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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
25static DEFINE_MUTEX(damon_lock);
26static int nr_running_ctxs;
27static bool running_exclusive_ctxs;
28
29static DEFINE_MUTEX(damon_ops_lock);
30static struct damon_operations damon_registered_ops[NR_DAMON_OPS];
31
32static 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 */
35static 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 */
50bool 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 */
71int 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;
84out:
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 */
99int 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 */
120struct 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(®ion->list);
132
133 region->age = 0;
134 region->last_nr_accesses = 0;
135
136 return region;
137}
138
139void 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
145static void damon_del_region(struct damon_region *r, struct damon_target *t)
146{
147 list_del(&r->list);
148 t->nr_regions--;
149}
150
151static void damon_free_region(struct damon_region *r)
152{
153 kmem_cache_free(damon_region_cache, r);
154}
155
156void 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 */
167static 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 */
176static 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 */
208int 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 */
267static 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
279struct 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
301void damon_add_scheme(struct damon_ctx *ctx, struct damos *s)
302{
303 list_add_tail(&s->list, &ctx->schemes);
304}
305
306static void damon_del_scheme(struct damos *s)
307{
308 list_del(&s->list);
309}
310
311static void damon_free_scheme(struct damos *s)
312{
313 kfree(s);
314}
315
316void 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 */
327struct 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
343void damon_add_target(struct damon_ctx *ctx, struct damon_target *t)
344{
345 list_add_tail(&t->list, &ctx->adaptive_targets);
346}
347
348bool damon_targets_empty(struct damon_ctx *ctx)
349{
350 return list_empty(&ctx->adaptive_targets);
351}
352
353static void damon_del_target(struct damon_target *t)
354{
355 list_del(&t->list);
356}
357
358void 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
367void damon_destroy_target(struct damon_target *t)
368{
369 damon_del_target(t);
370 damon_free_target(t);
371}
372
373unsigned int damon_nr_regions(struct damon_target *t)
374{
375 return t->nr_regions;
376}
377
378struct 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
404static 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
417void 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 */
439int 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 */
459void 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 */
474int 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 */
486static 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
505static 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 */
515static 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 */
549int 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 */
580static 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 */
605int 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 */
628static 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 */
644static 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 */
653static 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
670static void damon_split_region_at(struct damon_target *t,
671 struct damon_region *r, unsigned long sz_r);
672
673static 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
686static 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
697/*
698 * damos_skip_charged_region() - Check if the given region or starting part of
699 * it is already charged for the DAMOS quota.
700 * @t: The target of the region.
701 * @rp: The pointer to the region.
702 * @s: The scheme to be applied.
703 *
704 * If a quota of a scheme has exceeded in a quota charge window, the scheme's
705 * action would applied to only a part of the target access pattern fulfilling
706 * regions. To avoid applying the scheme action to only already applied
707 * regions, DAMON skips applying the scheme action to the regions that charged
708 * in the previous charge window.
709 *
710 * This function checks if a given region should be skipped or not for the
711 * reason. If only the starting part of the region has previously charged,
712 * this function splits the region into two so that the second one covers the
713 * area that not charged in the previous charge widnow and saves the second
714 * region in *rp and returns false, so that the caller can apply DAMON action
715 * to the second one.
716 *
717 * Return: true if the region should be entirely skipped, false otherwise.
