1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0
2*4882a593Smuzhiyun /*
3*4882a593Smuzhiyun * Common Primitives for Data Access Monitoring
4*4882a593Smuzhiyun *
5*4882a593Smuzhiyun * Author: SeongJae Park <sj@kernel.org>
6*4882a593Smuzhiyun */
7*4882a593Smuzhiyun
8*4882a593Smuzhiyun #include <linux/mmu_notifier.h>
9*4882a593Smuzhiyun #include <linux/page_idle.h>
10*4882a593Smuzhiyun #include <linux/pagemap.h>
11*4882a593Smuzhiyun #include <linux/rmap.h>
12*4882a593Smuzhiyun
13*4882a593Smuzhiyun #include "prmtv-common.h"
14*4882a593Smuzhiyun
15*4882a593Smuzhiyun /*
16*4882a593Smuzhiyun * Get an online page for a pfn if it's in the LRU list. Otherwise, returns
17*4882a593Smuzhiyun * NULL.
18*4882a593Smuzhiyun *
19*4882a593Smuzhiyun * The body of this function is stolen from the 'page_idle_get_page()'. We
20*4882a593Smuzhiyun * steal rather than reuse it because the code is quite simple.
21*4882a593Smuzhiyun */
damon_get_page(unsigned long pfn)22*4882a593Smuzhiyun struct page *damon_get_page(unsigned long pfn)
23*4882a593Smuzhiyun {
24*4882a593Smuzhiyun struct page *page = pfn_to_online_page(pfn);
25*4882a593Smuzhiyun
26*4882a593Smuzhiyun if (!page || !PageLRU(page) || !get_page_unless_zero(page))
27*4882a593Smuzhiyun return NULL;
28*4882a593Smuzhiyun
29*4882a593Smuzhiyun if (unlikely(!PageLRU(page))) {
30*4882a593Smuzhiyun put_page(page);
31*4882a593Smuzhiyun page = NULL;
32*4882a593Smuzhiyun }
33*4882a593Smuzhiyun return page;
34*4882a593Smuzhiyun }
35*4882a593Smuzhiyun
damon_ptep_mkold(pte_t * pte,struct mm_struct * mm,unsigned long addr)36*4882a593Smuzhiyun void damon_ptep_mkold(pte_t *pte, struct mm_struct *mm, unsigned long addr)
37*4882a593Smuzhiyun {
38*4882a593Smuzhiyun bool referenced = false;
39*4882a593Smuzhiyun struct page *page = damon_get_page(pte_pfn(*pte));
40*4882a593Smuzhiyun
41*4882a593Smuzhiyun if (!page)
42*4882a593Smuzhiyun return;
43*4882a593Smuzhiyun
44*4882a593Smuzhiyun if (pte_young(*pte)) {
45*4882a593Smuzhiyun referenced = true;
46*4882a593Smuzhiyun *pte = pte_mkold(*pte);
47*4882a593Smuzhiyun }
48*4882a593Smuzhiyun
49*4882a593Smuzhiyun #ifdef CONFIG_MMU_NOTIFIER
50*4882a593Smuzhiyun if (mmu_notifier_clear_young(mm, addr, addr + PAGE_SIZE))
51*4882a593Smuzhiyun referenced = true;
52*4882a593Smuzhiyun #endif /* CONFIG_MMU_NOTIFIER */
53*4882a593Smuzhiyun
54*4882a593Smuzhiyun if (referenced)
55*4882a593Smuzhiyun set_page_young(page);
56*4882a593Smuzhiyun
57*4882a593Smuzhiyun set_page_idle(page);
58*4882a593Smuzhiyun put_page(page);
59*4882a593Smuzhiyun }
60*4882a593Smuzhiyun
damon_pmdp_mkold(pmd_t * pmd,struct mm_struct * mm,unsigned long addr)61*4882a593Smuzhiyun void damon_pmdp_mkold(pmd_t *pmd, struct mm_struct *mm, unsigned long addr)
62*4882a593Smuzhiyun {
63*4882a593Smuzhiyun #ifdef CONFIG_TRANSPARENT_HUGEPAGE
64*4882a593Smuzhiyun bool referenced = false;
65*4882a593Smuzhiyun struct page *page = damon_get_page(pmd_pfn(*pmd));
66*4882a593Smuzhiyun
67*4882a593Smuzhiyun if (!page)
68*4882a593Smuzhiyun return;
69*4882a593Smuzhiyun
70*4882a593Smuzhiyun if (pmd_young(*pmd)) {
71*4882a593Smuzhiyun referenced = true;
