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Message-Id: <20220513150000.25797-3-sj@kernel.org>
Date: Fri, 13 May 2022 16:59:59 +0200
From: SeongJae Park <sj@...nel.org>
To: unlisted-recipients:; (no To-header on input)
Cc: linux-damon@...zon.com, damon@...ts.linux.dev, linux-mm@...ck.org,
linux-kernel@...r.kernel.org, SeongJae Park <sj@...nel.org>
Subject: [RFC PATCH 2/3] mm/damon/schemes: Support 'hot' action
This commit adds another DAMOS action called 'hot'. The action marks
pages in the memory area of the taregt access pattern to be marked as
accessed. Specifically, calls 'mark_page_accessed()'. This is supposed
to be used for memory regions having frequent access so that hot pages
could be more protected under memory pressure.
Signed-off-by: SeongJae Park <sj@...nel.org>
---
include/linux/damon.h | 2 ++
mm/damon/ops-common.c | 42 ++++++++++++++++++++++++++++++++++++++++++
mm/damon/ops-common.h | 2 ++
mm/damon/paddr.c | 20 ++++++++++++++++++++
mm/damon/sysfs.c | 1 +
5 files changed, 67 insertions(+)
diff --git a/include/linux/damon.h b/include/linux/damon.h
index 7c62da31ce4b..ed5338c3133d 100644
--- a/include/linux/damon.h
+++ b/include/linux/damon.h
@@ -87,6 +87,7 @@ struct damon_target {
* @DAMOS_HUGEPAGE: Call ``madvise()`` for the region with MADV_HUGEPAGE.
* @DAMOS_NOHUGEPAGE: Call ``madvise()`` for the region with MADV_NOHUGEPAGE.
* @DAMOS_STAT: Do nothing but count the stat.
+ * @DAMOS_HOT: Mark the region as hot.
* @NR_DAMOS_ACTIONS: Total number of DAMOS actions
*/
enum damos_action {
@@ -96,6 +97,7 @@ enum damos_action {
DAMOS_HUGEPAGE,
DAMOS_NOHUGEPAGE,
DAMOS_STAT, /* Do nothing but only record the stat */
+ DAMOS_HOT,
NR_DAMOS_ACTIONS,
};
diff --git a/mm/damon/ops-common.c b/mm/damon/ops-common.c
index e346cc10d143..fe9288025bae 100644
--- a/mm/damon/ops-common.c
+++ b/mm/damon/ops-common.c
@@ -131,3 +131,45 @@ int damon_pageout_score(struct damon_ctx *c, struct damon_region *r,
/* Return coldness of the region */
return DAMOS_MAX_SCORE - hotness;
}
+
+int damon_hot_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 hotness;
+}
diff --git a/mm/damon/ops-common.h b/mm/damon/ops-common.h
index e790cb5f8fe0..52329ff361cd 100644
--- a/mm/damon/ops-common.h
+++ b/mm/damon/ops-common.h
@@ -14,3 +14,5 @@ void damon_pmdp_mkold(pmd_t *pmd, struct mm_struct *mm, unsigned long addr);
int damon_pageout_score(struct damon_ctx *c, struct damon_region *r,
struct damos *s);
+int damon_hot_score(struct damon_ctx *c, struct damon_region *r,
+ struct damos *s);
diff --git a/mm/damon/paddr.c b/mm/damon/paddr.c
index 08deee12ebfd..69980b922bf4 100644
--- a/mm/damon/paddr.c
+++ b/mm/damon/paddr.c
@@ -233,6 +233,22 @@ static unsigned long damon_pa_pageout(struct damon_region *r)
return applied * PAGE_SIZE;
}
+static unsigned long damon_pa_mark_accessed(struct damon_region *r)
+{
+ unsigned long addr, applied = 0;
+
+ for (addr = r->ar.start; addr < r->ar.end; addr += PAGE_SIZE) {
+ struct page *page = damon_get_page(PHYS_PFN(addr));
+
+ if (!page)
+ continue;
+ mark_page_accessed(page);
+ put_page(page);
+ applied++;
+ }
+ return applied * PAGE_SIZE;
+}
+
static unsigned long damon_pa_apply_scheme(struct damon_ctx *ctx,
struct damon_target *t, struct damon_region *r,
struct damos *scheme)
@@ -240,6 +256,8 @@ static unsigned long damon_pa_apply_scheme(struct damon_ctx *ctx,
switch (scheme->action) {
case DAMOS_PAGEOUT:
return damon_pa_pageout(r);
+ case DAMOS_HOT:
+ return damon_pa_mark_accessed(r);
default:
break;
}
@@ -253,6 +271,8 @@ static int damon_pa_scheme_score(struct damon_ctx *context,
switch (scheme->action) {
case DAMOS_PAGEOUT:
return damon_pageout_score(context, r, scheme);
+ case DAMOS_HOT:
+ return damon_hot_score(context, r, scheme);
default:
break;
}
diff --git a/mm/damon/sysfs.c b/mm/damon/sysfs.c
index 09f9e8ca3d1f..a1de2278f8c2 100644
--- a/mm/damon/sysfs.c
+++ b/mm/damon/sysfs.c
@@ -763,6 +763,7 @@ static const char * const damon_sysfs_damos_action_strs[] = {
"hugepage",
"nohugepage",
"stat",
+ "hot",
};
static struct damon_sysfs_scheme *damon_sysfs_scheme_alloc(
--
2.17.1
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