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 mm_struct *mm, unsigned long addr) 41 { 42 bool referenced = false; 43 struct folio *folio = damon_get_folio(pte_pfn(*pte)); 44 45 if (!folio) 46 return; 47 48 if (pte_young(*pte)) { 49 referenced = true; 50 *pte = pte_mkold(*pte); 51 } 52 53 #ifdef CONFIG_MMU_NOTIFIER 54 if (mmu_notifier_clear_young(mm, addr, addr + PAGE_SIZE)) 55 referenced = true; 56 #endif /* CONFIG_MMU_NOTIFIER */ 57 58 if (referenced) 59 folio_set_young(folio); 60 61 folio_set_idle(folio); 62 folio_put(folio); 63 } 64 65 void damon_pmdp_mkold(pmd_t *pmd, struct mm_struct *mm, unsigned long addr) 66 { 67 #ifdef CONFIG_TRANSPARENT_HUGEPAGE 68 bool referenced = false; 69 struct folio *folio = damon_get_folio(pmd_pfn(*pmd)); 70 71 if (!folio) 72 return; 73 74 if (pmd_young(*pmd)) { 75 referenced = true; 76 *pmd = pmd_mkold(*pmd); 77 } 78 79 #ifdef CONFIG_MMU_NOTIFIER 80 if (mmu_notifier_clear_young(mm, addr, addr + HPAGE_PMD_SIZE)) 81 referenced = true; 82 #endif /* CONFIG_MMU_NOTIFIER */ 83 84 if (referenced) 85 folio_set_young(folio); 86 87 folio_set_idle(folio); 88 folio_put(folio); 89 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */ 90 } 91 92 #define DAMON_MAX_SUBSCORE (100) 93 #define DAMON_MAX_AGE_IN_LOG (32) 94 95 int damon_hot_score(struct damon_ctx *c, struct damon_region *r, 96 struct damos *s) 97 { 98 unsigned int max_nr_accesses; 99 int freq_subscore; 100 unsigned int age_in_sec; 101 int age_in_log, age_subscore; 102 unsigned int freq_weight = s->quota.weight_nr_accesses; 103 unsigned int age_weight = s->quota.weight_age; 104 int hotness; 105 106 max_nr_accesses = c->attrs.aggr_interval / c->attrs.sample_interval; 107 freq_subscore = r->nr_accesses * DAMON_MAX_SUBSCORE / max_nr_accesses; 108 109 age_in_sec = (unsigned long)r->age * c->attrs.aggr_interval / 1000000; 110 for (age_in_log = 0; age_in_log < DAMON_MAX_AGE_IN_LOG && age_in_sec; 111 age_in_log++, age_in_sec >>= 1) 112 ; 113 114 /* If frequency is 0, higher age means it's colder */ 115 if (freq_subscore == 0) 116 age_in_log *= -1; 117 118 /* 119 * Now age_in_log is in [-DAMON_MAX_AGE_IN_LOG, DAMON_MAX_AGE_IN_LOG]. 120 * Scale it to be in [0, 100] and set it as age subscore. 121 */ 122 age_in_log += DAMON_MAX_AGE_IN_LOG; 123 age_subscore = age_in_log * DAMON_MAX_SUBSCORE / 124 DAMON_MAX_AGE_IN_LOG / 2; 125 126 hotness = (freq_weight * freq_subscore + age_weight * age_subscore); 127 if (freq_weight + age_weight) 128 hotness /= freq_weight + age_weight; 129 /* 130 * Transform it to fit in [0, DAMOS_MAX_SCORE] 131 */ 132 hotness = hotness * DAMOS_MAX_SCORE / DAMON_MAX_SUBSCORE; 133 134 return hotness; 135 } 136 137 int damon_cold_score(struct damon_ctx *c, struct damon_region *r, 138 struct damos *s) 139 { 140 int hotness = damon_hot_score(c, r, s); 141 142 /* Return coldness of the region */ 143 return DAMOS_MAX_SCORE - hotness; 144 } 145