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 */ 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 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 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, 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 91 int damon_pageout_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->aggr_interval / c->sample_interval; 103 freq_subscore = r->nr_accesses * DAMON_MAX_SUBSCORE / max_nr_accesses; 104 105 age_in_sec = (unsigned long)r->age * c->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 coldness of the region */ 131 return DAMOS_MAX_SCORE - hotness; 132 } 133