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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Common Primitives for Data Access Monitoring
4 *
5 * Author: SeongJae Park <sj@kernel.org>
6 */
7
8#include <linux/mmu_notifier.h>
9#include <linux/page_idle.h>
10#include <linux/pagemap.h>
11#include <linux/rmap.h>
12
13#include "ops-common.h"
14
15/*
16 * Get an online page for a pfn if it's in the LRU list. Otherwise, returns
17 * NULL.
18 *
19 * The body of this function is stolen from the 'page_idle_get_folio()'. We
20 * steal rather than reuse it because the code is quite simple.
21 */
22struct folio *damon_get_folio(unsigned long pfn)
23{
24 struct page *page = pfn_to_online_page(pfn);
25 struct folio *folio;
26
27 if (!page || PageTail(page))
28 return NULL;
29
30 folio = page_folio(page);
31 if (!folio_test_lru(folio) || !folio_try_get(folio))
32 return NULL;
33 if (unlikely(page_folio(page) != folio || !folio_test_lru(folio))) {
34 folio_put(folio);
35 folio = NULL;
36 }
37 return folio;
38}
39
40void damon_ptep_mkold(pte_t *pte, struct vm_area_struct *vma, unsigned long addr)
41{
42 struct folio *folio = damon_get_folio(pte_pfn(ptep_get(pte)));
43
44 if (!folio)
45 return;
46
47 if (ptep_clear_young_notify(vma, addr, pte))
48 folio_set_young(folio);
49
50 folio_set_idle(folio);
51 folio_put(folio);
52}
53
54void damon_pmdp_mkold(pmd_t *pmd, struct vm_area_struct *vma, unsigned long addr)
55{
56#ifdef CONFIG_TRANSPARENT_HUGEPAGE
57 struct folio *folio = damon_get_folio(pmd_pfn(pmdp_get(pmd)));
58
59 if (!folio)
60 return;
61
62 if (pmdp_clear_young_notify(vma, addr, pmd))
63 folio_set_young(folio);
64
65 folio_set_idle(folio);
66 folio_put(folio);
67#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
68}
69
70#define DAMON_MAX_SUBSCORE (100)
71#define DAMON_MAX_AGE_IN_LOG (32)
72
73int damon_hot_score(struct damon_ctx *c, struct damon_region *r,
74 struct damos *s)
75{
76 int freq_subscore;
77 unsigned int age_in_sec;
78 int age_in_log, age_subscore;
79 unsigned int freq_weight = s->quota.weight_nr_accesses;
80 unsigned int age_weight = s->quota.weight_age;
81 int hotness;
82
83 freq_subscore = r->nr_accesses * DAMON_MAX_SUBSCORE /
84 damon_max_nr_accesses(&c->attrs);
85
86 age_in_sec = (unsigned long)r->age * c->attrs.aggr_interval / 1000000;
87 for (age_in_log = 0; age_in_log < DAMON_MAX_AGE_IN_LOG && age_in_sec;
88 age_in_log++, age_in_sec >>= 1)
89 ;
90
91 /* If frequency is 0, higher age means it's colder */
92 if (freq_subscore == 0)
93 age_in_log *= -1;
94
95 /*
96 * Now age_in_log is in [-DAMON_MAX_AGE_IN_LOG, DAMON_MAX_AGE_IN_LOG].
97 * Scale it to be in [0, 100] and set it as age subscore.
98 */
99 age_in_log += DAMON_MAX_AGE_IN_LOG;
100 age_subscore = age_in_log * DAMON_MAX_SUBSCORE /
101 DAMON_MAX_AGE_IN_LOG / 2;
102
103 hotness = (freq_weight * freq_subscore + age_weight * age_subscore);
104 if (freq_weight + age_weight)
105 hotness /= freq_weight + age_weight;
106 /*
107 * Transform it to fit in [0, DAMOS_MAX_SCORE]
108 */
109 hotness = hotness * DAMOS_MAX_SCORE / DAMON_MAX_SUBSCORE;
110
111 return hotness;
112}
113
114int damon_cold_score(struct damon_ctx *c, struct damon_region *r,
115 struct damos *s)
116{
117 int hotness = damon_hot_score(c, r, s);
118
119 /* Return coldness of the region */
120 return DAMOS_MAX_SCORE - hotness;
121}
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Common Primitives for Data Access Monitoring
4 *
5 * Author: SeongJae Park <sj@kernel.org>
6 */
7
8#include <linux/mmu_notifier.h>
9#include <linux/page_idle.h>
10#include <linux/pagemap.h>
11#include <linux/rmap.h>
12
13#include "ops-common.h"
14
15/*
16 * Get an online page for a pfn if it's in the LRU list. Otherwise, returns
17 * NULL.
