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

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Message-ID: <acb25f5d-b099-42a8-be26-c60b79502e3a@arm.com>
Date: Thu, 5 Feb 2026 20:00:15 +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 7:55 pm, Dev Jain wrote:
> 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.

I realize I shouldn't have bolded out the "literally" - below I wrote that
I won't shout, but the bold seems like shouting :)

>
>
>
> Anyhow, I won't shout in any case : ) If you deem incrementing in the
>
> loop prettier, that's fine.
>
>