From: "David Hildenbrand (Arm)" <david@kernel.org>
To: Baolin Wang <baolin.wang@linux.alibaba.com>, akpm@linux-foundation.org
Cc: catalin.marinas@arm.com, will@kernel.org,
lorenzo.stoakes@oracle.com, ryan.roberts@arm.com,
Liam.Howlett@oracle.com, vbabka@suse.cz, rppt@kernel.org,
surenb@google.com, mhocko@suse.com, riel@surriel.com,
harry.yoo@oracle.com, jannh@google.com, willy@infradead.org,
baohua@kernel.org, dev.jain@arm.com, axelrasmussen@google.com,
yuanchu@google.com, weixugc@google.com, hannes@cmpxchg.org,
zhengqi.arch@bytedance.com, shakeel.butt@linux.dev,
linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 6/6] arm64: mm: implement the architecture-specific test_and_clear_young_ptes()
Date: Mon, 9 Mar 2026 15:39:22 +0100 [thread overview]
Message-ID: <92376758-5bb5-4391-8904-cd0e2f72acf8@kernel.org> (raw)
In-Reply-To: <c607b6fd-a682-4400-a7fd-abe83152db10@linux.alibaba.com>
>>
>> (b) The first pte is !pte_cont(), but some others in there are?
>
> IMO they can’t be handled in a single batch. Since the folio_pte_batch()
> will group consecutive !cont PTEs into one batch and consecutive cont
> PTEs into another (assume all PTEs belong to a single large folio),
> because their PTE entries have different CONT bits.
Interesting, thanks. I thought that folio_pte_batch() would be able to
batch that.
But yes, pte_batch_hint() relies on the CONT bit still being set after a
ptep_get(). I wonder whether we should document somewhere that the arm
implementation depends on that.
This might be something to look into in the future. (make
folio_pte_batch() ignore cont information when comparing and make the
arm implementation be able to deal with that).
Assume we unmapped the last page of a large folio. Ideally, we'd be able
to process the remaining THP pieces (all ptes) in a single operation. I
guess right now it would be two.
--
Cheers,
David
next prev parent reply other threads:[~2026-03-09 14:39 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-06 6:43 [PATCH v3 0/6] support batched checking of the young flag for MGLRU Baolin Wang
2026-03-06 6:43 ` [PATCH v3 1/6] mm: use inline helper functions instead of ugly macros Baolin Wang
2026-03-06 6:43 ` [PATCH v3 2/6] mm: rename ptep/pmdp_clear_young_notify() to ptep/pmdp_test_and_clear_young_notify() Baolin Wang
2026-03-06 6:43 ` [PATCH v3 3/6] mm: rmap: add a ZONE_DEVICE folio warning in folio_referenced() Baolin Wang
2026-03-06 6:43 ` [PATCH v3 4/6] mm: add a batched helper to clear the young flag for large folios Baolin Wang
2026-03-06 6:43 ` [PATCH v3 5/6] mm: support batched checking of the young flag for MGLRU Baolin Wang
2026-03-06 14:44 ` David Hildenbrand (Arm)
2026-03-06 6:43 ` [PATCH v3 6/6] arm64: mm: implement the architecture-specific test_and_clear_young_ptes() Baolin Wang
2026-03-06 14:47 ` David Hildenbrand (Arm)
2026-03-07 1:28 ` Baolin Wang
2026-03-09 14:39 ` David Hildenbrand (Arm) [this message]
2026-03-10 2:51 ` Baolin Wang
2026-03-09 14:40 ` David Hildenbrand (Arm)
2026-03-06 23:20 ` [PATCH v3 0/6] support batched checking of the young flag for MGLRU Andrew Morton
2026-03-07 1:29 ` Baolin Wang
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