linux-kernel - Re: [PATCH v2 5/5] mm: add per-order mTHP swpin

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Date: Wed, 17 Apr 2024 08:45:07 +0800
From: "Huang, Ying" <ying.huang@...el.com>
To: Barry Song <21cnbao@...il.com>
Cc: akpm@...ux-foundation.org,  linux-mm@...ck.org,
  baolin.wang@...ux.alibaba.com,  chrisl@...nel.org,  david@...hat.com,
  hanchuanhua@...o.com,  hannes@...xchg.org,  hughd@...gle.com,
  kasong@...cent.com,  ryan.roberts@....com,  surenb@...gle.com,
  v-songbaohua@...o.com,  willy@...radead.org,  xiang@...nel.org,
  yosryahmed@...gle.com,  yuzhao@...gle.com,  ziy@...dia.com,
  linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 5/5] mm: add per-order mTHP swpin_refault counter

Barry Song <21cnbao@...il.com> writes:

> From: Barry Song <v-songbaohua@...o.com>
>
> Currently, we are handling the scenario where we've hit a
> large folio in the swapcache, and the reclaiming process
> for this large folio is still ongoing.
>
> Signed-off-by: Barry Song <v-songbaohua@...o.com>
> ---
>  include/linux/huge_mm.h | 1 +
>  mm/huge_memory.c        | 2 ++
>  mm/memory.c             | 1 +
>  3 files changed, 4 insertions(+)
>
> diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
> index c8256af83e33..b67294d5814f 100644
> --- a/include/linux/huge_mm.h
> +++ b/include/linux/huge_mm.h
> @@ -269,6 +269,7 @@ enum mthp_stat_item {
>  	MTHP_STAT_ANON_ALLOC_FALLBACK,
>  	MTHP_STAT_ANON_SWPOUT,
>  	MTHP_STAT_ANON_SWPOUT_FALLBACK,
> +	MTHP_STAT_ANON_SWPIN_REFAULT,

This is different from the refault concept used in other place in mm
subystem.  Please check the following code

	if (shadow)
		workingset_refault(folio, shadow);

in __read_swap_cache_async().

>  	__MTHP_STAT_COUNT
>  };

--
Best Regards,
Huang, Ying

> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index d8d2ed80b0bf..fb95345b0bde 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -556,12 +556,14 @@ DEFINE_MTHP_STAT_ATTR(anon_alloc, MTHP_STAT_ANON_ALLOC);
>  DEFINE_MTHP_STAT_ATTR(anon_alloc_fallback, MTHP_STAT_ANON_ALLOC_FALLBACK);
>  DEFINE_MTHP_STAT_ATTR(anon_swpout, MTHP_STAT_ANON_SWPOUT);
>  DEFINE_MTHP_STAT_ATTR(anon_swpout_fallback, MTHP_STAT_ANON_SWPOUT_FALLBACK);
> +DEFINE_MTHP_STAT_ATTR(anon_swpin_refault, MTHP_STAT_ANON_SWPIN_REFAULT);
>  
>  static struct attribute *stats_attrs[] = {
>  	&anon_alloc_attr.attr,
>  	&anon_alloc_fallback_attr.attr,
>  	&anon_swpout_attr.attr,
>  	&anon_swpout_fallback_attr.attr,
> +	&anon_swpin_refault_attr.attr,
>  	NULL,
>  };
>  
> diff --git a/mm/memory.c b/mm/memory.c
> index 9818dc1893c8..acc023795a4d 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -4167,6 +4167,7 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
>  		nr_pages = nr;
>  		entry = folio->swap;
>  		page = &folio->page;
> +		count_mthp_stat(folio_order(folio), MTHP_STAT_ANON_SWPIN_REFAULT);
>  	}
>  
>  check_pte: