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b=bEW94uy60EpA9Ru8lqDh5UOzDaIQlgGRMV8+NwznuGo65Q9z9BhnfiBGlJIaC8f8+ KStR0JdtTGHifsHppa6ZjoGsOIzsq2ZbJG1fZPZCe6Dl+oazZZ6odf1vu0EX31YGMB 5AP+wQ/f1Pajb33PbNbH2y6Q8ZT7G51D47VjkmVszHHhfgsibjQnFPBlFa3wTXkQK0 OMgqpYegwDzSsmLtZTJaFKiPUL3yfa8U/EVqDlp/4c9QMuxsVFLIvRQtXZu5tJIrjg SAFgTnUHbUNeZS95KQ3cNoPAZy2cWkNSWAUfGg976omsBoDVw8XDO9LEk+XNJSPszH 5KBEp+CJU7hTA== Message-ID: <43831628-a00f-4292-9797-cb96a029bb00@kernel.org> Date: Tue, 10 Mar 2026 09:17:54 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v6 1/5] mm: rmap: support batched checks of the references for large folios To: Baolin Wang , Barry Song <21cnbao@gmail.com> Cc: akpm@linux-foundation.org, 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, dev.jain@arm.com, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org References: <12132694536834262062d1fb304f8f8a064b6750.1770645603.git.baolin.wang@linux.alibaba.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 8B0B6180004 X-Stat-Signature: ycatco3fd989fzq65r9g5hhw6y7eweu6 X-HE-Tag: 1773130683-746378 X-HE-Meta: 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 mReEJkvO W+V18Qjjl3u09qB+x0j7R7HOHc5f/YgEZSWXGAgejWj7WrlChvCKpfPjPxCpl3RkGA4SFcZ90XVDfMAmd99T/VXJDFrlp6ExOtMbUXLVQGnf94GtavXSeOmhgtYhOKU3mJbxfXGw4EuiZAwKMjvGucHR8rLkv94EEbQfx8CF9GyLP9WodYzNkLAvEpdWtBjHiogWKAqKJR1zBXE6wBKbqQkdiemxIJrtcIDRjaJqwH7fZIC/lp6YTlZrYMF+3TRl1HjCdPlmqDyZ3NKaoDKkMNiN9+Y0iclIyzfxxTk6ykc9suyfOcmJGe/hukA== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 3/10/26 02:37, Baolin Wang wrote: > > > On 3/7/26 4:02 PM, Barry Song wrote: >> On Sat, Mar 7, 2026 at 10:22 AM Baolin Wang >> wrote: >>> >>> >>> >>> >>> Thanks. >>> >>> >>> Yes. In addition, this will involve many architectures’ implementations >>> and their differing TLB flush mechanisms, so it’s difficult to make a >>> reasonable per-architecture measurement. If any architecture has a more >>> efficient flush method, I’d prefer to implement an architecture‑specific >>> clear_flush_young_ptes(). >> >> Right! Since TLBI is usually quite expensive, I wonder if a generic >> implementation for architectures lacking clear_flush_young_ptes() >> might benefit from something like the below (just a very rough idea): >> >> int clear_flush_young_ptes(struct vm_area_struct *vma, >>                  unsigned long addr, pte_t *ptep, unsigned int nr) >> { >>          unsigned long curr_addr = addr; >>          int young = 0; >> >>          while (nr--) { >>                  young |= ptep_test_and_clear_young(vma, curr_addr, >> ptep); >>                  ptep++; >>                  curr_addr += PAGE_SIZE; >>          } >> >>          if (young) >>                  flush_tlb_range(vma, addr, curr_addr); >>          return young; >> } > > I understand your point. I’m concerned that I can’t test this patch on > every architecture to validate the benefits. Anyway, let me try this on > my X86 machine first. In any case, please make that a follow-up patch :) -- Cheers, David