linux-kernel - Re: [PATCH v6 2/4] mm: add per-order mTHP anon_swpout and anon_swpout

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Message-ID: <fba4f0cb-6d18-4d7c-8b2e-3300be1c20e3@redhat.com>
Date: Tue, 16 Apr 2024 10:14:17 +0200
From: David Hildenbrand <david@...hat.com>
To: Barry Song <21cnbao@...il.com>, akpm@...ux-foundation.org,
 linux-mm@...ck.org
Cc: cerasuolodomenico@...il.com, chrisl@...nel.org, kasong@...cent.com,
 linux-kernel@...r.kernel.org, peterx@...hat.com, ryan.roberts@....com,
 surenb@...gle.com, v-songbaohua@...o.com, willy@...radead.org,
 yosryahmed@...gle.com, yuzhao@...gle.com, corbet@....net
Subject: Re: [PATCH v6 2/4] mm: add per-order mTHP anon_swpout and
 anon_swpout_fallback counters

On 12.04.24 13:48, Barry Song wrote:
> From: Barry Song <v-songbaohua@...o.com>
> 
> This helps to display the fragmentation situation of the swapfile, knowing
> the proportion of how much we haven't split large folios.  So far, we only
> support non-split swapout for anon memory, with the possibility of
> expanding to shmem in the future.  So, we add the "anon" prefix to the
> counter names.
> 
> Signed-off-by: Barry Song <v-songbaohua@...o.com>
> Reviewed-by: Ryan Roberts <ryan.roberts@....com>
> Cc: Chris Li <chrisl@...nel.org>
> Cc: David Hildenbrand <david@...hat.com>
> Cc: Domenico Cerasuolo <cerasuolodomenico@...il.com>
> Cc: Kairui Song <kasong@...cent.com>
> Cc: Matthew Wilcox (Oracle) <willy@...radead.org>
> Cc: Peter Xu <peterx@...hat.com>
> Cc: Ryan Roberts <ryan.roberts@....com>
> Cc: Suren Baghdasaryan <surenb@...gle.com>
> Cc: Yosry Ahmed <yosryahmed@...gle.com>
> Cc: Yu Zhao <yuzhao@...gle.com>
> ---
>   include/linux/huge_mm.h | 2 ++
>   mm/huge_memory.c        | 4 ++++
>   mm/page_io.c            | 1 +
>   mm/vmscan.c             | 3 +++
>   4 files changed, 10 insertions(+)
> 
> diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
> index d4fdb2641070..7cd07b83a3d0 100644
> --- a/include/linux/huge_mm.h
> +++ b/include/linux/huge_mm.h
> @@ -268,6 +268,8 @@ enum mthp_stat_item {
>   	MTHP_STAT_ANON_FAULT_ALLOC,
>   	MTHP_STAT_ANON_FAULT_FALLBACK,
>   	MTHP_STAT_ANON_FAULT_FALLBACK_CHARGE,
> +	MTHP_STAT_ANON_SWPOUT,
> +	MTHP_STAT_ANON_SWPOUT_FALLBACK,
>   	__MTHP_STAT_COUNT
>   };
>   
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index dfc38cc83a04..58f2c4745d80 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -555,11 +555,15 @@ static struct kobj_attribute _name##_attr = __ATTR_RO(_name)
>   DEFINE_MTHP_STAT_ATTR(anon_fault_alloc, MTHP_STAT_ANON_FAULT_ALLOC);
>   DEFINE_MTHP_STAT_ATTR(anon_fault_fallback, MTHP_STAT_ANON_FAULT_FALLBACK);
>   DEFINE_MTHP_STAT_ATTR(anon_fault_fallback_charge, MTHP_STAT_ANON_FAULT_FALLBACK_CHARGE);
> +DEFINE_MTHP_STAT_ATTR(anon_swpout, MTHP_STAT_ANON_SWPOUT);
> +DEFINE_MTHP_STAT_ATTR(anon_swpout_fallback, MTHP_STAT_ANON_SWPOUT_FALLBACK);
>   
>   static struct attribute *stats_attrs[] = {
>   	&anon_fault_alloc_attr.attr,
>   	&anon_fault_fallback_attr.attr,
>   	&anon_fault_fallback_charge_attr.attr,
> +	&anon_swpout_attr.attr,
> +	&anon_swpout_fallback_attr.attr,
>   	NULL,
>   };
>   
> diff --git a/mm/page_io.c b/mm/page_io.c
> index a9a7c236aecc..46c603dddf04 100644
> --- a/mm/page_io.c
> +++ b/mm/page_io.c
> @@ -217,6 +217,7 @@ static inline void count_swpout_vm_event(struct folio *folio)
>   		count_memcg_folio_events(folio, THP_SWPOUT, 1);
>   		count_vm_event(THP_SWPOUT);
>   	}
> +	count_mthp_stat(folio_order(folio), MTHP_STAT_ANON_SWPOUT);
>   #endif
>   	count_vm_events(PSWPOUT, folio_nr_pages(folio));
>   }
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index bca2d9981c95..49bd94423961 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -1231,6 +1231,8 @@ static unsigned int shrink_folio_list(struct list_head *folio_list,
>   						goto activate_locked;
>   				}
>   				if (!add_to_swap(folio)) {
> +					int __maybe_unused order = folio_order(folio);
> +
>   					if (!folio_test_large(folio))
>   						goto activate_locked_split;
>   					/* Fallback to swap normal pages */
> @@ -1242,6 +1244,7 @@ static unsigned int shrink_folio_list(struct list_head *folio_list,
>   							THP_SWPOUT_FALLBACK, 1);
>   						count_vm_event(THP_SWPOUT_FALLBACK);
>   					}
> +					count_mthp_stat(order, MTHP_STAT_ANON_SWPOUT_FALLBACK);

Why the temporary variable for order?

count_mthp_stat(folio_order(order),
                 MTHP_STAT_ANON_SWPOUT_FALLBACK);

.. but now I do wonder if we want to pass the folio to count_mthp_stat() ?

Anyhow

Acked-by: David Hildenbrand <david@...hat.com>

-- 
Cheers,

David / dhildenb