linux-kernel - Re: [PATCH v2 0/8] Introduce a huge-page pre-zeroing mechanism

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Message-ID: <54a7e6ff-b3bc-4de4-af26-03fa1400d5f9@kernel.org>
Date: Wed, 21 Jan 2026 13:32:29 +0100
From: "David Hildenbrand (Red Hat)" <david@...nel.org>
To: David Laight <david.laight.linux@...il.com>,
 Li Zhe <lizhe.67@...edance.com>
Cc: akpm@...ux-foundation.org, dan.j.williams@...el.com, dave@...olabs.net,
 ankur.a.arora@...cle.com, fvdl@...gle.com, gourry@...rry.net,
 joao.m.martins@...cle.com, jonathan.cameron@...wei.com,
 linux-cxl@...r.kernel.org, linux-kernel@...r.kernel.org, linux-mm@...ck.org,
 mhocko@...e.com, mjguzik@...il.com, muchun.song@...ux.dev,
 osalvador@...e.de, raghavendra.kt@....com, wangzhou1@...ilicon.com,
 zhanjie9@...ilicon.com
Subject: Re: [PATCH v2 0/8] Introduce a huge-page pre-zeroing mechanism

On 1/20/26 10:47, David Laight wrote:
> On Tue, 20 Jan 2026 14:27:06 +0800
> "Li Zhe" <lizhe.67@...edance.com> wrote:
> 
>> In light of the preceding discussion, we appear to have reached the
>> following understanding:
>>
>> (1) At present we prefer to mitigate slow application startup (e.g.,
>> VM creation) by zeroing huge pages at the moment they are freed
>> (init_on_free). The principal benefit is that user space gains the
>> performance improvement without deploying any additional user space
>> daemon.
> 
> Am I missing something?
> If userspace does:
> $ program_a; program_b
> and pages used by program_a are zeroed when it exits you get the delay
> for zeroing all the pages it used before program_b starts.
> OTOH if the zeroing is deferred program_b only needs to zero the pages
> it needs to start (and there may be some lurking).

Can you point me to where was that spelled out as a requirement?

> 
> The only real gain has to come from zeroing pages when the system is idle.
> That will give plenty of zeroed pages needed for starting a web browser
> from the desktop and also speed up single-threaded things like 'make -j1'.

I am strictly against over-engineering any features that hugetlb 
benefits from only.

-- 
Cheers

David