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// SPDX-License-Identifier: GPL-2.0
/*
* Common Primitives for Data Access Monitoring
*
* Author: SeongJae Park <sj@kernel.org>
*/
#include <linux/mmu_notifier.h>
#include <linux/page_idle.h>
#include <linux/pagemap.h>
#include <linux/rmap.h>
#include "ops-common.h"
/*
* Get an online page for a pfn if it's in the LRU list. Otherwise, returns
* NULL.
*
* The body of this function is stolen from the 'page_idle_get_page()'. We
* steal rather than reuse it because the code is quite simple.
*/
struct page *damon_get_page(unsigned long pfn)
{
struct page *page = pfn_to_online_page(pfn);
if (!page || !PageLRU(page) || !get_page_unless_zero(page))
return NULL;
if (unlikely(!PageLRU(page))) {
put_page(page);
page = NULL;
}
return page;
}
void damon_ptep_mkold(pte_t *pte, struct mm_struct *mm, unsigned long addr)
{
bool referenced = false;
struct page *page = damon_get_page(pte_pfn(*pte));
if (!page)
return;
if (pte_young(*pte)) {
referenced = true;
*pte = pte_mkold(*pte);
}
#ifdef CONFIG_MMU_NOTIFIER
if (mmu_notifier_clear_young(mm, addr, addr + PAGE_SIZE))
referenced = true;
#endif /* CONFIG_MMU_NOTIFIER */
if (referenced)
set_page_young(page);
set_page_idle(page);
put_page(page);
}
void damon_pmdp_mkold(pmd_t *pmd, struct mm_struct *mm, unsigned long addr)
{
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
bool referenced = false;
struct page *page = damon_get_page(pmd_pfn(*pmd));
if (!page)
return;
if (pmd_young(*pmd)) {
referenced = true;
*pmd = pmd_mkold(*pmd);
}
#ifdef CONFIG_MMU_NOTIFIER
if (mmu_notifier_clear_young(mm, addr,
addr + ((1UL) << HPAGE_PMD_SHIFT)))
referenced = true;
#endif /* CONFIG_MMU_NOTIFIER */
if (referenced)
set_page_young(page);
set_page_idle(page);
put_page(page);
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
}
#define DAMON_MAX_SUBSCORE (100)
#define DAMON_MAX_AGE_IN_LOG (32)
int damon_pageout_score(struct damon_ctx *c, struct damon_region *r,
struct damos *s)
{
unsigned int max_nr_accesses;
int freq_subscore;
unsigned int age_in_sec;
int age_in_log, age_subscore;
unsigned int freq_weight = s->quota.weight_nr_accesses;
unsigned int age_weight = s->quota.weight_age;
int hotness;
max_nr_accesses = c->aggr_interval / c->sample_interval;
freq_subscore = r->nr_accesses * DAMON_MAX_SUBSCORE / max_nr_accesses;
age_in_sec = (unsigned long)r->age * c->aggr_interval / 1000000;
for (age_in_log = 0; age_in_log < DAMON_MAX_AGE_IN_LOG && age_in_sec;
age_in_log++, age_in_sec >>= 1)
;
/* If frequency is 0, higher age means it's colder */
if (freq_subscore == 0)
age_in_log *= -1;
/*
* Now age_in_log is in [-DAMON_MAX_AGE_IN_LOG, DAMON_MAX_AGE_IN_LOG].
* Scale it to be in [0, 100] and set it as age subscore.
*/
age_in_log += DAMON_MAX_AGE_IN_LOG;
age_subscore = age_in_log * DAMON_MAX_SUBSCORE /
DAMON_MAX_AGE_IN_LOG / 2;
hotness = (freq_weight * freq_subscore + age_weight * age_subscore);
if (freq_weight + age_weight)
hotness /= freq_weight + age_weight;
/*
* Transform it to fit in [0, DAMOS_MAX_SCORE]
*/
hotness = hotness * DAMOS_MAX_SCORE / DAMON_MAX_SUBSCORE;
/* Return coldness of the region */
return DAMOS_MAX_SCORE - hotness;
}
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