Re: [PATCH v2 5/5] mm: add per-order mTHP swpin_refault counter

From: Huang, Ying
Date: Tue Apr 16 2024 - 20:47:15 EST


Barry Song <21cnbao@xxxxxxxxx> writes:

> From: Barry Song <v-songbaohua@xxxxxxxx>
>
> 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@xxxxxxxx>
> ---
> 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: