_nr_accesses = 0;
135 
136 	return region;
137 }
138 
damon_add_region(struct damon_region * r,struct damon_target * t)139 void damon_add_region(struct damon_region *r, struct damon_target *t)
140 {
141 	list_add_tail(&r->list, &t->regions_list);
142 	t->nr_regions++;
143 }
144 
damon_del_region(struct damon_region * r,struct damon_target * t)145 static void damon_del_region(struct damon_region *r, struct damon_target *t)
146 {
147 	list_del(&r->list);
148 	t->nr_regions--;
149 }
150 
damon_free_region(struct damon_region * r)151 static void damon_free_region(struct damon_region *r)
152 {
153 	kmem_cache_free(damon_region_cache, r);
154 }
155 
damon_destroy_region(struct damon_region * r,struct damon_target * t)156 void damon_destroy_region(struct damon_region *r, struct damon_target *t)
157 {
158 	damon_del_region(r, t);
159 	damon_free_region(r);
160 }
161 
162 /*
163  * Check whether a region is intersecting an address range
164  *
165  * Returns true if it is.
166  */
damon_intersect(struct damon_region * r,struct damon_addr_range * re)167 static bool damon_intersect(struct damon_region *r,
168 		struct damon_addr_range *re)
169 {
170 	return !(r->ar.end <= re->start || re->end <= r->ar.start);
171 }
172 
173 /*
174  * Fill holes in regions with new regions.
175  */
damon_fill_regions_holes(struct damon_region * first,struct damon_region * last,struct damon_target * t)176 static int damon_fill_regions_holes(struct damon_region *first,
177 		struct damon_region *last, struct damon_target *t)
178 {
179 	struct damon_region *r = first;
180 
181 	damon_for_each_region_from(r, t) {
182 		struct damon_region *next, *newr;
183 
184 		if (r == last)
185 			break;
186 		next = damon_next_region(r);
187 		if (r->ar.end != next->ar.start) {
188 			newr = damon_new_region(r->ar.end, next->ar.start);
189 			if (!newr)
190 				return -ENOMEM;
191 			damon_insert_region(newr, r, next, t);
192 		}
193 	}
194 	return 0;
195 }
196 
197 /*
198  * damon_set_regions() - Set regions of a target for given address ranges.
199  * @t:		the given target.
200  * @ranges:	array of new monitoring target ranges.
201  * @nr_ranges:	length of @ranges.
202  *
203  * This function adds new regions to, or modify existing regions of a
204  * monitoring target to fit in specific ranges.
205  *
206  * Return: 0 if success, or negative error code otherwise.
207  */
damon_set_regions(struct damon_target * t,struct damon_addr_range * ranges,unsigned int nr_ranges)208 int damon_set_regions(struct damon_target *t, struct damon_addr_range *ranges,
209 		unsigned int nr_ranges)
210 {
211 	struct damon_region *r, *next;
212 	unsigned int i;
213 	int err;
214 
215 	/* Remove regions which are not in the new ranges */
216 	damon_for_each_region_safe(r, next, t) {
217 		for (i = 0; i < nr_ranges; i++) {
218 			if (damon_intersect(r, &ranges[i]))
219 				break;
220 		}
221 		if (i == nr_ranges)
222 			damon_destroy_region(r, t);
223 	}
224 
225 	r = damon_first_region(t);
226 	/* Add new regions or resize existing regions to fit in the ranges */
227 	for (i = 0; i < nr_ranges; i++) {
228 		struct damon_region *first = NULL, *last, *newr;
229 		struct damon_addr_range *range;
230 
231 		range = &ranges[i];
232 		/* Get the first/last regions intersecting with the range */
233 		damon_for_each_region_from(r, t) {
234 			if (damon_intersect(r, range)) {
235 				if (!first)
236 					first = r;
237 				last = r;
238 			}
239 			if (r->ar.start >= range->end)
240 				break;
241 		}
242 		if (!first) {
243 			/* no region intersects with this range */
244 			newr = damon_new_region(
245 					ALIGN_DOWN(range->start,
246 						DAMON_MIN_REGION),
247 					ALIGN(range->end, DAMON_MIN_REGION));
248 			if (!newr)
249 				return -ENOMEM;
250 			damon_insert_region(newr, damon_prev_region(r), r, t);
251 		} else {
252 			/* resize intersecting regions to fit in this range */
253 			first->ar.start = ALIGN_DOWN(range->start,
254 					DAMON_MIN_REGION);
255 			last->ar.end = ALIGN(range->end, DAMON_MIN_REGION);
256 
257 			/* fill possible holes in the range */
258 			err = damon_fill_regions_holes(first, last, t);
259 			if (err)
260 				return err;
261 		}
262 	}
263 	return 0;
264 }
265 
266 /* initialize private fields of damos_quota and return the pointer */
damos_quota_init_priv(struct damos_quota * quota)267 static struct damos_quota *damos_quota_init_priv(struct damos_quota *quota)
268 {
269 	quota->total_charged_sz = 0;
270 	quota->total_charged_ns = 0;
271 	quota->esz = 0;
272 	quota->charged_sz = 0;
273 	quota->charged_from = 0;
274 	quota->charge_target_from = NULL;
275 	quota->charge_addr_from = 0;
276 	return quota;
277 }
278 
damon_new_scheme(struct damos_access_pattern * pattern,enum damos_action action,struct damos_quota * quota,struct damos_watermarks * wmarks)279 struct damos *damon_new_scheme(struct damos_access_pattern *pattern,
280 			enum damos_action action, struct damos_quota *quota,
281 			struct damos_watermarks *wmarks)
282 {
283 	struct damos *scheme;
284 
285 	scheme = kmalloc(sizeof(*scheme), GFP_KERNEL);
286 	if (!scheme)
287 		return NULL;
288 	scheme->pattern = *pattern;
289 	scheme->action = action;
290 	scheme->stat = (struct damos_stat){};
291 	INIT_LIST_HEAD(&scheme->list);
292 
293 	scheme->quota = *(damos_quota_init_priv(quota));
294 
295 	scheme->wmarks = *wmarks;
296 	scheme->wmarks.activated = true;
297 
298 	return scheme;
299 }
300 
damon_add_scheme(struct damon_ctx * ctx,struct damos * s)301 void damon_add_scheme(struct damon_ctx *ctx, struct damos *s)
302 {
303 	list_add_tail(&s->list, &ctx->schemes);
304 }
305 
damon_del_scheme(struct damos * s)306 static void damon_del_scheme(struct damos *s)
307 {
308 	list_del(&s->list);
309 }
310 
damon_free_scheme(struct damos * s)311 static void damon_free_scheme(struct damos *s)
312 {
313 	kfree(s);
314 }
315 
damon_destroy_scheme(struct damos * s)316 void damon_destroy_scheme(struct damos *s)
317 {
318 	damon_del_scheme(s);
319 	damon_free_scheme(s);
320 }
321 
322 /*
323  * Construct a damon_target struct
324  *
325  * Returns the pointer to the new struct if success, or NULL otherwise
326  */
damon_new_target(void)327 struct damon_target *damon_new_target(void)
328 {
329 	struct damon_target *t;
330 
331 	t = kmalloc(sizeof(*t), GFP_KERNEL);
332 	if (!t)
333 		return NULL;
334 
335 	t->pid = NULL;
336 	t->nr_regions = 0;
337 	INIT_LIST_HEAD(&t->regions_list);
338 	INIT_LIST_HEAD(&t->list);
339 
340 	return t;
341 }
342 
damon_add_target(struct damon_ctx * ctx,struct damon_target * t)343 void damon_add_target(struct damon_ctx *ctx, struct damon_target *t)
344 {
345 	list_add_tail(&t->list, &ctx->adaptive_targets);
346 }
347 
damon_targets_empty(struct damon_ctx * ctx)348 bool damon_targets_empty(struct damon_ctx *ctx)
349 {
350 	return list_empty(&ctx->adaptive_targets);
351 }
352 
damon_del_target(struct damon_target * t)353 static void damon_del_target(struct damon_target *t)
354 {
355 	list_del(&t->list);
356 }
357 
damon_free_target(struct damon_target * t)358 void damon_free_target(struct damon_target *t)
359 {
360 	struct damon_region *r, *next;
361 
362 	damon_for_each_region_safe(r, next, t)
363 		damon_free_region(r);
364 	kfree(t);
365 }
366 
damon_destroy_target(struct damon_target * t)367 void damon_destroy_target(struct damon_target *t)
368 {
369 	damon_del_target(t);
370 	damon_free_target(t);
371 }
372 
damon_nr_regions(struct damon_target * t)373 unsigned int damon_nr_regions(struct damon_target *t)
374 {
375 	return t->nr_regions;
376 }
377 
damon_new_ctx(void)378 struct damon_ctx *damon_new_ctx(void)
379 {
380 	struct damon_ctx *ctx;
381 
382 	ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
383 	if (!ctx)
384 		return NULL;
385 
386 	ctx->attrs.sample_interval = 5 * 1000;
387 	ctx->attrs.aggr_interval = 100 * 1000;
388 	ctx->attrs.ops_update_interval = 60 * 1000 * 1000;
389 
390 	ktime_get_coarse_ts64(&ctx->last_aggregation);
391 	ctx->last_ops_update = ctx->last_aggregation;
392 
393 	mutex_init(&ctx->kdamond_lock);
394 
395 	ctx->attrs.min_nr_regions = 10;
396 	ctx->attrs.max_nr_regions = 1000;
397 
398 	INIT_LIST_HEAD(&ctx->adaptive_targets);
399 	INIT_LIST_HEAD(&ctx->schemes);
400 
401 	return ctx;
402 }
403 
damon_destroy_targets(struct damon_ctx * ctx)404 static void damon_destroy_targets(struct damon_ctx *ctx)
405 {
406 	struct damon_target *t, *next_t;
407 
408 	if (ctx->ops.cleanup) {
409 		ctx->ops.cleanup(ctx);
410 		return;
411 	}
412 
413 	damon_for_each_target_safe(t, next_t, ctx)
414 		damon_destroy_target(t);
415 }
416 
damon_destroy_ctx(struct damon_ctx * ctx)417 void damon_destroy_ctx(struct damon_ctx *ctx)
418 {
419 	struct damos *s, *next_s;
420 
421 	damon_destroy_targets(ctx);
422 
423 	damon_for_each_scheme_safe(s, next_s, ctx)
424 		damon_destroy_scheme(s);
425 
426 	kfree(ctx);
427 }
428 
429 /**
430  * damon_set_attrs() - Set attributes for the monitoring.
431  * @ctx:		monitoring context
432  * @attrs:		monitoring attributes
433  *
434  * This function should not be called while the kdamond is running.
435  * Every time interval is in micro-seconds.
436  *
437  * Return: 0 on success, negative error code otherwise.