18 *
19 * The body of this function is stolen from the 'page_idle_get_page()'. We
20 * steal rather than reuse it because the code is quite simple.
21 */
22struct page *damon_get_page(unsigned long pfn)
23{
24 struct page *page = pfn_to_online_page(pfn);
25
26 if (!page || !PageLRU(page) || !get_page_unless_zero(page))
27 return NULL;
28
29 if (unlikely(!PageLRU(page))) {
30 put_page(page);
31 page = NULL;
32 }
33 return page;
34}
35
36void damon_ptep_mkold(pte_t *pte, struct mm_struct *mm, unsigned long addr)
37{
38 bool referenced = false;
39 struct page *page = damon_get_page(pte_pfn(*pte));
40
41 if (!page)
42 return;
43
44 if (pte_young(*pte)) {
45 referenced = true;
46 *pte = pte_mkold(*pte);
47 }
48
49#ifdef CONFIG_MMU_NOTIFIER
50 if (mmu_notifier_clear_young(mm, addr, addr + PAGE_SIZE))
51 referenced = true;
52#endif /* CONFIG_MMU_NOTIFIER */
53
54 if (referenced)
55 set_page_young(page);
56
57 set_page_idle(page);
58 put_page(page);
59}
60
61void damon_pmdp_mkold(pmd_t *pmd, struct mm_struct *mm, unsigned long addr)
62{
63#ifdef CONFIG_TRANSPARENT_HUGEPAGE
64 bool referenced = false;
65 struct page *page = damon_get_page(pmd_pfn(*pmd));
66
67 if (!page)
68 return;
69
70 if (pmd_young(*pmd)) {
71 referenced = true;
72 *pmd = pmd_mkold(*pmd);
73 }
74
75#ifdef CONFIG_MMU_NOTIFIER
76 if (mmu_notifier_clear_young(mm, addr, addr + HPAGE_PMD_SIZE))
77 referenced = true;
78#endif /* CONFIG_MMU_NOTIFIER */
79
80 if (referenced)
81 set_page_young(page);
82
83 set_page_idle(page);
84 put_page(page);
85#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
86}
87
88#define DAMON_MAX_SUBSCORE (100)
89#define DAMON_MAX_AGE_IN_LOG (32)
90
91int damon_hot_score(struct damon_ctx *c, struct damon_region *r,
92 struct damos *s)
93{
94 unsigned int max_nr_accesses;
95 int freq_subscore;
96 unsigned int age_in_sec;
97 int age_in_log, age_subscore;
98 unsigned int freq_weight = s->quota.weight_nr_accesses;
99 unsigned int age_weight = s->quota.weight_age;
100 int hotness;
101
102 max_nr_accesses = c->attrs.aggr_interval / c->attrs.sample_interval;
103 freq_subscore = r->nr_accesses * DAMON_MAX_SUBSCORE / max_nr_accesses;
104
105 age_in_sec = (unsigned long)r->age * c->attrs.aggr_interval / 1000000;
106 for (age_in_log = 0; age_in_log < DAMON_MAX_AGE_IN_LOG && age_in_sec;
107 age_in_log++, age_in_sec >>= 1)
108 ;
109
110 /* If frequency is 0, higher age means it's colder */
111 if (freq_subscore == 0)
112 age_in_log *= -1;
113
114 /*
115 * Now age_in_log is in [-DAMON_MAX_AGE_IN_LOG, DAMON_MAX_AGE_IN_LOG].
116 * Scale it to be in [0, 100] and set it as age subscore.
117 */
118 age_in_log += DAMON_MAX_AGE_IN_LOG;
119 age_subscore = age_in_log * DAMON_MAX_SUBSCORE /
120 DAMON_MAX_AGE_IN_LOG / 2;
121
122 hotness = (freq_weight * freq_subscore + age_weight * age_subscore);
123 if (freq_weight + age_weight)
124 hotness /= freq_weight + age_weight;
125 /*
126 * Transform it to fit in [0, DAMOS_MAX_SCORE]
127 */
128 hotness = hotness * DAMOS_MAX_SCORE / DAMON_MAX_SUBSCORE;
129
130 return hotness;
131}
132
133int damon_cold_score(struct damon_ctx *c, struct damon_region *r,
134 struct damos *s)
135{
136 int hotness = damon_hot_score(c, r, s);
137
138 /* Return coldness of the region */
139 return DAMOS_MAX_SCORE - hotness;
140}