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@xxxxxxxxxx>
---
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