438  */
damon_set_attrs(struct damon_ctx * ctx,struct damon_attrs * attrs)439 int damon_set_attrs(struct damon_ctx *ctx, struct damon_attrs *attrs)
440 {
441 	if (attrs->min_nr_regions < 3)
442 		return -EINVAL;
443 	if (attrs->min_nr_regions > attrs->max_nr_regions)
444 		return -EINVAL;
445 
446 	ctx->attrs = *attrs;
447 	return 0;
448 }
449 
450 /**
451  * damon_set_schemes() - Set data access monitoring based operation schemes.
452  * @ctx:	monitoring context
453  * @schemes:	array of the schemes
454  * @nr_schemes:	number of entries in @schemes
455  *
456  * This function should not be called while the kdamond of the context is
457  * running.
458  */
damon_set_schemes(struct damon_ctx * ctx,struct damos ** schemes,ssize_t nr_schemes)459 void damon_set_schemes(struct damon_ctx *ctx, struct damos **schemes,
460 			ssize_t nr_schemes)
461 {
462 	struct damos *s, *next;
463 	ssize_t i;
464 
465 	damon_for_each_scheme_safe(s, next, ctx)
466 		damon_destroy_scheme(s);
467 	for (i = 0; i < nr_schemes; i++)
468 		damon_add_scheme(ctx, schemes[i]);
469 }
470 
471 /**
472  * damon_nr_running_ctxs() - Return number of currently running contexts.
473  */
damon_nr_running_ctxs(void)474 int damon_nr_running_ctxs(void)
475 {
476 	int nr_ctxs;
477 
478 	mutex_lock(&damon_lock);
479 	nr_ctxs = nr_running_ctxs;
480 	mutex_unlock(&damon_lock);
481 
482 	return nr_ctxs;
483 }
484 
485 /* Returns the size upper limit for each monitoring region */
damon_region_sz_limit(struct damon_ctx * ctx)486 static unsigned long damon_region_sz_limit(struct damon_ctx *ctx)
487 {
488 	struct damon_target *t;
489 	struct damon_region *r;
490 	unsigned long sz = 0;
491 
492 	damon_for_each_target(t, ctx) {
493 		damon_for_each_region(r, t)
494 			sz += damon_sz_region(r);
495 	}
496 
497 	if (ctx->attrs.min_nr_regions)
498 		sz /= ctx->attrs.min_nr_regions;
499 	if (sz < DAMON_MIN_REGION)
500 		sz = DAMON_MIN_REGION;
501 
502 	return sz;
503 }
504 
505 static int kdamond_fn(void *data);
506 
507 /*
508  * __damon_start() - Starts monitoring with given context.
509  * @ctx:	monitoring context
510  *
511  * This function should be called while damon_lock is hold.
512  *
513  * Return: 0 on success, negative error code otherwise.
514  */
__damon_start(struct damon_ctx * ctx)515 static int __damon_start(struct damon_ctx *ctx)
516 {
517 	int err = -EBUSY;
518 
519 	mutex_lock(&ctx->kdamond_lock);
520 	if (!ctx->kdamond) {
521 		err = 0;
522 		ctx->kdamond = kthread_run(kdamond_fn, ctx, "kdamond.%d",
523 				nr_running_ctxs);
524 		if (IS_ERR(ctx->kdamond)) {
525 			err = PTR_ERR(ctx->kdamond);
526 			ctx->kdamond = NULL;
527 		}
528 	}
529 	mutex_unlock(&ctx->kdamond_lock);
530 
531 	return err;
532 }
533 
534 /**
535  * damon_start() - Starts the monitorings for a given group of contexts.
536  * @ctxs:	an array of the pointers for contexts to start monitoring
537  * @nr_ctxs:	size of @ctxs
538  * @exclusive:	exclusiveness of this contexts group
539  *
540  * This function starts a group of monitoring threads for a group of monitoring
541  * contexts.  One thread per each context is created and run in parallel.  The
542  * caller should handle synchronization between the threads by itself.  If
543  * @exclusive is true and a group of threads that created by other
544  * 'damon_start()' call is currently running, this function does nothing but
545  * returns -EBUSY.
546  *
547  * Return: 0 on success, negative error code otherwise.
548  */
damon_start(struct damon_ctx ** ctxs,int nr_ctxs,bool exclusive)549 int damon_start(struct damon_ctx **ctxs, int nr_ctxs, bool exclusive)
550 {
551 	int i;
552 	int err = 0;
553 
554 	mutex_lock(&damon_lock);
555 	if ((exclusive && nr_running_ctxs) ||
556 			(!exclusive && running_exclusive_ctxs)) {
557 		mutex_unlock(&damon_lock);
558 		return -EBUSY;
559 	}
560 
561 	for (i = 0; i < nr_ctxs; i++) {
562 		err = __damon_start(ctxs[i]);
563 		if (err)
564 			break;
565 		nr_running_ctxs++;
566 	}
567 	if (exclusive && nr_running_ctxs)
568 		running_exclusive_ctxs = true;
569 	mutex_unlock(&damon_lock);
570 
571 	return err;
572 }
573 
574 /*
575  * __damon_stop() - Stops monitoring of a given context.
576  * @ctx:	monitoring context
577  *
578  * Return: 0 on success, negative error code otherwise.
579  */
__damon_stop(struct damon_ctx * ctx)580 static int __damon_stop(struct damon_ctx *ctx)
581 {
582 	struct task_struct *tsk;
583 
584 	mutex_lock(&ctx->kdamond_lock);
585 	tsk = ctx->kdamond;
586 	if (tsk) {
587 		get_task_struct(tsk);
588 		mutex_unlock(&ctx->kdamond_lock);
589 		kthread_stop(tsk);
590 		put_task_struct(tsk);
591 		return 0;
592 	}
593 	mutex_unlock(&ctx->kdamond_lock);
594 
595 	return -EPERM;
596 }
597 
598 /**
599  * damon_stop() - Stops the monitorings for a given group of contexts.
