linux-kernel - Re: [PATCH 0/2] mm: introduce per-order mTHP split counters

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Message-ID: <CAK1f24nHs5CjEn4DHm46e6g=RUGQReztRZRUzHtYuqCmvACqaQ@mail.gmail.com>
Date: Wed, 24 Apr 2024 23:53:45 +0800
From: Lance Yang <ioworker0@...il.com>
To: David Hildenbrand <david@...hat.com>
Cc: Ryan Roberts <ryan.roberts@....com>, akpm@...ux-foundation.org, 21cnbao@...il.com, 
	baolin.wang@...ux.alibaba.com, linux-kernel@...r.kernel.org, 
	linux-mm@...ck.org
Subject: Re: [PATCH 0/2] mm: introduce per-order mTHP split counters

On Wed, Apr 24, 2024 at 11:29 PM David Hildenbrand <david@...hat.com> wrote:
>
> On 24.04.24 17:20, Ryan Roberts wrote:
> > On 24/04/2024 16:00, David Hildenbrand wrote:
> >> On 24.04.24 15:51, Lance Yang wrote:
> >>> Hi all,
> >>>
> >>> At present, the split counters in THP statistics no longer include
> >>> PTE-mapped mTHP. Therefore, we want to introduce per-order mTHP split
> >>> counters to monitor the frequency of mTHP splits. This will assist
> >>> developers in better analyzing and optimizing system performance.
> >>>
> >>> /sys/kernel/mm/transparent_hugepage/hugepages-<size>/stats
> >>>           split_page
> >>>           split_page_failed
> >>>           deferred_split_page
> >>>
> >>> Thanks,
> >>> Lance
> >>> ---
> >>>
> >>> Lance Yang (2):
> >>>    mm: add per-order mTHP split counters
> >>>    mm: add docs for per-order mTHP split counters
> >>>
> >>>    Documentation/admin-guide/mm/transhuge.rst | 16 ----------------
> >>
> >> We really have to start documenting these, and what the sementics are.
> >
> > I think the diffstat is backwards; the series definitely adds more lines than it
> > removes. And patch 2 is adding 16 lines of docs, not removing them. How are you
> > generating this? `git format-patch` should do it correctly for you.
> >
> >>
> >> E.g., is split_page_failed contained in split_page? Is deferred_split_page
> >> contained in split_page?
> >>
> >> But also: just don't call it "split_page". Drop the "_page".
> >>
> >> split
> >> split_failed
> >> split_deferred
> >
> > I guess we are back in "should we be consistent with the existing vmstats"
> > territory, which uses split_page/split_page_failed/deferred_split_page
> >
>
> Yeah, "thp_split_page" really is odd "transparent huge page split page".
>
> > But here, I agree that dropping _page is nicer.
> Right; we also shouldn't call it "thp_split_page" here :)

Yep, I understood. Let's drop the "_page".

split
split_failed
split_deferred

Thanks,
Lance

>
> --
> Cheers,
>
> David / dhildenb
>