Re: [PATCH mm-new v4 1/6] mm: khugepaged: add trace_mm_khugepaged_scan event

[Vernon Yang]

On Sun, Jan 11, 2026 at 9:49 PM Lance Yang <lance.yang@xxxxxxxxx> wrote:
>
> On 2026/1/11 20:19, Vernon Yang wrote:
> > Add mm_khugepaged_scan event to track the total time for full scan
> > and the total number of pages scanned of khugepaged.
> >
> > Signed-off-by: Vernon Yang <yanglincheng@xxxxxxxxxx>
> > Acked-by: David Hildenbrand (Red Hat) <david@xxxxxxxxxx>
> > Reviewed-by: Barry Song <baohua@xxxxxxxxxx>
> > ---
> >   include/trace/events/huge_memory.h | 24 ++++++++++++++++++++++++
> >   mm/khugepaged.c                    |  2 ++
> >   2 files changed, 26 insertions(+)
> >
> > diff --git a/include/trace/events/huge_memory.h b/include/trace/events/huge_memory.h
> > index 4e41bff31888..3d1069c3f0c5 100644
> > --- a/include/trace/events/huge_memory.h
> > +++ b/include/trace/events/huge_memory.h
> > @@ -237,5 +237,29 @@ TRACE_EVENT(mm_khugepaged_collapse_file,
> >               __print_symbolic(__entry->result, SCAN_STATUS))
> >   );
> >
> > +TRACE_EVENT(mm_khugepaged_scan,
> > +
> > +     TP_PROTO(struct mm_struct *mm, int progress, bool full_scan_finished),
> > +
> > +     TP_ARGS(mm, progress, full_scan_finished),
> > +
> > +     TP_STRUCT__entry(
> > +             __field(struct mm_struct *, mm)
> > +             __field(int, progress)
>
> Nit: progress should be unsigned int here, not int :)

Thank you for the review, I will fix it in the next version.

> Otherwise, LGTM.
>
> Reviewed-by: Lance Yang <lance.yang@xxxxxxxxx>
>
> > +             __field(bool, full_scan_finished)
> > +     ),
> > +
> > +     TP_fast_assign(
> > +             __entry->mm = mm;
> > +             __entry->progress = progress;
> > +             __entry->full_scan_finished = full_scan_finished;
> > +     ),
> > +
> > +     TP_printk("mm=%p, progress=%d, full_scan_finished=%d",
> > +             __entry->mm,
> > +             __entry->progress,
> > +             __entry->full_scan_finished)
> > +);
> > +
> >   #endif /* __HUGE_MEMORY_H */
> >   #include <trace/define_trace.h>
> > diff --git a/mm/khugepaged.c b/mm/khugepaged.c
> > index 9f790ec34400..2e570f83778c 100644
> > --- a/mm/khugepaged.c
> > +++ b/mm/khugepaged.c
> > @@ -2545,6 +2545,8 @@ static unsigned int khugepaged_scan_mm_slot(unsigned int pages, enum scan_result
> >               collect_mm_slot(slot);
> >       }
> >
> > +     trace_mm_khugepaged_scan(mm, progress, khugepaged_scan.mm_slot == NULL);
> > +
> >       return progress;
> >   }
> >
>