linux-kernel - Re: [PATCH mm-new v6 2/5] mm: khugepaged: refine scan progress number

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Message-ID: <9508744b-e5d5-49ef-825f-eef683892541@arm.com>
Date: Thu, 5 Feb 2026 19:55:28 +0530
From: Dev Jain <dev.jain@....com>
To: "David Hildenbrand (arm)" <david@...nel.org>,
 Vernon Yang <vernon2gm@...il.com>
Cc: akpm@...ux-foundation.org, lorenzo.stoakes@...cle.com, ziy@...dia.com,
 baohua@...nel.org, lance.yang@...ux.dev, linux-mm@...ck.org,
 linux-kernel@...r.kernel.org, Vernon Yang <yanglincheng@...inos.cn>
Subject: Re: [PATCH mm-new v6 2/5] mm: khugepaged: refine scan progress number


On 05/02/26 5:41 pm, David Hildenbrand (arm) wrote:
> On 2/5/26 07:08, Vernon Yang wrote:
>> On Thu, Feb 5, 2026 at 5:35 AM David Hildenbrand (arm)
>> <david@...nel.org> wrote:
>>>
>>> [...]
>>>
>>>> +     if (cur_progress) {
>>>> +             if (_pte >= pte + HPAGE_PMD_NR)
>>>> +                     *cur_progress = HPAGE_PMD_NR;
>>>> +             else
>>>> +                     *cur_progress = _pte - pte + 1;
>>>
>>> *cur_progress = max(_pte - pte + 1, HPAGE_PMD_NR);
>>
>> I guess, your meaning is "min(_pte - pte + 1, HPAGE_PMD_NR)", not max().
>
> Yes!
>
>>
>>> ?
>>>
>>> It's still a bit nasty, though.
>>>
>>> Can't we just add one at the beginning of the loop and let the compiler
>>> optimize that? ;)
>>
>> I'm also worried that the compiler can't optimize this since the body of
>> the loop is complex, as with Dev's opinion [1].
>
> Why do we even have to optimize this? :)
>
> Premature ... ? :)


I mean .... we don't, but the alternate is a one liner using max().

The objective is to compute the number of iterations of the for-loop.

It just seems weird to me to track that in the loop, when we have the

loop iterator, which *literally* does that only.



Anyhow, I won't shout in any case : ) If you deem incrementing in the

loop prettier, that's fine.