72*4882a593Smuzhiyun *pmd = pmd_mkold(*pmd);
73*4882a593Smuzhiyun }
74*4882a593Smuzhiyun
75*4882a593Smuzhiyun #ifdef CONFIG_MMU_NOTIFIER
76*4882a593Smuzhiyun if (mmu_notifier_clear_young(mm, addr,
77*4882a593Smuzhiyun addr + ((1UL) << HPAGE_PMD_SHIFT)))
78*4882a593Smuzhiyun referenced = true;
79*4882a593Smuzhiyun #endif /* CONFIG_MMU_NOTIFIER */
80*4882a593Smuzhiyun
81*4882a593Smuzhiyun if (referenced)
82*4882a593Smuzhiyun set_page_young(page);
83*4882a593Smuzhiyun
84*4882a593Smuzhiyun set_page_idle(page);
85*4882a593Smuzhiyun put_page(page);
86*4882a593Smuzhiyun #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
87*4882a593Smuzhiyun }
88*4882a593Smuzhiyun
89*4882a593Smuzhiyun #define DAMON_MAX_SUBSCORE (100)
90*4882a593Smuzhiyun #define DAMON_MAX_AGE_IN_LOG (32)
91*4882a593Smuzhiyun
damon_pageout_score(struct damon_ctx * c,struct damon_region * r,struct damos * s)92*4882a593Smuzhiyun int damon_pageout_score(struct damon_ctx *c, struct damon_region *r,
93*4882a593Smuzhiyun struct damos *s)
94*4882a593Smuzhiyun {
95*4882a593Smuzhiyun unsigned int max_nr_accesses;
96*4882a593Smuzhiyun int freq_subscore;
97*4882a593Smuzhiyun unsigned int age_in_sec;
98*4882a593Smuzhiyun int age_in_log, age_subscore;
99*4882a593Smuzhiyun unsigned int freq_weight = s->quota.weight_nr_accesses;
100*4882a593Smuzhiyun unsigned int age_weight = s->quota.weight_age;
101*4882a593Smuzhiyun int hotness;
102*4882a593Smuzhiyun
103*4882a593Smuzhiyun max_nr_accesses = c->aggr_interval / c->sample_interval;
104*4882a593Smuzhiyun freq_subscore = r->nr_accesses * DAMON_MAX_SUBSCORE / max_nr_accesses;
105*4882a593Smuzhiyun
106*4882a593Smuzhiyun age_in_sec = (unsigned long)r->age * c->aggr_interval / 1000000;
107*4882a593Smuzhiyun for (age_in_log = 0; age_in_log < DAMON_MAX_AGE_IN_LOG && age_in_sec;
108*4882a593Smuzhiyun age_in_log++, age_in_sec >>= 1)
109*4882a593Smuzhiyun ;
110*4882a593Smuzhiyun
111*4882a593Smuzhiyun /* If frequency is 0, higher age means it's colder */
112*4882a593Smuzhiyun if (freq_subscore == 0)
113*4882a593Smuzhiyun age_in_log *= -1;
114*4882a593Smuzhiyun
115*4882a593Smuzhiyun /*
116*4882a593Smuzhiyun * Now age_in_log is in [-DAMON_MAX_AGE_IN_LOG, DAMON_MAX_AGE_IN_LOG].
117*4882a593Smuzhiyun * Scale it to be in [0, 100] and set it as age subscore.
118*4882a593Smuzhiyun */
119*4882a593Smuzhiyun age_in_log += DAMON_MAX_AGE_IN_LOG;
120*4882a593Smuzhiyun age_subscore = age_in_log * DAMON_MAX_SUBSCORE /
121*4882a593Smuzhiyun DAMON_MAX_AGE_IN_LOG / 2;
122*4882a593Smuzhiyun
123*4882a593Smuzhiyun hotness = (freq_weight * freq_subscore + age_weight * age_subscore);
124*4882a593Smuzhiyun if (freq_weight + age_weight)
125*4882a593Smuzhiyun hotness /= freq_weight + age_weight;
126*4882a593Smuzhiyun /*
127*4882a593Smuzhiyun * Transform it to fit in [0, DAMOS_MAX_SCORE]
128*4882a593Smuzhiyun */
129*4882a593Smuzhiyun hotness = hotness * DAMOS_MAX_SCORE / DAMON_MAX_SUBSCORE;
130*4882a593Smuzhiyun
131*4882a593Smuzhiyun /* Return coldness of the region */
132*4882a593Smuzhiyun return DAMOS_MAX_SCORE - hotness;
133*4882a593Smuzhiyun }
134