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

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Message-ID: <CAGsJ_4wemLBdoV4TMaeSWThMtVJtU+HjyAVwKDV978mAOqkhBA@mail.gmail.com>
Date: Thu, 31 Oct 2024 14:13:04 +1300
From: Barry Song <21cnbao@...il.com>
To: "Huang, Ying" <ying.huang@...el.com>
Cc: akpm@...ux-foundation.org, linux-mm@...ck.org, 
	linux-kernel@...r.kernel.org, Barry Song <v-songbaohua@...o.com>, 
	Baolin Wang <baolin.wang@...ux.alibaba.com>, David Hildenbrand <david@...hat.com>, 
	Chris Li <chrisl@...nel.org>, Yosry Ahmed <yosryahmed@...gle.com>, 
	Kairui Song <kasong@...cent.com>, Ryan Roberts <ryan.roberts@....com>, 
	Kanchana P Sridhar <kanchana.p.sridhar@...el.com>, Usama Arif <usamaarif642@...il.com>
Subject: Re: [PATCH v2] mm: add per-order mTHP swpin counters

On Thu, Oct 31, 2024 at 1:39 PM Huang, Ying <ying.huang@...el.com> wrote:
>
> Barry Song <21cnbao@...il.com> writes:
>
> > From: Barry Song <v-songbaohua@...o.com>
> >
> > This helps profile the sizes of folios being swapped in. Currently,
> > only mTHP swap-out is being counted.
> > The new interface can be found at:
> > /sys/kernel/mm/transparent_hugepage/hugepages-<size>/stats
> >          swpin
>
> This looks strange, why isn't it
>
> /sys/kernel/mm/transparent_hugepage/hugepages-<size>/stats/swpin
>
> ?

I might be mistaken, but I want to highlight the path and new interface
separately, as I’ve done in ec33687c67493 ("mm: add per-order mTHP
anon_fault_alloc and anon_fault_fallback counters"):

If you prefer it on the same line, I’m completely fine with sending v3
to make the change.

>
> > For example,
> > cat /sys/kernel/mm/transparent_hugepage/hugepages-64kB/stats/swpin
> > 12809
> > cat /sys/kernel/mm/transparent_hugepage/hugepages-32kB/stats/swpin
> > 4763
>
> You miss "$"?

Yes.

