linux-kernel - Re: [PATCH mm-unstable 8/8] mm/hugetlb: convert demote_free_huge

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Message-ID: <2c593f0b-5a29-2743-9d1d-313cf8bf6d85@oracle.com>
Date:   Mon, 9 Jan 2023 14:53:51 -0600
From:   Sidhartha Kumar <sidhartha.kumar@...cle.com>
To:     John Hubbard <jhubbard@...dia.com>,
        Mike Kravetz <mike.kravetz@...cle.com>
Cc:     Matthew Wilcox <willy@...radead.org>, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, akpm@...ux-foundation.org,
        songmuchun@...edance.com, tsahu@...ux.ibm.com
Subject: Re: [PATCH mm-unstable 8/8] mm/hugetlb: convert demote_free_huge_page
 to folios

On 1/9/23 2:01 PM, John Hubbard wrote:
> On 1/9/23 10:23, Mike Kravetz wrote:
>>>>>> No problems with the code, but I am not in love with the name 
>>>>>> subfolio.
>>>>>> I know it is patterned after 'subpage'.  For better or worse, the 
>>>>>> term
>>>>>> subpage is used throughout the kernel.  This would be the first 
>>>>>> usage of
>>>>>> the term 'subfolio'.
>>>>>>
>>>>>> Matthew do you have any comments on the naming?  It is local to 
>>>>>> hugetlb,
>>>>>> but I would hate to see use of the term subfolio based on its 
>>>>>> introduction
>>>>>> here.
>>>>>
>>>>> I'm really not a fan of it either.  I intended to dive into this patch
>>>>> and understand the function it's modifying, in the hopes of suggesting
>>>>> a better name and/or method.
>>>>
>>>> At a high level, this routine is splitting a very large folio (1G for
>>>> example) into multiple large folios of a smaller size (512 2M folios 
>>>> for
>>>> example).  The loop is iterating through the very large folio at
>>>> increments of the smaller large folio.  subfolio (previously 
>>>> subpage) is
>>>> used to point to the smaller large folio within the loop.
>>>>
>>> If folio does not need to be part of the variable name, how about 
>>> something
>>> like 'demote_target'? The prep call inside the loop would then look 
>>> like:
>>>
>>> prep_new_hugetlb_folio(target_hstate, demote_target, nid);
>>>
>>> so it is still clear that demote_target is a folio. A more concise 
>>> version
>>> could also be 'demote_dst' but that seems more ambiguous than target.
>>
>> I am OK with that naming.  Primary concern was the introduction of the
>> term subfolio.
> 
> How about one of these:
> 
>      smaller_folio
>      inner_folio
> 
> Those are more self-explanatory, while still avoiding "subfolio".
> 
I would be fine with inner_folio.

Thanks,
Sidhartha Kumar

> thanks,