718 */
719static bool damos_skip_charged_region(struct damon_target *t,
720 struct damon_region **rp, struct damos *s)
721{
722 struct damon_region *r = *rp;
723 struct damos_quota *quota = &s->quota;
724 unsigned long sz_to_skip;
725
726 /* Skip previously charged regions */
727 if (quota->charge_target_from) {
728 if (t != quota->charge_target_from)
729 return true;
730 if (r == damon_last_region(t)) {
731 quota->charge_target_from = NULL;
732 quota->charge_addr_from = 0;
733 return true;
734 }
735 if (quota->charge_addr_from &&
736 r->ar.end <= quota->charge_addr_from)
737 return true;
738
739 if (quota->charge_addr_from && r->ar.start <
740 quota->charge_addr_from) {
741 sz_to_skip = ALIGN_DOWN(quota->charge_addr_from -
742 r->ar.start, DAMON_MIN_REGION);
743 if (!sz_to_skip) {
744 if (damon_sz_region(r) <= DAMON_MIN_REGION)
745 return true;
746 sz_to_skip = DAMON_MIN_REGION;
747 }
748 damon_split_region_at(t, r, sz_to_skip);
749 r = damon_next_region(r);
750 *rp = r;
751 }
752 quota->charge_target_from = NULL;
753 quota->charge_addr_from = 0;
754 }
755 return false;
756}
757
758static void damos_update_stat(struct damos *s,
759 unsigned long sz_tried, unsigned long sz_applied)
760{
761 s->stat.nr_tried++;
762 s->stat.sz_tried += sz_tried;
763 if (sz_applied)
764 s->stat.nr_applied++;
765 s->stat.sz_applied += sz_applied;
766}
767
768static void damos_apply_scheme(struct damon_ctx *c, struct damon_target *t,
769 struct damon_region *r, struct damos *s)
770{
771 struct damos_quota *quota = &s->quota;
772 unsigned long sz = damon_sz_region(r);
773 struct timespec64 begin, end;
774 unsigned long sz_applied = 0;
775 int err = 0;
776
777 if (c->ops.apply_scheme) {
778 if (quota->esz && quota->charged_sz + sz > quota->esz) {
779 sz = ALIGN_DOWN(quota->esz - quota->charged_sz,
780 DAMON_MIN_REGION);
781 if (!sz)
782 goto update_stat;
783 damon_split_region_at(t, r, sz);
784 }
785 ktime_get_coarse_ts64(&begin);
786 if (c->callback.before_damos_apply)
787 err = c->callback.before_damos_apply(c, t, r, s);
788 if (!err)
789 sz_applied = c->ops.apply_scheme(c, t, r, s);
790 ktime_get_coarse_ts64(&end);
791 quota->total_charged_ns += timespec64_to_ns(&end) -
792 timespec64_to_ns(&begin);
793 quota->charged_sz += sz;
794 if (quota->esz && quota->charged_sz >= quota->esz) {
795 quota->charge_target_from = t;
796 quota->charge_addr_from = r->ar.end + 1;
797 }
798 }
799 if (s->action != DAMOS_STAT)
800 r->age = 0;
801
802update_stat:
803 damos_update_stat(s, sz, sz_applied);
804}
805
806static void damon_do_apply_schemes(struct damon_ctx *c,
807 struct damon_target *t,
808 struct damon_region *r)
809{
810 struct damos *s;
811
812 damon_for_each_scheme(s, c) {
813 struct damos_quota *quota = &s->quota;
814
815 if (!s->wmarks.activated)
816 continue;
817
818 /* Check the quota */
819 if (quota->esz && quota->charged_sz >= quota->esz)
820 continue;
821
822 if (damos_skip_charged_region(t, &r, s))
823 continue;
824
825 if (!damos_valid_target(c, t, r, s))
826 continue;
827
828 damos_apply_scheme(c, t, r, s);
829 }
830}
831
832/* Shouldn't be called if quota->ms and quota->sz are zero */
833static void damos_set_effective_quota(struct damos_quota *quota)
834{
835 unsigned long throughput;
836 unsigned long esz;
837
838 if (!quota->ms) {
839 quota->esz = quota->sz;
840 return;
841 }
842
843 if (quota->total_charged_ns)
844 throughput = quota->total_charged_sz * 1000000 /
845 quota->total_charged_ns;
846 else
847 throughput = PAGE_SIZE * 1024;
848 esz = throughput * quota->ms;
849
850 if (quota->sz && quota->sz < esz)
