Re: [PATCH v10 11/13] khugepaged: improve tracepoints for mTHP orders

[Lorenzo Stoakes <lorenzo.stoakes@oracle.com>]

On Tue, Aug 19, 2025 at 07:42:03AM -0600, Nico Pache wrote:
> Add the order to the tracepoints to give better insight into what order
> is being operated at for khugepaged.

NIT: Would be good to list the tracepoints you changed here.

>
> Acked-by: David Hildenbrand <david@redhat.com>
> Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
> Signed-off-by: Nico Pache <npache@redhat.com>

LGTM to me, so:

Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>

> ---
>  include/trace/events/huge_memory.h | 34 +++++++++++++++++++-----------
>  mm/khugepaged.c                    | 10 +++++----
>  2 files changed, 28 insertions(+), 16 deletions(-)
>
> diff --git a/include/trace/events/huge_memory.h b/include/trace/events/huge_memory.h
> index 2305df6cb485..56aa8c3b011b 100644
> --- a/include/trace/events/huge_memory.h
> +++ b/include/trace/events/huge_memory.h
> @@ -92,34 +92,37 @@ TRACE_EVENT(mm_khugepaged_scan_pmd,
>
>  TRACE_EVENT(mm_collapse_huge_page,
>
> -	TP_PROTO(struct mm_struct *mm, int isolated, int status),
> +	TP_PROTO(struct mm_struct *mm, int isolated, int status, unsigned int order),
>
> -	TP_ARGS(mm, isolated, status),
> +	TP_ARGS(mm, isolated, status, order),
>
>  	TP_STRUCT__entry(
>  		__field(struct mm_struct *, mm)
>  		__field(int, isolated)
>  		__field(int, status)
> +		__field(unsigned int, order)
>  	),
>
>  	TP_fast_assign(
>  		__entry->mm = mm;
>  		__entry->isolated = isolated;
>  		__entry->status = status;
> +		__entry->order = order;
>  	),
>
> -	TP_printk("mm=%p, isolated=%d, status=%s",
> +	TP_printk("mm=%p, isolated=%d, status=%s order=%u",
>  		__entry->mm,
>  		__entry->isolated,
> -		__print_symbolic(__entry->status, SCAN_STATUS))
> +		__print_symbolic(__entry->status, SCAN_STATUS),
> +		__entry->order)
>  );
>
>  TRACE_EVENT(mm_collapse_huge_page_isolate,
>
>  	TP_PROTO(struct folio *folio, int none_or_zero,
> -		 int referenced, bool  writable, int status),
> +		 int referenced, bool  writable, int status, unsigned int order),
>
> -	TP_ARGS(folio, none_or_zero, referenced, writable, status),
> +	TP_ARGS(folio, none_or_zero, referenced, writable, status, order),
>
>  	TP_STRUCT__entry(
>  		__field(unsigned long, pfn)
> @@ -127,6 +130,7 @@ TRACE_EVENT(mm_collapse_huge_page_isolate,
>  		__field(int, referenced)
>  		__field(bool, writable)
>  		__field(int, status)
> +		__field(unsigned int, order)
>  	),
>
>  	TP_fast_assign(
> @@ -135,27 +139,31 @@ TRACE_EVENT(mm_collapse_huge_page_isolate,
>  		__entry->referenced = referenced;
>  		__entry->writable = writable;
>  		__entry->status = status;
> +		__entry->order = order;
>  	),
>
> -	TP_printk("scan_pfn=0x%lx, none_or_zero=%d, referenced=%d, writable=%d, status=%s",
> +	TP_printk("scan_pfn=0x%lx, none_or_zero=%d, referenced=%d, writable=%d, status=%s order=%u",
>  		__entry->pfn,
>  		__entry->none_or_zero,
>  		__entry->referenced,
>  		__entry->writable,
> -		__print_symbolic(__entry->status, SCAN_STATUS))
> +		__print_symbolic(__entry->status, SCAN_STATUS),
> +		__entry->order)
>  );
>
>  TRACE_EVENT(mm_collapse_huge_page_swapin,
>
> -	TP_PROTO(struct mm_struct *mm, int swapped_in, int referenced, int ret),
> +	TP_PROTO(struct mm_struct *mm, int swapped_in, int referenced, int ret,
> +		 unsigned int order),
>
> -	TP_ARGS(mm, swapped_in, referenced, ret),
> +	TP_ARGS(mm, swapped_in, referenced, ret, order),
>
>  	TP_STRUCT__entry(
>  		__field(struct mm_struct *, mm)
>  		__field(int, swapped_in)
>  		__field(int, referenced)
>  		__field(int, ret)
> +		__field(unsigned int, order)
>  	),
>
>  	TP_fast_assign(
> @@ -163,13 +171,15 @@ TRACE_EVENT(mm_collapse_huge_page_swapin,
>  		__entry->swapped_in = swapped_in;
>  		__entry->referenced = referenced;
>  		__entry->ret = ret;
> +		__entry->order = order;
>  	),
>
> -	TP_printk("mm=%p, swapped_in=%d, referenced=%d, ret=%d",
> +	TP_printk("mm=%p, swapped_in=%d, referenced=%d, ret=%d, order=%u",
>  		__entry->mm,
>  		__entry->swapped_in,
>  		__entry->referenced,
> -		__entry->ret)
> +		__entry->ret,
> +		__entry->order)
>  );
>
>  TRACE_EVENT(mm_khugepaged_scan_file,
> diff --git a/mm/khugepaged.c b/mm/khugepaged.c
> index 81d2ffd56ab9..c13bc583a368 100644
> --- a/mm/khugepaged.c
> +++ b/mm/khugepaged.c
> @@ -721,13 +721,14 @@ static int __collapse_huge_page_isolate(struct vm_area_struct *vma,
>  	} else {
>  		result = SCAN_SUCCEED;
>  		trace_mm_collapse_huge_page_isolate(folio, none_or_zero,
> -						    referenced, writable, result);
> +						    referenced, writable, result,
> +						    order);
>  		return result;
>  	}
>  out:
>  	release_pte_pages(pte, _pte, compound_pagelist);
>  	trace_mm_collapse_huge_page_isolate(folio, none_or_zero,
> -					    referenced, writable, result);
> +					    referenced, writable, result, order);
>  	return result;
>  }
>
> @@ -1123,7 +1124,8 @@ static int __collapse_huge_page_swapin(struct mm_struct *mm,
>
>  	result = SCAN_SUCCEED;
>  out:
> -	trace_mm_collapse_huge_page_swapin(mm, swapped_in, referenced, result);
> +	trace_mm_collapse_huge_page_swapin(mm, swapped_in, referenced, result,
> +					   order);
>  	return result;
>  }
>
> @@ -1348,7 +1350,7 @@ static int collapse_huge_page(struct mm_struct *mm, unsigned long address,
>  	*mmap_locked = false;
>  	if (folio)
>  		folio_put(folio);
> -	trace_mm_collapse_huge_page(mm, result == SCAN_SUCCEED, result);
> +	trace_mm_collapse_huge_page(mm, result == SCAN_SUCCEED, result, order);
>  	return result;
>  }
>
> --
> 2.50.1
>