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From: "David Hildenbrand (arm)" <david@kernel.org>
To: Vernon Yang <vernon2gm@gmail.com>
Cc: akpm@linux-foundation.org, lorenzo.stoakes@oracle.com,
	ziy@nvidia.com, dev.jain@arm.com, baohua@kernel.org,
	lance.yang@linux.dev, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org,
	Vernon Yang <yanglincheng@kylinos.cn>
Subject: Re: [PATCH mm-new v6 2/5] mm: khugepaged: refine scan progress number
Date: Thu, 5 Feb 2026 13:11:47 +0100	[thread overview]
Message-ID: <85e8ded9-a9eb-4663-9c96-93af60006fb6@kernel.org> (raw)
In-Reply-To: <CACZaFFNGFWv3FG8spJDLfLTe=0QWuBWL+Lbs+W3h9vGL=jrT6Q@mail.gmail.com>

On 2/5/26 07:08, Vernon Yang wrote:
> On Thu, Feb 5, 2026 at 5:35 AM David Hildenbrand (arm) <david@kernel.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 ... ? :)

-- 
Cheers,

David


  parent reply	other threads:[~2026-02-05 12:11 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-02-01 12:25 [PATCH mm-new v6 0/5] Improve khugepaged scan logic Vernon Yang
2026-02-01 12:25 ` [PATCH mm-new v6 1/5] mm: khugepaged: add trace_mm_khugepaged_scan event Vernon Yang
2026-02-01 12:25 ` [PATCH mm-new v6 2/5] mm: khugepaged: refine scan progress number Vernon Yang
2026-02-04 21:35   ` David Hildenbrand (arm)
2026-02-05  6:08     ` Vernon Yang
2026-02-05 12:07       ` Dev Jain
2026-02-05 12:28         ` David Hildenbrand (Arm)
2026-02-05 12:11       ` David Hildenbrand (arm) [this message]
2026-02-05 14:25         ` Dev Jain
2026-02-05 14:30           ` Dev Jain
2026-02-06  9:03             ` David Hildenbrand (Arm)
2026-02-06  9:02           ` David Hildenbrand (Arm)
2026-02-06 10:00             ` Dev Jain
2026-02-06 11:10               ` David Hildenbrand (Arm)
2026-02-06 11:12             ` Vernon Yang
2026-02-06 13:52               ` Lance Yang
2026-02-08  9:05               ` Dev Jain
2026-02-08  9:32                 ` Lance Yang
2026-02-08 13:23                 ` Vernon Yang
2026-02-01 12:25 ` [PATCH mm-new v6 3/5] mm: add folio_test_lazyfree helper Vernon Yang
2026-02-01 12:25 ` [PATCH mm-new v6 4/5] mm: khugepaged: skip lazy-free folios Vernon Yang
2026-02-03 11:23   ` Lance Yang
2026-02-05  6:01     ` Vernon Yang
2026-02-04 21:23   ` David Hildenbrand (arm)
2026-02-05  6:05     ` Vernon Yang
2026-02-01 12:25 ` [PATCH mm-new v6 5/5] mm: khugepaged: set to next mm direct when mm has MMF_DISABLE_THP_COMPLETELY Vernon Yang

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