851 esz = quota->sz;
852 quota->esz = esz;
853}
854
855static void damos_adjust_quota(struct damon_ctx *c, struct damos *s)
856{
857 struct damos_quota *quota = &s->quota;
858 struct damon_target *t;
859 struct damon_region *r;
860 unsigned long cumulated_sz;
861 unsigned int score, max_score = 0;
862
863 if (!quota->ms && !quota->sz)
864 return;
865
866 /* New charge window starts */
867 if (time_after_eq(jiffies, quota->charged_from +
868 msecs_to_jiffies(quota->reset_interval))) {
869 if (quota->esz && quota->charged_sz >= quota->esz)
870 s->stat.qt_exceeds++;
871 quota->total_charged_sz += quota->charged_sz;
872 quota->charged_from = jiffies;
873 quota->charged_sz = 0;
874 damos_set_effective_quota(quota);
875 }
876
877 if (!c->ops.get_scheme_score)
878 return;
879
880 /* Fill up the score histogram */
881 memset(quota->histogram, 0, sizeof(quota->histogram));
882 damon_for_each_target(t, c) {
883 damon_for_each_region(r, t) {
884 if (!__damos_valid_target(r, s))
885 continue;
886 score = c->ops.get_scheme_score(c, t, r, s);
887 quota->histogram[score] += damon_sz_region(r);
888 if (score > max_score)
889 max_score = score;
890 }
891 }
892
893 /* Set the min score limit */
894 for (cumulated_sz = 0, score = max_score; ; score--) {
895 cumulated_sz += quota->histogram[score];
896 if (cumulated_sz >= quota->esz || !score)
897 break;
898 }
899 quota->min_score = score;
900}
901
902static void kdamond_apply_schemes(struct damon_ctx *c)
903{
904 struct damon_target *t;
905 struct damon_region *r, *next_r;
906 struct damos *s;
907
908 damon_for_each_scheme(s, c) {
909 if (!s->wmarks.activated)
910 continue;
911
912 damos_adjust_quota(c, s);
913 }
914
915 damon_for_each_target(t, c) {
916 damon_for_each_region_safe(r, next_r, t)
917 damon_do_apply_schemes(c, t, r);
918 }
919}
920
921/*
922 * Merge two adjacent regions into one region
923 */
924static void damon_merge_two_regions(struct damon_target *t,
925 struct damon_region *l, struct damon_region *r)
926{
927 unsigned long sz_l = damon_sz_region(l), sz_r = damon_sz_region(r);
928
929 l->nr_accesses = (l->nr_accesses * sz_l + r->nr_accesses * sz_r) /
930 (sz_l + sz_r);
931 l->age = (l->age * sz_l + r->age * sz_r) / (sz_l + sz_r);
932 l->ar.end = r->ar.end;
933 damon_destroy_region(r, t);
934}
935
936/*
937 * Merge adjacent regions having similar access frequencies
938 *
939 * t target affected by this merge operation
940 * thres '->nr_accesses' diff threshold for the merge
941 * sz_limit size upper limit of each region
942 */
943static void damon_merge_regions_of(struct damon_target *t, unsigned int thres,
944 unsigned long sz_limit)
945{
946 struct damon_region *r, *prev = NULL, *next;
947
948 damon_for_each_region_safe(r, next, t) {
949 if (abs(r->nr_accesses - r->last_nr_accesses) > thres)
950 r->age = 0;
951 else
952 r->age++;
953
954 if (prev && prev->ar.end == r->ar.start &&
955 abs(prev->nr_accesses - r->nr_accesses) <= thres &&
956 damon_sz_region(prev) + damon_sz_region(r) <= sz_limit)
957 damon_merge_two_regions(t, prev, r);
958 else
959 prev = r;
960 }
961}
962
963/*
964 * Merge adjacent regions having similar access frequencies
965 *
966 * threshold '->nr_accesses' diff threshold for the merge
967 * sz_limit size upper limit of each region
968 *
969 * This function merges monitoring target regions which are adjacent and their
970 * access frequencies are similar. This is for minimizing the monitoring
971 * overhead under the dynamically changeable access pattern. If a merge was
972 * unnecessarily made, later 'kdamond_split_regions()' will revert it.
