[PATCH v4 11/12] khugepaged: add per-order mTHP khugepaged stats

Nico Pache
2025-04-17T00:07:47Z

With mTHP support inplace, let add the per-order mTHP stats for
exceeding NONE, SWAP, and SHARED.

Signed-off-by: Nico Pache <npache@redhat.com>
---
include/linux/huge_mm.h | 3 +++
mm/huge_memory.c | 7 +++++++
mm/khugepaged.c | 16 +++++++++++++---
3 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index 55b242335420..782d3a7854b4 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -139,6 +139,9 @@ enum mthp_stat_item {
MTHP_STAT_SPLIT_DEFERRED,
MTHP_STAT_NR_ANON,
MTHP_STAT_NR_ANON_PARTIALLY_MAPPED,
+ MTHP_STAT_COLLAPSE_EXCEED_SWAP,
+ MTHP_STAT_COLLAPSE_EXCEED_NONE,
+ MTHP_STAT_COLLAPSE_EXCEED_SHARED,
__MTHP_STAT_COUNT
};

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 7798c9284533..de4704af0022 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -633,6 +633,10 @@ DEFINE_MTHP_STAT_ATTR(split_failed, MTHP_STAT_SPLIT_FAILED);
DEFINE_MTHP_STAT_ATTR(split_deferred, MTHP_STAT_SPLIT_DEFERRED);
DEFINE_MTHP_STAT_ATTR(nr_anon, MTHP_STAT_NR_ANON);
DEFINE_MTHP_STAT_ATTR(nr_anon_partially_mapped, MTHP_STAT_NR_ANON_PARTIALLY_MAPPED);
+DEFINE_MTHP_STAT_ATTR(collapse_exceed_swap_pte, MTHP_STAT_COLLAPSE_EXCEED_SWAP);
+DEFINE_MTHP_STAT_ATTR(collapse_exceed_none_pte, MTHP_STAT_COLLAPSE_EXCEED_NONE);
+DEFINE_MTHP_STAT_ATTR(collapse_exceed_shared_pte, MTHP_STAT_COLLAPSE_EXCEED_SHARED);
+

static struct attribute *anon_stats_attrs[] = {
&anon_fault_alloc_attr.attr,
@@ -649,6 +653,9 @@ static struct attribute *anon_stats_attrs[] = {
&split_deferred_attr.attr,
&nr_anon_attr.attr,
&nr_anon_partially_mapped_attr.attr,
+ &collapse_exceed_swap_pte_attr.attr,
+ &collapse_exceed_none_pte_attr.attr,
+ &collapse_exceed_shared_pte_attr.attr,
NULL,
};

diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 67da0950b833..38643a681ba5 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -604,7 +604,10 @@ static int __collapse_huge_page_isolate(struct vm_area_struct *vma,
continue;
} else {
result = SCAN_EXCEED_NONE_PTE;
- count_vm_event(THP_SCAN_EXCEED_NONE_PTE);
+ if (order == HPAGE_PMD_ORDER)
+ count_vm_event(THP_SCAN_EXCEED_NONE_PTE);
+ else
+ count_mthp_stat(order, MTHP_STAT_COLLAPSE_EXCEED_NONE);
goto out;
}
}
@@ -633,8 +636,14 @@ static int __collapse_huge_page_isolate(struct vm_area_struct *vma,
/* See khugepaged_scan_pmd(). */
if (folio_maybe_mapped_shared(folio)) {
++shared;
- if (order != HPAGE_PMD_ORDER || (cc->is_khugepaged &&
- shared > khugepaged_max_ptes_shared)) {
+ if (order != HPAGE_PMD_ORDER) {
+ result = SCAN_EXCEED_SHARED_PTE;
+ count_mthp_stat(order, MTHP_STAT_COLLAPSE_EXCEED_SHARED);
+ goto out;
+ }
+
+ if (cc->is_khugepaged &&
+ shared > khugepaged_max_ptes_shared) {
result = SCAN_EXCEED_SHARED_PTE;
count_vm_event(THP_SCAN_EXCEED_SHARED_PTE);
goto out;
@@ -1060,6 +1069,7 @@ static int __collapse_huge_page_swapin(struct mm_struct *mm,

/* Dont swapin for mTHP collapse */
if (order != HPAGE_PMD_ORDER) {
+ count_mthp_stat(order, MTHP_STAT_COLLAPSE_EXCEED_SHARED);
result = SCAN_EXCEED_SWAP_PTE;
goto out;
}
--
2.48.1