linux-kernel - Re: [PATCH v5 6/6] mm: shmem: add mTHP counters for anonymous shmem

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Message-ID: <CAK1f24=Rz4qPyw9pfTHTAuQO6Yv9mFHccjCd75a0kvHvCBH3uA@mail.gmail.com>
Date: Wed, 12 Jun 2024 16:04:08 +0800
From: Lance Yang <ioworker0@...il.com>
To: Baolin Wang <baolin.wang@...ux.alibaba.com>
Cc: akpm@...ux-foundation.org, hughd@...gle.com, willy@...radead.org, 
	david@...hat.com, wangkefeng.wang@...wei.com, ying.huang@...el.com, 
	21cnbao@...il.com, ryan.roberts@....com, shy828301@...il.com, ziy@...dia.com, 
	da.gomez@...sung.com, p.raghav@...sung.com, linux-mm@...ck.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 6/6] mm: shmem: add mTHP counters for anonymous shmem

Hi Baolin,

On Tue, Jun 11, 2024 at 6:11 PM Baolin Wang
<baolin.wang@...ux.alibaba.com> wrote:
>
> Add mTHP counters for anonymous shmem.
>
> Signed-off-by: Baolin Wang <baolin.wang@...ux.alibaba.com>
> ---
>  include/linux/huge_mm.h |  3 +++
>  mm/huge_memory.c        |  6 ++++++
>  mm/shmem.c              | 18 +++++++++++++++---
>  3 files changed, 24 insertions(+), 3 deletions(-)
>
> diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
> index 909cfc67521d..212cca384d7e 100644
> --- a/include/linux/huge_mm.h
> +++ b/include/linux/huge_mm.h
> @@ -281,6 +281,9 @@ enum mthp_stat_item {
>         MTHP_STAT_ANON_FAULT_FALLBACK_CHARGE,
>         MTHP_STAT_SWPOUT,
>         MTHP_STAT_SWPOUT_FALLBACK,
> +       MTHP_STAT_FILE_ALLOC,
> +       MTHP_STAT_FILE_FALLBACK,
> +       MTHP_STAT_FILE_FALLBACK_CHARGE,
>         __MTHP_STAT_COUNT
>  };
>
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index 1360a1903b66..3fbcd77f5957 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -555,6 +555,9 @@ 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(swpout, MTHP_STAT_SWPOUT);
>  DEFINE_MTHP_STAT_ATTR(swpout_fallback, MTHP_STAT_SWPOUT_FALLBACK);
> +DEFINE_MTHP_STAT_ATTR(file_alloc, MTHP_STAT_FILE_ALLOC);
> +DEFINE_MTHP_STAT_ATTR(file_fallback, MTHP_STAT_FILE_FALLBACK);
> +DEFINE_MTHP_STAT_ATTR(file_fallback_charge, MTHP_STAT_FILE_FALLBACK_CHARGE);
>
>  static struct attribute *stats_attrs[] = {
>         &anon_fault_alloc_attr.attr,
> @@ -562,6 +565,9 @@ static struct attribute *stats_attrs[] = {
>         &anon_fault_fallback_charge_attr.attr,
>         &swpout_attr.attr,
>         &swpout_fallback_attr.attr,
> +       &file_alloc_attr.attr,
> +       &file_fallback_attr.attr,
> +       &file_fallback_charge_attr.attr,
>         NULL,
>  };
>
> diff --git a/mm/shmem.c b/mm/shmem.c
> index f5469c357be6..99bd3c34f0fb 100644
> --- a/mm/shmem.c
> +++ b/mm/shmem.c
> @@ -1773,6 +1773,9 @@ static struct folio *shmem_alloc_and_add_folio(struct vm_fault *vmf,
>
>                         if (pages == HPAGE_PMD_NR)
>                                 count_vm_event(THP_FILE_FALLBACK);
> +#ifdef CONFIG_TRANSPARENT_HUGEPAGE
> +                       count_mthp_stat(order, MTHP_STAT_FILE_FALLBACK);
> +#endif

Using the conditional compilation directives here is a bit weird :)
Would there be any issues if we were to drop them?

Since THP_FILE_FALLBACK is working as expected, MTHP_STAT_FILE_FALLBACK
should work as well without the conditional compilation directives, IIUC.

Thanks,
Lance

>                         order = next_order(&suitable_orders, order);
>                 }
>         } else {
> @@ -1792,9 +1795,15 @@ static struct folio *shmem_alloc_and_add_folio(struct vm_fault *vmf,
>                 if (xa_find(&mapping->i_pages, &index,
>                                 index + pages - 1, XA_PRESENT)) {
>                         error = -EEXIST;
> -               } else if (pages == HPAGE_PMD_NR) {
> -                       count_vm_event(THP_FILE_FALLBACK);
> -                       count_vm_event(THP_FILE_FALLBACK_CHARGE);
> +               } else if (pages > 1) {
> +                       if (pages == HPAGE_PMD_NR) {
> +                               count_vm_event(THP_FILE_FALLBACK);
> +                               count_vm_event(THP_FILE_FALLBACK_CHARGE);
> +                       }
> +#ifdef CONFIG_TRANSPARENT_HUGEPAGE
> +                       count_mthp_stat(folio_order(folio), MTHP_STAT_FILE_FALLBACK);
> +                       count_mthp_stat(folio_order(folio), MTHP_STAT_FILE_FALLBACK_CHARGE);
> +#endif
>                 }
>                 goto unlock;
>         }
> @@ -2168,6 +2177,9 @@ static int shmem_get_folio_gfp(struct inode *inode, pgoff_t index,
>                 if (!IS_ERR(folio)) {
>                         if (folio_test_pmd_mappable(folio))
>                                 count_vm_event(THP_FILE_ALLOC);
> +#ifdef CONFIG_TRANSPARENT_HUGEPAGE
> +                       count_mthp_stat(folio_order(folio), MTHP_STAT_FILE_ALLOC);
> +#endif
>                         goto alloced;
>                 }
>                 if (PTR_ERR(folio) == -EEXIST)
> --
> 2.39.3
>