From: David Hildenbrand <david@redhat.com>
To: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Kiryl Shutsemau <kas@kernel.org>, Nico Pache <npache@redhat.com>,
linux-mm@kvack.org, linux-doc@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org,
ziy@nvidia.com, baolin.wang@linux.alibaba.com,
Liam.Howlett@oracle.com, ryan.roberts@arm.com, dev.jain@arm.com,
corbet@lwn.net, rostedt@goodmis.org, mhiramat@kernel.org,
mathieu.desnoyers@efficios.com, akpm@linux-foundation.org,
baohua@kernel.org, willy@infradead.org, peterx@redhat.com,
wangkefeng.wang@huawei.com, usamaarif642@gmail.com,
sunnanyong@huawei.com, vishal.moola@gmail.com,
thomas.hellstrom@linux.intel.com, yang@os.amperecomputing.com,
aarcange@redhat.com, raquini@redhat.com,
anshuman.khandual@arm.com, catalin.marinas@arm.com,
tiwai@suse.de, will@kernel.org, dave.hansen@linux.intel.com,
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surenb@google.com, zokeefe@google.com, hannes@cmpxchg.org,
rientjes@google.com, mhocko@suse.com, rdunlap@infradead.org,
hughd@google.com, richard.weiyang@gmail.com,
lance.yang@linux.dev, vbabka@suse.cz, rppt@kernel.org,
jannh@google.com, pfalcato@suse.de
Subject: Re: [PATCH v11 00/15] khugepaged: mTHP support
Date: Mon, 15 Sep 2025 12:25:54 +0200 [thread overview]
Message-ID: <78d75263-e0ab-4dcd-ae97-5c5c9bb10193@redhat.com> (raw)
In-Reply-To: <dcfc7e27-d3c8-4fd0-8b7b-ce8f5051d597@lucifer.local>
>>
>> I would just say "The kernel might decide to use a more conservative approach
>> when collapsing smaller THPs" etc.
>>
>>
>> Thoughts?
>
> Well I've sort of reviewed oppositely there :) well at least that it needs to be
> a hell of a lot clearer (I find that comment really compressed and I just don't
> really understand it).
Right. I think these are just details we should hide from the user. And
in particular, not over-document it so we can more easily change
semantics later.
>
> I guess I didn't think about people reading that and relying on it, so maybe we
> could alternatively make that succinct.
>
> But I think it'd be better to say something like "mTHP collapse cannot currently
> correctly function with half or more of the PTE entries empty, so we cap at just
> below this level" in this case.
IMHO we should just say that the value might be reduced for internal
purposes and that this behavior might change in the future would likely
be good enough.
--
Cheers
David / dhildenb
next prev parent reply other threads:[~2025-09-15 10:26 UTC|newest]
Thread overview: 79+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-09-12 3:27 Nico Pache
2025-09-12 3:27 ` [PATCH v11 01/15] khugepaged: rename hpage_collapse_* to collapse_* Nico Pache
2025-09-12 3:27 ` [PATCH v11 02/15] introduce collapse_single_pmd to unify khugepaged and madvise_collapse Nico Pache
2025-09-12 3:27 ` [PATCH v11 03/15] khugepaged: generalize hugepage_vma_revalidate for mTHP support Nico Pache
2025-09-12 3:27 ` [PATCH v11 04/15] khugepaged: generalize alloc_charge_folio() Nico Pache
2025-09-12 3:28 ` [PATCH v11 05/15] khugepaged: generalize __collapse_huge_page_* for mTHP support Nico Pache
2025-09-12 3:28 ` [PATCH v11 06/15] khugepaged: introduce collapse_max_ptes_none helper function Nico Pache
