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

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Message-ID: <11455268-d522-4b3a-8961-892e42cc50f0@arm.com>
Date: Wed, 24 Apr 2024 16:20:15 +0100
From: Ryan Roberts <ryan.roberts@....com>
To: David Hildenbrand <david@...hat.com>, Lance Yang <ioworker0@...il.com>,
 akpm@...ux-foundation.org
Cc: 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 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

But here, I agree that dropping _page is nicer.

> 
> ?
>