600  * @ctxs:	an array of the pointers for contexts to stop monitoring
601  * @nr_ctxs:	size of @ctxs
602  *
603  * Return: 0 on success, negative error code otherwise.
604  */
damon_stop(struct damon_ctx ** ctxs,int nr_ctxs)605 int damon_stop(struct damon_ctx **ctxs, int nr_ctxs)
606 {
607 	int i, err = 0;
608 
609 	for (i = 0; i < nr_ctxs; i++) {
610 		/* nr_running_ctxs is decremented in kdamond_fn */
611 		err = __damon_stop(ctxs[i]);
612 		if (err)
613 			break;
614 	}
615 	return err;
616 }
617 
618 /*
619  * damon_check_reset_time_interval() - Check if a time interval is elapsed.
620  * @baseline:	the time to check whether the interval has elapsed since
621  * @interval:	the time interval (microseconds)
622  *
623  * See whether the given time interval has passed since the given baseline
624  * time.  If so, it also updates the baseline to current time for next check.
625  *
626  * Return:	true if the time interval has passed, or false otherwise.
627  */
damon_check_reset_time_interval(struct timespec64 * baseline,unsigned long interval)628 static bool damon_check_reset_time_interval(struct timespec64 *baseline,
629 		unsigned long interval)
630 {
631 	struct timespec64 now;
632 
633 	ktime_get_coarse_ts64(&now);
634 	if ((timespec64_to_ns(&now) - timespec64_to_ns(baseline)) <
635 			interval * 1000)
636 		return false;
637 	*baseline = now;
638 	return true;
639 }
640 
641 /*
642  * Check whether it is time to flush the aggregated information
643  */
kdamond_aggregate_interval_passed(struct damon_ctx * ctx)644 static bool kdamond_aggregate_interval_passed(struct damon_ctx *ctx)
645 {
646 	return damon_check_reset_time_interval(&ctx->last_aggregation,
647 			ctx->attrs.aggr_interval);
648 }
649 
650 /*
651  * Reset the aggregated monitoring results ('nr_accesses' of each region).
652  */
kdamond_reset_aggregated(struct damon_ctx * c)653 static void kdamond_reset_aggregated(struct damon_ctx *c)
654 {
655 	struct damon_target *t;
656 	unsigned int ti = 0;	/* target's index */
657 
658 	damon_for_each_target(t, c) {
659 		struct damon_region *r;
660 
661 		damon_for_each_region(r, t) {
662 			trace_damon_aggregated(t, ti, r, damon_nr_regions(t));
663 			r->last_nr_accesses = r->nr_accesses;
664 			r->nr_accesses = 0;
665 		}
666 		ti++;
667 	}
668 }
669 
670 static void damon_split_region_at(struct damon_target *t,
671 				  struct damon_region *r, unsigned long sz_r);
672 
__damos_valid_target(struct damon_region * r,struct damos * s)673 static bool __damos_valid_target(struct damon_region *r, struct damos *s)
674 {
675 	unsigned long sz;
676 
677 	sz = damon_sz_region(r);
678 	return s->pattern.min_sz_region <= sz &&
679 		sz <= s->pattern.max_sz_region &&
680 		s->pattern.min_nr_accesses <= r->nr_accesses &&
681 		r->nr_accesses <= s->pattern.max_nr_accesses &&
682 		s->pattern.min_age_region <= r->age &&
683 		r->age <= s->pattern.max_age_region;
684 }
685 
damos_valid_target(struct damon_ctx * c,struct damon_target * t,struct damon_region * r,struct damos * s)686 static bool damos_valid_target(struct damon_ctx *c, struct damon_target *t,
687 		struct damon_region *r, struct damos *s)
688 {
689 	bool ret = __damos_valid_target(r, s);
690 
691 	if (!ret || !s->quota.esz || !c->ops.get_scheme_score)
692 		return ret;
693 
694 	return c->ops.get_scheme_score(c, t, r, s) >= s->quota.min_score;
695 }
696 
damon_do_apply_schemes(struct damon_ctx * c,struct damon_target * t,struct damon_region * r)697 static void damon_do_apply_schemes(struct damon_ctx *c,
698 				   struct damon_target *t,
699 				   struct damon_region *r)
700 {
701 	struct damos *s;
702 
703 	damon_for_each_scheme(s, c) {
704 		struct damos_quota *quota = &s->quota;
705 		unsigned long sz = damon_sz_region(r);
706 		struct timespec64 begin, end;
707 		unsigned long sz_applied = 0;
708 
709 		if (!s->wmarks.activated)
710 			continue;
711 
712 		/* Check the quota */
713 		if (quota->esz && quota->charged_sz >= quota->esz)
714 			continue;
715 
716 		/* Skip previously charged regions */
717 		if (quota->charge_target_from) {
718 			if (t != quota->charge_target_from)
719 				continue;
720 			if (r == damon_last_region(t)) {
721 				quota->charge_target_from = NULL;
722 				quota->charge_addr_from = 0;
723 				continue;
724 			}
725 			if (quota->charge_addr_from &&
726 					r->ar.end <= quota->charge_addr_from)
727 				continue;
728 
729 			if (quota->charge_addr_from && r->ar.start <
730 					quota->charge_addr_from) {
731 				sz = ALIGN_DOWN(quota->charge_addr_from -
732 						r->ar.start, DAMON_MIN_REGION);
733 				if (!sz) {
734 					if (damon_sz_region(r) <=
735 					    DAMON_MIN_REGION)
736 						continue;
737 					sz = DAMON_MIN_REGION;
738 				}
739 				damon_split_region_at(t, r, sz);
740 				r = damon_next_region(r);
741 				sz = damon_sz_region(r);
742 			}
743 			quota->charge_target_from = NULL;
744 			quota->charge_addr_from = 0;
745 		}
746 
747 		if (!damos_valid_target(c, t, r, s))
748 			continue;
749 
750 		/* Apply the scheme */
751 		if (c->ops.apply_scheme) {
752 			if (quota->esz &&
753 					quota->charged_sz + sz > quota->esz) {
754 				sz = ALIGN_DOWN(quota->esz - quota->charged_sz,
755 						DAMON_MIN_REGION);
