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

[Huang, Ying]

Barry Song <21cnbao@xxxxxxxxx> writes:

> On Thu, Oct 31, 2024 at 1:39 PM Huang, Ying <ying.huang@xxxxxxxxx> wrote:
>>
>> Barry Song <21cnbao@xxxxxxxxx> writes:
>>
>> > From: Barry Song <v-songbaohua@xxxxxxxx>
>> >
>> > 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.

I am fine to highlight the new interface.  May be something like

In /sys/kernel/mm/transparent_hugepage/hugepages-<size>/stats, 'swpin'
is added for ...

However, I have no strong opinion here.  If everyone except me feels
confusing, that should be fine.

>>
>> > 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@xxxxxxxx>
>> > Reviewed-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
>> > Acked-by: David Hildenbrand <david@xxxxxxxxxx>
>> > Cc: Chris Li <chrisl@xxxxxxxxxx>
>> > Cc: Yosry Ahmed <yosryahmed@xxxxxxxxxx>
>> > Cc: "Huang, Ying" <ying.huang@xxxxxxxxx>
>> > Cc: Kairui Song <kasong@xxxxxxxxxxx>
>> > Cc: Ryan Roberts <ryan.roberts@xxxxxxx>
>> > Cc: Kanchana P Sridhar <kanchana.p.sridhar@xxxxxxxxx>
>> > Cc: Usama Arif <usamaarif642@xxxxxxxxx>
>> > ---
>> >  -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