linux-kernel - Re: [PATCH v11 00/15] khugepaged: mTHP support

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Message-ID: <aa15dcd0-15d3-45ad-b24f-737539bff861@redhat.com>
Date: Fri, 12 Sep 2025 17:43:56 +0200
From: David Hildenbrand <david@...hat.com>
To: Kiryl Shutsemau <kas@...nel.org>, Pedro Falcato <pfalcato@...e.de>
Cc: Johannes Weiner <hannes@...xchg.org>, Nico Pache <npache@...hat.com>,
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Subject: Re: [PATCH v11 00/15] khugepaged: mTHP support

>> Maybe in the Great Glorious Future (how many of those do we have?!) it would
>> be a good idea to take this kinds of things into account. Just because we can
>> map a THP, doesn't mean we should.
>>
>> Shower thought: it might be in these cases especially where the FreeBSD
>> reservation system comes in handy - best effort allocating a THP, but not
>> actually mapping it as such until you really _know_ it is hot - and until
>> then, memory reclaim can just break your THP down if it really needs to.
> 
> This is just silly. All downsides without benefit until maybe later. And
> for short-lived processes the "later" never comes.

Right, that's why I've also been arguing against that (we discussed it 
recently in the THP cabal).

-- 
Cheers

David / dhildenb