756 				if (!sz)
757 					goto update_stat;
758 				damon_split_region_at(t, r, sz);
759 			}
760 			ktime_get_coarse_ts64(&begin);
761 			sz_applied = c->ops.apply_scheme(c, t, r, s);
762 			ktime_get_coarse_ts64(&end);
763 			quota->total_charged_ns += timespec64_to_ns(&end) -
764 				timespec64_to_ns(&begin);
765 			quota->charged_sz += sz;
766 			if (quota->esz && quota->charged_sz >= quota->esz) {
767 				quota->charge_target_from = t;
768 				quota->charge_addr_from = r->ar.end + 1;
769 			}
770 		}
771 		if (s->action != DAMOS_STAT)
772 			r->age = 0;
773 
774 update_stat:
775 		s->stat.nr_tried++;
776 		s->stat.sz_tried += sz;
777 		if (sz_applied)
778 			s->stat.nr_applied++;
779 		s->stat.sz_applied += sz_applied;
780 	}
781 }
782 
783 /* Shouldn't be called if quota->ms and quota->sz are zero */
damos_set_effective_quota(struct damos_quota * quota)784 static void damos_set_effective_quota(struct damos_quota *quota)
785 {
786 	unsigned long throughput;
787 	unsigned long esz;
788 
789 	if (!quota->ms) {
790 		quota->esz = quota->sz;
791 		return;
792 	}
793 
794 	if (quota->total_charged_ns)
795 		throughput = quota->total_charged_sz * 1000000 /
796 			quota->total_charged_ns;
797 	else
798 		throughput = PAGE_SIZE * 1024;
799 	esz = throughput * quota->ms;
800 
801 	if (quota->sz && quota->sz < esz)
802 		esz = quota->sz;
803 	quota->esz = esz;
804 }
805 
kdamond_apply_schemes(struct damon_ctx * c)806 static void kdamond_apply_schemes(struct damon_ctx *c)
807 {
808 	struct damon_target *t;
809 	struct damon_region *r, *next_r;
810 	struct damos *s;
811 
812 	damon_for_each_scheme(s, c) {
813 		struct damos_quota *quota = &s->quota;
814 		unsigned long cumulated_sz;
815 		unsigned int score, max_score = 0;
816 
817 		if (!s->wmarks.activated)
818 			continue;
819 
820 		if (!quota->ms && !quota->sz)
821 			continue;
822 
823 		/* New charge window starts */
824 		if (time_after_eq(jiffies, quota->charged_from +
825 					msecs_to_jiffies(
826 						quota->reset_interval))) {
827 			if (quota->esz && quota->charged_sz >= quota->esz)
828 				s->stat.qt_exceeds++;
829 			quota->total_charged_sz += quota->charged_sz;
830 			quota->charged_from = jiffies;
831 			quota->charged_sz = 0;
832 			damos_set_effective_quota(quota);
833 		}
834 
835 		if (!c->ops.get_scheme_score)
836 			continue;
837 
838 		/* Fill up the score histogram */
839 		memset(quota->histogram, 0, sizeof(quota->histogram));
840 		damon_for_each_target(t, c) {
841 			damon_for_each_region(r, t) {
842 				if (!__damos_valid_target(r, s))
843 					continue;
844 				score = c->ops.get_scheme_score(
845 						c, t, r, s);
846 				quota->histogram[score] += damon_sz_region(r);
847 				if (score > max_score)
848 					max_score = score;
849 			}
850 		}
851 
852 		/* Set the min score limit */
853 		for (cumulated_sz = 0, score = max_score; ; score--) {
854 			cumulated_sz += quota->histogram[score];
855 			if (cumulated_sz >= quota->esz || !score)
856 				break;
857 		}
858 		quota->min_score = score;
859 	}
860 
861 	damon_for_each_target(t, c) {
862 		damon_for_each_region_safe(r, next_r, t)
863 			damon_do_apply_schemes(c, t, r);
864 	}
865 }
866 
867 /*
868  * Merge two adjacent regions into one region
869  */
damon_merge_two_regions(struct damon_target * t,struct damon_region * l,struct damon_region * r)870 static void damon_merge_two_regions(struct damon_target *t,
871 		struct damon_region *l, struct damon_region *r)
872 {
873 	unsigned long sz_l = damon_sz_region(l), sz_r = damon_sz_region(r);
874 
875 	l->nr_accesses = (l->nr_accesses * sz_l + r->nr_accesses * sz_r) /
876 			(sz_l + sz_r);
877 	l->age = (l->age * sz_l + r->age * sz_r) / (sz_l + sz_r);
878 	l->ar.end = r->ar.end;
879 	damon_destroy_region(r, t);
880 }
881 
882 /*
883  * Merge adjacent regions having similar access frequencies
884  *
885  * t		target affected by this merge operation
886  * thres	'->nr_accesses' diff threshold for the merge
887  * sz_limit	size upper limit of each region
888  */
damon_merge_regions_of(struct damon_target * t,unsigned int thres,unsigned long sz_limit)889 static void damon_merge_regions_of(struct damon_target *t, unsigned int thres,
890 				   unsigned long sz_limit)
891 {
892 	struct damon_region *r, *prev = NULL, *next;
893 
894 	damon_for_each_region_safe(r, next, t) {
895 		if (abs(r->nr_accesses - r->last_nr_accesses) > thres)
896 			r->age = 0;
897 		else
898 			r->age++;
899 
900 		if (prev && prev->ar.end == r->ar.start &&
901 		    abs(prev->nr_accesses - r->nr_accesses) <= thres &&
902 		    damon_sz_region(prev) + damon_sz_region(r) <= sz_limit)
903 			damon_merge_two_regions(t, prev, r);
904 		else
905 			prev = r;
906 	}
907 }
908 
909 /*
910  * Merge adjacent regions having similar access frequencies
911  *
912  * threshold	'->nr_accesses' diff threshold for the merge
913  * sz_limit	size upper limit of each region
914  *
915  * This function merges monitoring target regions which are adjacent and their
916  * access frequencies are similar.  This is for minimizing the monitoring
917  * overhead under the dynamically changeable access pattern.  If a merge was
918  * unnecessarily made, later 'kdamond_split_regions()' will revert it.
