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 | */ |
22 | struct 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 | |
40 | void damon_ptep_mkold(pte_t *pte, struct vm_area_struct *vma, unsigned long addr) |
41 | { |
42 | struct folio *folio = damon_get_folio(pfn: pte_pfn(pte: ptep_get(ptep: 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 | |
54 | void 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(pfn: pmd_pfn(pmd: pmdp_get(pmdp: 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 | |
73 | int 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(attrs: &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 | |
114 | int 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 | } |
122 | |