From: Rik van Riel <riel@surriel.com>
To: "David Hildenbrand (Arm)" <david@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
kernel-team@meta.com, Dave Hansen <dave.hansen@linux.intel.com>,
Peter Zijlstra <peterz@infradead.org>,
Suren Baghdasaryan <surenb@google.com>,
Lorenzo Stoakes <ljs@kernel.org>,
Vlastimil Babka <vbabka@kernel.org>,
"Liam R. Howlett" <liam@infradead.org>,
Mike Rapoport <rppt@kernel.org>, Michal Hocko <mhocko@suse.com>,
Jason Gunthorpe <jgg@ziepe.ca>,
John Hubbard <jhubbard@nvidia.com>, Peter Xu <peterx@redhat.com>,
Matthew Wilcox <willy@infradead.org>,
Usama Arif <usamaarif642@gmail.com>
Subject: Re: [PATCH RFC v4 11/12] mm/gup: batch contiguous PTE-mapped large folios in follow_page_mask()
Date: Mon, 27 Jul 2026 20:37:19 -0400 [thread overview]
Message-ID: <a086dbb3cc9ee8faa638c70bd282ca31c58d402d.camel@surriel.com> (raw)
In-Reply-To: <5490f8b1-d611-4e4d-bd8b-19c0e05698a3@kernel.org>
On Mon, 2026-07-27 at 15:54 +0200, David Hildenbrand (Arm) wrote:
> On 7/25/26 00:29, Rik van Riel wrote:
> >
> > gup_test -L -m 256 -n 65536 -r 16 -t
> > before after
> > 64 kB mTHP 3140 us 412 us (7.6x)
> > 2 MB THP (control) 78 us 76 us
> > 4 kB base (control) 3010 us 3042 us
> >
> > The PMD-mapped 2 MB THP already returns the whole mapping in one
> > step, so
> > it stays fast and unchanged. The 4 kB baseline shows the per-page
> > walk cost
> > that the 64 kB case paid before this change; only the PTE-mapped
> > large
> > folio case improves.
> >
> > Assisted-by: Claude:claude-opus-4.8
> > Signed-off-by: Rik van Riel <riel@surriel.com>
>
> Why is this patch part of this patch set?
>
> This makes perfect sense independently, no?
I'm happy to drop this for now. I think it would
fit in better with another optimization to only
take one refcount per continuously mapped extent
of pages from the same folio.
I can't really untangle it because it modifies
some of the same code as other patches in the
series, but I'm happy to save it for a follow-up.
--
All Rights Reversed.
next prev parent reply other threads:[~2026-07-28 0:39 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-07-24 22:29 [PATCH RFC v4 0/12] mm: use per-VMA lock in __access_remote_vm for improved monitoring reliability Rik van Riel
2026-07-24 22:29 ` [PATCH RFC v4 01/12] x86/mm: add untagged_addr_remote_unlocked() Rik van Riel
2026-07-27 14:50 ` Suren Baghdasaryan
2026-07-28 1:39 ` John Hubbard
2026-07-24 22:29 ` [PATCH RFC v4 02/12] riscv/mm: " Rik van Riel
2026-07-27 14:53 ` Suren Baghdasaryan
2026-07-28 1:44 ` John Hubbard
2026-07-24 22:29 ` [PATCH RFC v4 03/12] mm: rename get_user_page_vma_remote() to get_user_page_lookup_vma() Rik van Riel
2026-07-27 14:58 ` Suren Baghdasaryan
2026-07-24 22:29 ` [PATCH RFC v4 04/12] mm/gup: let check_vma_flags() ignore selected VMA flags Rik van Riel
2026-07-27 15:03 ` Suren Baghdasaryan
2026-07-28 2:40 ` John Hubbard
2026-07-28 14:29 ` Rik van Riel
2026-07-24 22:29 ` [PATCH RFC v4 05/12] mm/gup: add get_user_page_vma() to fault in a page under a held lock Rik van Riel
2026-07-27 16:54 ` Suren Baghdasaryan
2026-07-28 2:45 ` John Hubbard
2026-07-24 22:29 ` [PATCH RFC v4 06/12] mm: use per-VMA lock in __access_remote_vm() for single-VMA accesses Rik van Riel
2026-07-27 18:51 ` Suren Baghdasaryan
2026-07-24 22:29 ` [PATCH RFC v4 07/12] mm: read remote strings under the per-VMA lock Rik van Riel
2026-07-24 22:29 ` [PATCH RFC v4 08/12] selftests/mm: cover /proc/pid/mem access to VM_PFNMAP memory Rik van Riel
2026-07-28 20:58 ` John Hubbard
2026-07-24 22:29 ` [PATCH RFC v4 09/12] mm/gup: build get_user_page_lookup_vma() on get_user_page_vma() Rik van Riel
2026-07-24 22:29 ` [PATCH RFC v4 10/12] mm/gup: pass an end address to follow_page_mask() and return a page count Rik van Riel
2026-07-24 22:29 ` [PATCH RFC v4 11/12] mm/gup: batch contiguous PTE-mapped large folios in follow_page_mask() Rik van Riel
2026-07-27 13:54 ` David Hildenbrand (Arm)
2026-07-28 0:37 ` Rik van Riel [this message]
2026-07-28 19:05 ` David Hildenbrand (Arm)
2026-07-28 20:49 ` Rik van Riel
2026-07-24 22:29 ` [PATCH RFC v4 12/12] selftests/mm: add a slow-GUP content and COW test for mTHP Rik van Riel
2026-07-26 11:56 ` Mike Rapoport
2026-07-27 14:05 ` David Hildenbrand (Arm)
2026-07-28 20:31 ` Rik van Riel
2026-07-27 13:53 ` David Hildenbrand (Arm)
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