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(pte_pfn(ptep_get(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(pmd_pfn(pmdp_get(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 unsigned int max_nr_accesses; 77 int freq_subscore; 78 unsigned int age_in_sec; 79 int age_in_log, age_subscore; 80 unsigned int freq_weight = s->quota.weight_nr_accesses; 81 unsigned int age_weight = s->quota.weight_age; 82 int hotness; 83 84 max_nr_accesses = c->attrs.aggr_interval / c->attrs.sample_interval; 85 freq_subscore = r->nr_accesses * DAMON_MAX_SUBSCORE / max_nr_accesses; 86 87 age_in_sec = (unsigned long)r->age * c->attrs.aggr_interval / 1000000; 88 for (age_in_log = 0; age_in_log < DAMON_MAX_AGE_IN_LOG && age_in_sec; 89 age_in_log++, age_in_sec >>= 1) 90 ; 91 92 /* If frequency is 0, higher age means it's colder */ 93 if (freq_subscore == 0) 94 age_in_log *= -1; 95 96 /* 97 * Now age_in_log is in [-DAMON_MAX_AGE_IN_LOG, DAMON_MAX_AGE_IN_LOG]. 98 * Scale it to be in [0, 100] and set it as age subscore. 99 */ 100 age_in_log += DAMON_MAX_AGE_IN_LOG; 101 age_subscore = age_in_log * DAMON_MAX_SUBSCORE / 102 DAMON_MAX_AGE_IN_LOG / 2; 103 104 hotness = (freq_weight * freq_subscore + age_weight * age_subscore); 105 if (freq_weight + age_weight) 106 hotness /= freq_weight + age_weight; 107 /* 108 * Transform it to fit in [0, DAMOS_MAX_SCORE] 109 */ 110 hotness = hotness * DAMOS_MAX_SCORE / DAMON_MAX_SUBSCORE; 111 112 return hotness; 113 } 114 115 int damon_cold_score(struct damon_ctx *c, struct damon_region *r, 116 struct damos *s) 117 { 118 int hotness = damon_hot_score(c, r, s); 119 120 /* Return coldness of the region */ 121 return DAMOS_MAX_SCORE - hotness; 122 } 123