973 */
974static void kdamond_merge_regions(struct damon_ctx *c, unsigned int threshold,
975 unsigned long sz_limit)
976{
977 struct damon_target *t;
978
979 damon_for_each_target(t, c)
980 damon_merge_regions_of(t, threshold, sz_limit);
981}
982
983/*
984 * Split a region in two
985 *
986 * r the region to be split
987 * sz_r size of the first sub-region that will be made
988 */
989static void damon_split_region_at(struct damon_target *t,
990 struct damon_region *r, unsigned long sz_r)
991{
992 struct damon_region *new;
993
994 new = damon_new_region(r->ar.start + sz_r, r->ar.end);
995 if (!new)
996 return;
997
998 r->ar.end = new->ar.start;
999
1000 new->age = r->age;
1001 new->last_nr_accesses = r->last_nr_accesses;
1002
1003 damon_insert_region(new, r, damon_next_region(r), t);
1004}
1005
1006/* Split every region in the given target into 'nr_subs' regions */
1007static void damon_split_regions_of(struct damon_target *t, int nr_subs)
1008{
1009 struct damon_region *r, *next;
1010 unsigned long sz_region, sz_sub = 0;
1011 int i;
1012
1013 damon_for_each_region_safe(r, next, t) {
1014 sz_region = damon_sz_region(r);
1015
1016 for (i = 0; i < nr_subs - 1 &&
1017 sz_region > 2 * DAMON_MIN_REGION; i++) {
1018 /*
1019 * Randomly select size of left sub-region to be at
1020 * least 10 percent and at most 90% of original region
1021 */
1022 sz_sub = ALIGN_DOWN(damon_rand(1, 10) *
1023 sz_region / 10, DAMON_MIN_REGION);
1024 /* Do not allow blank region */
1025 if (sz_sub == 0 || sz_sub >= sz_region)
1026 continue;
1027
1028 damon_split_region_at(t, r, sz_sub);
1029 sz_region = sz_sub;
1030 }
1031 }
1032}
1033
1034/*
1035 * Split every target region into randomly-sized small regions
1036 *
1037 * This function splits every target region into random-sized small regions if
1038 * current total number of the regions is equal or smaller than half of the
1039 * user-specified maximum number of regions. This is for maximizing the
1040 * monitoring accuracy under the dynamically changeable access patterns. If a
1041 * split was unnecessarily made, later 'kdamond_merge_regions()' will revert
1042 * it.
1043 */
1044static void kdamond_split_regions(struct damon_ctx *ctx)
1045{
1046 struct damon_target *t;
1047 unsigned int nr_regions = 0;
1048 static unsigned int last_nr_regions;
1049 int nr_subregions = 2;
1050
1051 damon_for_each_target(t, ctx)
1052 nr_regions += damon_nr_regions(t);
1053
1054 if (nr_regions > ctx->attrs.max_nr_regions / 2)
1055 return;
1056
1057 /* Maybe the middle of the region has different access frequency */
1058 if (last_nr_regions == nr_regions &&
1059 nr_regions < ctx->attrs.max_nr_regions / 3)
1060 nr_subregions = 3;
1061
1062 damon_for_each_target(t, ctx)
1063 damon_split_regions_of(t, nr_subregions);
1064
1065 last_nr_regions = nr_regions;
1066}
1067
1068/*
1069 * Check whether it is time to check and apply the operations-related data
1070 * structures.
1071 *
1072 * Returns true if it is.
1073 */
1074static bool kdamond_need_update_operations(struct damon_ctx *ctx)
1075{
1076 return damon_check_reset_time_interval(&ctx->last_ops_update,
1077 ctx->attrs.ops_update_interval);
1078}
1079
1080/*
1081 * Check whether current monitoring should be stopped
1082 *
1083 * The monitoring is stopped when either the user requested to stop, or all
1084 * monitoring targets are invalid.
1085 *
1086 * Returns true if need to stop current monitoring.
1087 */
1088static bool kdamond_need_stop(struct damon_ctx *ctx)
1089{
1090 struct damon_target *t;
1091
1092 if (kthread_should_stop())
1093 return true;
1094
1095 if (!ctx->ops.target_valid)
1096 return false;
1097
1098 damon_for_each_target(t, ctx) {
1099 if (ctx->ops.target_valid(t))
1100 return false;
1101 }
1102
1103 return true;
1104}
1105
1106static unsigned long damos_wmark_metric_value(enum damos_wmark_metric metric)
1107{
1108 struct sysinfo i;
1109
1110 switch (metric) {
1111 case DAMOS_WMARK_FREE_MEM_RATE:
1112 si_meminfo(&i);
1113 return i.freeram * 1000 / i.totalram;
1114 default:
1115 break;
1116 }
1117 return -EINVAL;
1118}
1119
1120/*
1121 * Returns zero if the scheme is active. Else, returns time to wait for next
1122 * watermark check in micro-seconds.