919  */
kdamond_merge_regions(struct damon_ctx * c,unsigned int threshold,unsigned long sz_limit)920 static void kdamond_merge_regions(struct damon_ctx *c, unsigned int threshold,
921 				  unsigned long sz_limit)
922 {
923 	struct damon_target *t;
924 
925 	damon_for_each_target(t, c)
926 		damon_merge_regions_of(t, threshold, sz_limit);
927 }
928 
929 /*
930  * Split a region in two
931  *
932  * r		the region to be split
933  * sz_r		size of the first sub-region that will be made
934  */
damon_split_region_at(struct damon_target * t,struct damon_region * r,unsigned long sz_r)935 static void damon_split_region_at(struct damon_target *t,
936 				  struct damon_region *r, unsigned long sz_r)
937 {
938 	struct damon_region *new;
939 
940 	new = damon_new_region(r->ar.start + sz_r, r->ar.end);
941 	if (!new)
942 		return;
943 
944 	r->ar.end = new->ar.start;
945 
946 	new->age = r->age;
947 	new->last_nr_accesses = r->last_nr_accesses;
948 
949 	damon_insert_region(new, r, damon_next_region(r), t);
950 }
951 
952 /* Split every region in the given target into 'nr_subs' regions */
damon_split_regions_of(struct damon_target * t,int nr_subs)953 static void damon_split_regions_of(struct damon_target *t, int nr_subs)
954 {
955 	struct damon_region *r, *next;
956 	unsigned long sz_region, sz_sub = 0;
957 	int i;
958 
959 	damon_for_each_region_safe(r, next, t) {
960 		sz_region = damon_sz_region(r);
961 
962 		for (i = 0; i < nr_subs - 1 &&
963 				sz_region > 2 * DAMON_MIN_REGION; i++) {
964 			/*
965 			 * Randomly select size of left sub-region to be at
966 			 * least 10 percent and at most 90% of original region
967 			 */
968 			sz_sub = ALIGN_DOWN(damon_rand(1, 10) *
969 					sz_region / 10, DAMON_MIN_REGION);
970 			/* Do not allow blank region */
971 			if (sz_sub == 0 || sz_sub >= sz_region)
972 				continue;
973 
974 			damon_split_region_at(t, r, sz_sub);
975 			sz_region = sz_sub;
976 		}
977 	}
978 }
979 
980 /*
981  * Split every target region into randomly-sized small regions
982  *
983  * This function splits every target region into random-sized small regions if
984  * current total number of the regions is equal or smaller than half of the
985  * user-specified maximum number of regions.  This is for maximizing the
986  * monitoring accuracy under the dynamically changeable access patterns.  If a
987  * split was unnecessarily made, later 'kdamond_merge_regions()' will revert
988  * it.
989  */
kdamond_split_regions(struct damon_ctx * ctx)990 static void kdamond_split_regions(struct damon_ctx *ctx)
991 {
992 	struct damon_target *t;
993 	unsigned int nr_regions = 0;
994 	static unsigned int last_nr_regions;
995 	int nr_subregions = 2;
996 
997 	damon_for_each_target(t, ctx)
998 		nr_regions += damon_nr_regions(t);
999 
1000 	if (nr_regions > ctx->attrs.max_nr_regions / 2)
1001 		return;
1002 
1003 	/* Maybe the middle of the region has different access frequency */
1004 	if (last_nr_regions == nr_regions &&
1005 			nr_regions < ctx->attrs.max_nr_regions / 3)
1006 		nr_subregions = 3;
1007 
1008 	damon_for_each_target(t, ctx)
1009 		damon_split_regions_of(t, nr_subregions);
1010 
1011 	last_nr_regions = nr_regions;
1012 }
1013 
1014 /*
1015  * Check whether it is time to check and apply the operations-related data
1016  * structures.
1017  *
1018  * Returns true if it is.
