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 "prmtv-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 */
damon_get_page(unsigned long pfn)22 struct 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
damon_ptep_mkold(pte_t * pte,struct mm_struct * mm,unsigned long addr)36 void 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
damon_pmdp_mkold(pmd_t * pmd,struct mm_struct * mm,unsigned long addr)61 void 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,
77 addr + ((1UL) << HPAGE_PMD_SHIFT)))
78 referenced = true;
79 #endif /* CONFIG_MMU_NOTIFIER */
80
81 if (referenced)
82 set_page_young(page);
83
84 set_page_idle(page);
85 put_page(page);
86 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
87 }
88
89 #define DAMON_MAX_SUBSCORE (100)
90 #define DAMON_MAX_AGE_IN_LOG (32)
91
damon_pageout_score(struct damon_ctx * c,struct damon_region * r,struct damos * s)92 int damon_pageout_score(struct damon_ctx *c, struct damon_region *r,
93 struct damos *s)
94 {
95 unsigned int max_nr_accesses;
96 int freq_subscore;
97 unsigned int age_in_sec;
98 int age_in_log, age_subscore;
99 unsigned int freq_weight = s->quota.weight_nr_accesses;
100 unsigned int age_weight = s->quota.weight_age;
101 int hotness;
102
103 max_nr_accesses = c->aggr_interval / c->sample_interval;
104 freq_subscore = r->nr_accesses * DAMON_MAX_SUBSCORE / max_nr_accesses;
105
106 age_in_sec = (unsigned long)r->age * c->aggr_interval / 1000000;
107 for (age_in_log = 0; age_in_log < DAMON_MAX_AGE_IN_LOG && age_in_sec;
108 age_in_log++, age_in_sec >>= 1)
109 ;
110
111 /* If frequency is 0, higher age means it's colder */
112 if (freq_subscore == 0)
113 age_in_log *= -1;
114
115 /*
116 * Now age_in_log is in [-DAMON_MAX_AGE_IN_LOG, DAMON_MAX_AGE_IN_LOG].
117 * Scale it to be in [0, 100] and set it as age subscore.
118 */
119 age_in_log += DAMON_MAX_AGE_IN_LOG;
120 age_subscore = age_in_log * DAMON_MAX_SUBSCORE /
121 DAMON_MAX_AGE_IN_LOG / 2;
122
123 hotness = (freq_weight * freq_subscore + age_weight * age_subscore);
124 if (freq_weight + age_weight)
125 hotness /= freq_weight + age_weight;
126 /*
127 * Transform it to fit in [0, DAMOS_MAX_SCORE]
128 */
129 hotness = hotness * DAMOS_MAX_SCORE / DAMON_MAX_SUBSCORE;
130
131 /* Return coldness of the region */
132 return DAMOS_MAX_SCORE - hotness;
133 }
134