2025-09-12 13:35 ` Lorenzo Stoakes
2025-09-12 23:26 ` Nico Pache
2025-09-15 10:30 ` Lorenzo Stoakes
2025-09-12 3:28 ` [PATCH v11 07/15] khugepaged: generalize collapse_huge_page for mTHP collapse Nico Pache
2025-09-12 3:28 ` [PATCH v11 08/15] khugepaged: skip collapsing mTHP to smaller orders Nico Pache
2025-09-12 3:28 ` [PATCH v11 09/15] khugepaged: add per-order mTHP collapse failure statistics Nico Pache
2025-09-12 9:35 ` Baolin Wang
2025-09-12 3:28 ` [PATCH v11 10/15] khugepaged: improve tracepoints for mTHP orders Nico Pache
2025-09-12 3:28 ` [PATCH v11 11/15] khugepaged: introduce collapse_allowable_orders helper function Nico Pache
2025-09-12 9:24 ` Baolin Wang
2025-09-12 3:28 ` [PATCH v11 12/15] khugepaged: Introduce mTHP collapse support Nico Pache
2025-09-12 3:28 ` [PATCH v11 13/15] khugepaged: avoid unnecessary mTHP collapse attempts Nico Pache
2025-09-12 3:28 ` [PATCH v11 14/15] khugepaged: run khugepaged for all orders Nico Pache
2025-09-12 3:28 ` [PATCH v11 15/15] Documentation: mm: update the admin guide for mTHP collapse Nico Pache
2025-09-12 8:43 ` [PATCH v11 00/15] khugepaged: mTHP support Lorenzo Stoakes
2025-09-12 12:19 ` Kiryl Shutsemau
2025-09-12 12:25 ` David Hildenbrand
2025-09-12 13:37 ` Johannes Weiner
2025-09-12 13:46 ` David Hildenbrand
2025-09-12 14:01 ` Lorenzo Stoakes
2025-09-12 15:35 ` Pedro Falcato
2025-09-12 15:45 ` Lorenzo Stoakes
2025-09-12 15:15 ` Pedro Falcato
2025-09-12 15:38 ` Kiryl Shutsemau
2025-09-12 15:43 ` David Hildenbrand
2025-09-12 15:44 ` Kiryl Shutsemau
2025-09-12 15:51 ` David Hildenbrand
2025-09-15 13:43 ` Johannes Weiner
2025-09-15 14:45 ` David Hildenbrand
2025-09-12 23:31 ` Nico Pache
2025-09-15 9:22 ` Kiryl Shutsemau
2025-09-15 10:22 ` David Hildenbrand
2025-09-15 10:35 ` Lorenzo Stoakes
2025-09-15 10:39 ` David Hildenbrand
2025-09-15 10:40 ` Lorenzo Stoakes
2025-09-15 10:44 ` David Hildenbrand
2025-09-15 10:48 ` Lorenzo Stoakes
2025-09-15 10:52 ` David Hildenbrand
2025-09-15 10:59 ` Lorenzo Stoakes
2025-09-15 11:10 ` David Hildenbrand
2025-09-15 11:13 ` Lorenzo Stoakes
2025-09-15 11:16 ` David Hildenbrand
2025-09-15 12:16 ` Usama Arif
2025-09-15 10:43 ` Lorenzo Stoakes
2025-09-15 10:52 ` David Hildenbrand
2025-09-15 11:02 ` Lorenzo Stoakes
2025-09-15 11:14 ` David Hildenbrand
2025-09-15 11:23 ` Lorenzo Stoakes
2025-09-15 11:29 ` David Hildenbrand
2025-09-15 11:35 ` Lorenzo Stoakes
2025-09-15 11:45 ` David Hildenbrand
2025-09-15 12:01 ` Kiryl Shutsemau
2025-09-15 12:09 ` Lorenzo Stoakes
2025-09-15 11:41 ` Nico Pache
2025-09-15 12:59 ` David Hildenbrand
2025-09-12 13:47 ` David Hildenbrand
2025-09-12 14:28 ` David Hildenbrand
2025-09-12 14:35 ` Kiryl Shutsemau
2025-09-12 14:56 ` David Hildenbrand
2025-09-12 15:41 ` Kiryl Shutsemau
2025-09-12 15:45 ` David Hildenbrand
2025-09-12 15:51 ` Lorenzo Stoakes
2025-09-12 17:53 ` David Hildenbrand
2025-09-12 18:21 ` Lorenzo Stoakes
2025-09-13 0:28 ` Nico Pache
2025-09-15 10:44 ` Lorenzo Stoakes
2025-09-15 10:25 ` David Hildenbrand [this message]
2025-09-15 10:32 ` Lorenzo Stoakes
2025-09-15 10:37 ` David Hildenbrand
2025-09-15 10:46 ` Lorenzo Stoakes
2025-09-13 0:18 ` Nico Pache
2025-09-12 23:35 ` Nico Pache
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