1019  */
kdamond_need_update_operations(struct damon_ctx * ctx)1020 static bool kdamond_need_update_operations(struct damon_ctx *ctx)
1021 {
1022 	return damon_check_reset_time_interval(&ctx->last_ops_update,
1023 			ctx->attrs.ops_update_interval);
1024 }
1025 
1026 /*
1027  * Check whether current monitoring should be stopped
1028  *
1029  * The monitoring is stopped when either the user requested to stop, or all
1030  * monitoring targets are invalid.
1031  *
1032  * Returns true if need to stop current monitoring.
1033  */
kdamond_need_stop(struct damon_ctx * ctx)1034 static bool kdamond_need_stop(struct damon_ctx *ctx)
1035 {
1036 	struct damon_target *t;
1037 
1038 	if (kthread_should_stop())
1039 		return true;
1040 
1041 	if (!ctx->ops.target_valid)
1042 		return false;
1043 
1044 	damon_for_each_target(t, ctx) {
1045 		if (ctx->ops.target_valid(t))
1046 			return false;
1047 	}
1048 
1049 	return true;
1050 }
1051 
damos_wmark_metric_value(enum damos_wmark_metric metric)1052 static unsigned long damos_wmark_metric_value(enum damos_wmark_metric metric)
1053 {
1054 	struct sysinfo i;
1055 
1056 	switch (metric) {
1057 	case DAMOS_WMARK_FREE_MEM_RATE:
1058 		si_meminfo(&i);
1059 		return i.freeram * 1000 / i.totalram;
1060 	default:
1061 		break;
1062 	}
1063 	return -EINVAL;
1064 }
1065 
1066 /*
1067  * Returns zero if the scheme is active.  Else, returns time to wait for next
1068  * watermark check in micro-seconds.
1069  */
damos_wmark_wait_us(struct damos * scheme)1070 static unsigned long damos_wmark_wait_us(struct damos *scheme)
1071 {
1072 	unsigned long metric;
1073 
1074 	if (scheme->wmarks.metric == DAMOS_WMARK_NONE)
1075 		return 0;
1076 
1077 	metric = damos_wmark_metric_value(scheme->wmarks.metric);
1078 	/* higher than high watermark or lower than low watermark */
1079 	if (metric > scheme->wmarks.high || scheme->wmarks.low > metric) {
1080 		if (scheme->wmarks.activated)
1081 			pr_debug("deactivate a scheme (%d) for %s wmark\n",
1082 					scheme->action,
1083 					metric > scheme->wmarks.high ?
1084 					"high" : "low");
1085 		scheme->wmarks.activated = false;
1086 		return scheme->wmarks.interval;
1087 	}
1088 
1089 	/* inactive and higher than middle watermark */
1090 	if ((scheme->wmarks.high >= metric && metric >= scheme->wmarks.mid) &&
1091 			!scheme->wmarks.activated)
1092 		return scheme->wmarks.interval;
1093 
1094 	if (!scheme->wmarks.activated)
1095 		pr_debug("activate a scheme (%d)\n", scheme->action);
1096 	scheme->wmarks.activated = true;
1097 	return 0;
1098 }
1099 
kdamond_usleep(unsigned long usecs)1100 static void kdamond_usleep(unsigned long usecs)
1101 {
1102 	/* See Documentation/timers/timers-howto.rst for the thresholds */
1103 	if (usecs > 20 * USEC_PER_MSEC)
1104 		schedule_timeout_idle(usecs_to_jiffies(usecs));
1105 	else
1106 		usleep_idle_range(usecs, usecs + 1);
1107 }
1108 
1109 /* Returns negative error code if it's not activated but should return */
kdamond_wait_activation(struct damon_ctx * ctx)1110 static int kdamond_wait_activation(struct damon_ctx *ctx)
1111 {
1112 	struct damos *s;
1113 	unsigned long wait_time;
1114 	unsigned long min_wait_time = 0;
1115 	bool init_wait_time = false;
1116 
1117 	while (!kdamond_need_stop(ctx)) {
1118 		damon_for_each_scheme(s, ctx) {
1119 			wait_time = damos_wmark_wait_us(s);
1120 			if (!init_wait_time || wait_time < min_wait_time) {
1121 				init_wait_time = true;
1122 				min_wait_time = wait_time;
1123 			}
1124 		}
1125 		if (!min_wait_time)
1126 			return 0;
1127 
1128 		kdamond_usleep(min_wait_time);
1129 
1130 		if (ctx->callback.after_wmarks_check &&
1131 				ctx->callback.after_wmarks_check(ctx))
1132 			break;
1133 	}
1134 	return -EBUSY;
1135 }
1136 
1137 /*
1138  * The monitoring daemon that runs as a kernel thread
1139  */
kdamond_fn(void * data)1140 static int kdamond_fn(void *data)
1141 {
1142 	struct damon_ctx *ctx = data;
1143 	struct damon_target *t;
1144 	struct damon_region *r, *next;
1145 	unsigned int max_nr_accesses = 0;
1146 	unsigned long sz_limit = 0;
1147 
1148 	pr_debug("kdamond (%d) starts\n", current->pid);
1149 
1150 	if (ctx->ops.init)
1151 		ctx->ops.init(ctx);
1152 	if (ctx->callback.before_start && ctx->callback.before_start(ctx))
1153 		goto done;
1154 
1155 	sz_limit = damon_region_sz_limit(ctx);
1156 
1157 	while (!kdamond_need_stop(ctx)) {
1158 		if (kdamond_wait_activation(ctx))
1159 			break;
1160 
1161 		if (ctx->ops.prepare_access_checks)
1162 			ctx->ops.prepare_access_checks(ctx);
1163 		if (ctx->callback.after_sampling &&