>
> $ cat /sys/kernel/mm/transparent_hugepage/hugepages-64kB/stats/swpin
> 12809
> $ cat /sys/kernel/mm/transparent_hugepage/hugepages-32kB/stats/swpin
> 4763
>
> > Signed-off-by: Barry Song <v-songbaohua@...o.com>
> > Reviewed-by: Baolin Wang <baolin.wang@...ux.alibaba.com>
> > Acked-by: David Hildenbrand <david@...hat.com>
> > Cc: Chris Li <chrisl@...nel.org>
> > Cc: Yosry Ahmed <yosryahmed@...gle.com>
> > Cc: "Huang, Ying" <ying.huang@...el.com>
> > Cc: Kairui Song <kasong@...cent.com>
> > Cc: Ryan Roberts <ryan.roberts@....com>
> > Cc: Kanchana P Sridhar <kanchana.p.sridhar@...el.com>
> > Cc: Usama Arif <usamaarif642@...il.com>
> > ---
> >  -v2:
> >  * collect Baolin's reviewed-by and David's acked-by, thanks!
> >  * add some examples for the interface in the changelog, Per
> >    Huang, Ying. thanks!
> >  * add a blank line in doc which was missed in v1.
> >
> >  Documentation/admin-guide/mm/transhuge.rst | 4 ++++
> >  include/linux/huge_mm.h                    | 1 +
> >  mm/huge_memory.c                           | 3 +++
> >  mm/page_io.c                               | 3 +++
> >  4 files changed, 11 insertions(+)
> >
> > diff --git a/Documentation/admin-guide/mm/transhuge.rst b/Documentation/admin-guide/mm/transhuge.rst
> > index 2a171ed5206e..5caa3fb2feb1 100644
> > --- a/Documentation/admin-guide/mm/transhuge.rst
> > +++ b/Documentation/admin-guide/mm/transhuge.rst
> > @@ -534,6 +534,10 @@ zswpout
> >       is incremented every time a huge page is swapped out to zswap in one
> >       piece without splitting.
> >
> > +swpin
> > +     is incremented every time a huge page is swapped in from a non-zswap
> > +     swap device in one piece.
> > +
> >  swpout
> >       is incremented every time a huge page is swapped out to a non-zswap
> >       swap device in one piece without splitting.
> > diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
> > index c59e5aa9b081..b94c2e8ee918 100644
> > --- a/include/linux/huge_mm.h
> > +++ b/include/linux/huge_mm.h
> > @@ -120,6 +120,7 @@ enum mthp_stat_item {
> >       MTHP_STAT_ANON_FAULT_FALLBACK,
> >       MTHP_STAT_ANON_FAULT_FALLBACK_CHARGE,
> >       MTHP_STAT_ZSWPOUT,
> > +     MTHP_STAT_SWPIN,
> >       MTHP_STAT_SWPOUT,
> >       MTHP_STAT_SWPOUT_FALLBACK,
> >       MTHP_STAT_SHMEM_ALLOC,
> > diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> > index b26c6503e993..f92068864469 100644
> > --- a/mm/huge_memory.c
> > +++ b/mm/huge_memory.c
> > @@ -616,6 +616,7 @@ 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(zswpout, MTHP_STAT_ZSWPOUT);
> > +DEFINE_MTHP_STAT_ATTR(swpin, MTHP_STAT_SWPIN);
> >  DEFINE_MTHP_STAT_ATTR(swpout, MTHP_STAT_SWPOUT);
> >  DEFINE_MTHP_STAT_ATTR(swpout_fallback, MTHP_STAT_SWPOUT_FALLBACK);
> >  #ifdef CONFIG_SHMEM
> > @@ -635,6 +636,7 @@ static struct attribute *anon_stats_attrs[] = {
> >       &anon_fault_fallback_charge_attr.attr,
> >  #ifndef CONFIG_SHMEM
> >       &zswpout_attr.attr,
> > +     &swpin_attr.attr,
> >       &swpout_attr.attr,
> >       &swpout_fallback_attr.attr,
> >  #endif
> > @@ -666,6 +668,7 @@ static struct attribute_group file_stats_attr_grp = {
> >  static struct attribute *any_stats_attrs[] = {
> >  #ifdef CONFIG_SHMEM
> >       &zswpout_attr.attr,
> > +     &swpin_attr.attr,
> >       &swpout_attr.attr,
> >       &swpout_fallback_attr.attr,
> >  #endif
> > diff --git a/mm/page_io.c b/mm/page_io.c
> > index c69fab5060a1..5d9b6e6cf96c 100644
> > --- a/mm/page_io.c
> > +++ b/mm/page_io.c
> > @@ -487,6 +487,7 @@ static void sio_read_complete(struct kiocb *iocb, long ret)
> >               for (p = 0; p < sio->pages; p++) {
> >                       struct folio *folio = page_folio(sio->bvec[p].bv_page);
> >
> > +                     count_mthp_stat(folio_order(folio), MTHP_STAT_SWPIN);
> >                       count_memcg_folio_events(folio, PSWPIN, folio_nr_pages(folio));
> >                       folio_mark_uptodate(folio);
> >                       folio_unlock(folio);
> > @@ -573,6 +574,7 @@ static void swap_read_folio_bdev_sync(struct folio *folio,
> >        * attempt to access it in the page fault retry time check.
> >        */
> >       get_task_struct(current);
> > +     count_mthp_stat(folio_order(folio), MTHP_STAT_SWPIN);
> >       count_memcg_folio_events(folio, PSWPIN, folio_nr_pages(folio));
> >       count_vm_events(PSWPIN, folio_nr_pages(folio));
> >       submit_bio_wait(&bio);
> > @@ -589,6 +591,7 @@ static void swap_read_folio_bdev_async(struct folio *folio,
> >       bio->bi_iter.bi_sector = swap_folio_sector(folio);
> >       bio->bi_end_io = end_swap_bio_read;
> >       bio_add_folio_nofail(bio, folio, folio_size(folio), 0);
> > +     count_mthp_stat(folio_order(folio), MTHP_STAT_SWPIN);
> >       count_memcg_folio_events(folio, PSWPIN, folio_nr_pages(folio));
> >       count_vm_events(PSWPIN, folio_nr_pages(folio));
> >       submit_bio(bio);
>
> --
> Best Regards,
> Huang, Ying