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

Nico Pache
2025-04-28T15:45:45Z

On Thu, Apr 24, 2025 at 1:58 AM Baolin Wang
<baolin.wang@linux.alibaba.com> wrote:
>
>
>
> On 2025/4/17 08:02, Nico Pache wrote:
> > 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);
>
> Should be MTHP_STAT_COLLAPSE_EXCEED_SWAP?
Yes! Thank you, I will fix this :)
>
> > result = SCAN_EXCEED_SWAP_PTE;
> > goto out;
> > }
>