1164 				ctx->callback.after_sampling(ctx))
1165 			break;
1166 
1167 		kdamond_usleep(ctx->attrs.sample_interval);
1168 
1169 		if (ctx->ops.check_accesses)
1170 			max_nr_accesses = ctx->ops.check_accesses(ctx);
1171 
1172 		if (kdamond_aggregate_interval_passed(ctx)) {
1173 			kdamond_merge_regions(ctx,
1174 					max_nr_accesses / 10,
1175 					sz_limit);
1176 			if (ctx->callback.after_aggregation &&
1177 					ctx->callback.after_aggregation(ctx))
1178 				break;
1179 			kdamond_apply_schemes(ctx);
1180 			kdamond_reset_aggregated(ctx);
1181 			kdamond_split_regions(ctx);
1182 			if (ctx->ops.reset_aggregated)
1183 				ctx->ops.reset_aggregated(ctx);
1184 		}
1185 
1186 		if (kdamond_need_update_operations(ctx)) {
1187 			if (ctx->ops.update)
1188 				ctx->ops.update(ctx);
1189 			sz_limit = damon_region_sz_limit(ctx);
1190 		}
1191 	}
1192 done:
1193 	damon_for_each_target(t, ctx) {
1194 		damon_for_each_region_safe(r, next, t)
1195 			damon_destroy_region(r, t);
1196 	}
1197 
1198 	if (ctx->callback.before_terminate)
1199 		ctx->callback.before_terminate(ctx);
1200 	if (ctx->ops.cleanup)
1201 		ctx->ops.cleanup(ctx);
1202 
1203 	pr_debug("kdamond (%d) finishes\n", current->pid);
1204 	mutex_lock(&ctx->kdamond_lock);
1205 	ctx->kdamond = NULL;
1206 	mutex_unlock(&ctx->kdamond_lock);
1207 
1208 	mutex_lock(&damon_lock);
1209 	nr_running_ctxs--;
1210 	if (!nr_running_ctxs && running_exclusive_ctxs)
1211 		running_exclusive_ctxs = false;
1212 	mutex_unlock(&damon_lock);
1213 
1214 	return 0;
1215 }
1216 
1217 /*
1218  * struct damon_system_ram_region - System RAM resource address region of
1219  *				    [@start, @end).
1220  * @start:	Start address of the region (inclusive).
1221  * @end:	End address of the region (exclusive).
1222  */
1223 struct damon_system_ram_region {
1224 	unsigned long start;
1225 	unsigned long end;
1226 };
1227 
walk_system_ram(struct resource * res,void * arg)1228 static int walk_system_ram(struct resource *res, void *arg)
1229 {
1230 	struct damon_system_ram_region *a = arg;
1231 
1232 	if (a->end - a->start < resource_size(res)) {
1233 		a->start = res->start;
1234 		a->end = res->end;
1235 	}
1236 	return 0;
1237 }
1238 
1239 /*
1240  * Find biggest 'System RAM' resource and store its start and end address in
1241  * @start and @end, respectively.  If no System RAM is found, returns false.
1242  */
damon_find_biggest_system_ram(unsigned long * start,unsigned long * end)1243 static bool damon_find_biggest_system_ram(unsigned long *start,
1244 						unsigned long *end)
1245 
1246 {
1247 	struct damon_system_ram_region arg = {};
1248 
1249 	walk_system_ram_res(0, ULONG_MAX, &arg, walk_system_ram);
1250 	if (arg.end <= arg.start)
1251 		return false;
1252 
1253 	*start = arg.start;
1254 	*end = arg.end;
1255 	return true;
1256 }
1257 
1258 /**
1259  * damon_set_region_biggest_system_ram_default() - Set the region of the given
1260  * monitoring target as requested, or biggest 'System RAM'.
1261  * @t:		The monitoring target to set the region.
1262  * @start:	The pointer to the start address of the region.
1263  * @end:	The pointer to the end address of the region.
1264  *
1265  * This function sets the region of @t as requested by @start and @end.  If the
1266  * values of @start and @end are zero, however, this function finds the biggest
1267  * 'System RAM' resource and sets the region to cover the resource.  In the
1268  * latter case, this function saves the start and end addresses of the resource
1269  * in @start and @end, respectively.
1270  *
1271  * Return: 0 on success, negative error code otherwise.
1272  */
damon_set_region_biggest_system_ram_default(struct damon_target * t,unsigned long * start,unsigned long * end)1273 int damon_set_region_biggest_system_ram_default(struct damon_target *t,
1274 			unsigned long *start, unsigned long *end)
1275 {
1276 	struct damon_addr_range addr_range;
1277 
1278 	if (*start > *end)
1279 		return -EINVAL;
1280 
1281 	if (!*start && !*end &&
1282 		!damon_find_biggest_system_ram(start, end))
1283 		return -EINVAL;
1284 
1285 	addr_range.start = *start;
1286 	addr_range.end = *end;
1287 	return damon_set_regions(t, &addr_range, 1);
1288 }
1289 
damon_init(void)1290 static int __init damon_init(void)
1291 {
1292 	damon_region_cache = KMEM_CACHE(damon_region, 0);
1293 	if (unlikely(!damon_region_cache)) {
1294 		pr_err("creating damon_region_cache fails\n");
1295 		return -ENOMEM;
1296 	}
1297 
1298 	return 0;
1299 }
1300 
1301 subsys_initcall(damon_init);
1302 
1303 #include "core-test.h"
1304