1123 */
1124static unsigned long damos_wmark_wait_us(struct damos *scheme)
1125{
1126 unsigned long metric;
1127
1128 if (scheme->wmarks.metric == DAMOS_WMARK_NONE)
1129 return 0;
1130
1131 metric = damos_wmark_metric_value(scheme->wmarks.metric);
1132 /* higher than high watermark or lower than low watermark */
1133 if (metric > scheme->wmarks.high || scheme->wmarks.low > metric) {
1134 if (scheme->wmarks.activated)
1135 pr_debug("deactivate a scheme (%d) for %s wmark\n",
1136 scheme->action,
1137 metric > scheme->wmarks.high ?
1138 "high" : "low");
1139 scheme->wmarks.activated = false;
1140 return scheme->wmarks.interval;
1141 }
1142
1143 /* inactive and higher than middle watermark */
1144 if ((scheme->wmarks.high >= metric && metric >= scheme->wmarks.mid) &&
1145 !scheme->wmarks.activated)
1146 return scheme->wmarks.interval;
1147
1148 if (!scheme->wmarks.activated)
1149 pr_debug("activate a scheme (%d)\n", scheme->action);
1150 scheme->wmarks.activated = true;
1151 return 0;
1152}
1153
1154static void kdamond_usleep(unsigned long usecs)
1155{
1156 /* See Documentation/timers/timers-howto.rst for the thresholds */
1157 if (usecs > 20 * USEC_PER_MSEC)
1158 schedule_timeout_idle(usecs_to_jiffies(usecs));
1159 else
1160 usleep_idle_range(usecs, usecs + 1);
1161}
1162
1163/* Returns negative error code if it's not activated but should return */
1164static int kdamond_wait_activation(struct damon_ctx *ctx)
1165{
1166 struct damos *s;
1167 unsigned long wait_time;
1168 unsigned long min_wait_time = 0;
1169 bool init_wait_time = false;
1170
1171 while (!kdamond_need_stop(ctx)) {
1172 damon_for_each_scheme(s, ctx) {
1173 wait_time = damos_wmark_wait_us(s);
1174 if (!init_wait_time || wait_time < min_wait_time) {
1175 init_wait_time = true;
1176 min_wait_time = wait_time;
1177 }
1178 }
1179 if (!min_wait_time)
1180 return 0;
1181
1182 kdamond_usleep(min_wait_time);
1183
1184 if (ctx->callback.after_wmarks_check &&
1185 ctx->callback.after_wmarks_check(ctx))
1186 break;
1187 }
1188 return -EBUSY;
1189}
1190
1191/*
1192 * The monitoring daemon that runs as a kernel thread
1193 */
1194static int kdamond_fn(void *data)
1195{
1196 struct damon_ctx *ctx = data;
1197 struct damon_target *t;
1198 struct damon_region *r, *next;
1199 unsigned int max_nr_accesses = 0;
1200 unsigned long sz_limit = 0;
1201
1202 pr_debug("kdamond (%d) starts\n", current->pid);
1203
1204 if (ctx->ops.init)
1205 ctx->ops.init(ctx);
1206 if (ctx->callback.before_start && ctx->callback.before_start(ctx))
1207 goto done;
1208
1209 sz_limit = damon_region_sz_limit(ctx);
1210
1211 while (!kdamond_need_stop(ctx)) {
1212 if (kdamond_wait_activation(ctx))
1213 break;
1214
1215 if (ctx->ops.prepare_access_checks)
1216 ctx->ops.prepare_access_checks(ctx);
1217 if (ctx->callback.after_sampling &&
1218 ctx->callback.after_sampling(ctx))
1219 break;
1220
1221 kdamond_usleep(ctx->attrs.sample_interval);
1222
1223 if (ctx->ops.check_accesses)
1224 max_nr_accesses = ctx->ops.check_accesses(ctx);
1225
1226 if (kdamond_aggregate_interval_passed(ctx)) {
1227 kdamond_merge_regions(ctx,
1228 max_nr_accesses / 10,
1229 sz_limit);
1230 if (ctx->callback.after_aggregation &&
1231 ctx->callback.after_aggregation(ctx))
1232 break;
1233 kdamond_apply_schemes(ctx);
1234 kdamond_reset_aggregated(ctx);
1235 kdamond_split_regions(ctx);
1236 if (ctx->ops.reset_aggregated)
1237 ctx->ops.reset_aggregated(ctx);
1238 }
1239
1240 if (kdamond_need_update_operations(ctx)) {
1241 if (ctx->ops.update)
1242 ctx->ops.update(ctx);
1243 sz_limit = damon_region_sz_limit(ctx);
1244 }
1245 }
1246done:
1247 damon_for_each_target(t, ctx) {
1248 damon_for_each_region_safe(r, next, t)
1249 damon_destroy_region(r, t);
1250 }
1251
1252 if (ctx->callback.before_terminate)
1253 ctx->callback.before_terminate(ctx);
1254 if (ctx->ops.cleanup)
1255 ctx->ops.cleanup(ctx);
1256
1257 pr_debug("kdamond (%d) finishes\n", current->pid);
1258 mutex_lock(&ctx->kdamond_lock);
1259 ctx->kdamond = NULL;
1260 mutex_unlock(&ctx->kdamond_lock);
1261
1262 mutex_lock(&damon_lock);
1263 nr_running_ctxs--;
1264 if (!nr_running_ctxs && running_exclusive_ctxs)
1265 running_exclusive_ctxs = false;
1266 mutex_unlock(&damon_lock);
1267
1268 return 0;
1269}
1270
1271/*
1272 * struct damon_system_ram_region - System RAM resource address region of
1273 * [@start, @end).
1274 * @start: Start address of the region (inclusive).
1275 * @end: End address of the region (exclusive).
1276 */
1277struct damon_system_ram_region {
1278 unsigned long start;
1279 unsigned long end;
1280};
1281
1282static int walk_system_ram(struct resource *res, void *arg)
1283{
1284 struct damon_system_ram_region *a = arg;
1285
1286 if (a->end - a->start < resource_size(res)) {
1287 a->start = res->start;
1288 a->end = res->end;
1289 }
1290 return 0;
1291}
1292
1293/*
1294 * Find biggest 'System RAM' resource and store its start and end address in
1295 * @start and @end, respectively. If no System RAM is found, returns false.
1296 */
1297static bool damon_find_biggest_system_ram(unsigned long *start,
1298 unsigned long *end)
1299
1300{
1301 struct damon_system_ram_region arg = {};
1302
1303 walk_system_ram_res(0, ULONG_MAX, &arg, walk_system_ram);
1304 if (arg.end <= arg.start)
1305 return false;
1306
1307 *start = arg.start;
1308 *end = arg.end;
1309 return true;
1310}
1311
1312/**
1313 * damon_set_region_biggest_system_ram_default() - Set the region of the given
1314 * monitoring target as requested, or biggest 'System RAM'.
1315 * @t: The monitoring target to set the region.
1316 * @start: The pointer to the start address of the region.
1317 * @end: The pointer to the end address of the region.
1318 *
1319 * This function sets the region of @t as requested by @start and @end. If the
1320 * values of @start and @end are zero, however, this function finds the biggest
1321 * 'System RAM' resource and sets the region to cover the resource. In the
1322 * latter case, this function saves the start and end addresses of the resource
1323 * in @start and @end, respectively.
1324 *
1325 * Return: 0 on success, negative error code otherwise.
1326 */
1327int damon_set_region_biggest_system_ram_default(struct damon_target *t,
1328 unsigned long *start, unsigned long *end)
1329{
1330 struct damon_addr_range addr_range;
1331
1332 if (*start > *end)
1333 return -EINVAL;
1334
1335 if (!*start && !*end &&
1336 !damon_find_biggest_system_ram(start, end))
1337 return -EINVAL;
1338
1339 addr_range.start = *start;
1340 addr_range.end = *end;
1341 return damon_set_regions(t, &addr_range, 1);
1342}
1343
1344static int __init damon_init(void)
1345{
1346 damon_region_cache = KMEM_CACHE(damon_region, 0);
1347 if (unlikely(!damon_region_cache)) {
1348 pr_err("creating damon_region_cache fails\n");
1349 return -ENOMEM;
1350 }
1351
1352 return 0;
1353}
1354
1355subsys_initcall(damon_init);
1356
1357#include "core-test.h"