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b=IgOnLcroN+Cq4+uoc9rtF5U2JdkUFn/isXguriJYr4aQzvF25A5VeON8B+f31ceaY sxF4gZK9IF/xbEJi8UmLT5YkJqdECPNh7wKqzOYAy+udOV+IQEhKFAet4DKkkeRx9X X106S6MIa49lZe6PUl6PJ2LzW+cudcfxt3A1T4Xk= Date: Fri, 6 Mar 2026 15:20:42 -0800 From: Andrew Morton To: Baolin Wang Cc: david@kernel.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, 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 0/6] support batched checking of the young flag for MGLRU Message-Id: <20260306152042.8516ec644e95e9a23df30e5f@linux-foundation.org> In-Reply-To: References: X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Queue-Id: D2B354000C X-Rspamd-Server: rspam08 X-Stat-Signature: 3k5g78f4z7agrr63j8wnpppti3hoa4re X-HE-Tag: 1772839245-386819 X-HE-Meta: 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 6KL8IE3e exC3lnjJVvIsx8j+ldrmGvAR35ZUZsV/6gDPMGYGpsDHdmPk0qzb3STbJAh40ZCkPwQmaygxMGiDizOPzKSYnMeKXRg7xuNSXyce9X/ue14P+wHcsQ6lCAPOC1ZPBrNrirVIFixSEaJTZdy/QK6zSbUxLHwK1DooSjnGdkmh3cjGFwA4yGk3X53pKugzixRI3DeKigpv+5O8SDXvrvawYWmPNMjuTz/pDsWReyZTiw1Vkog/45EeH5QeA0bcVyW57NY27u/sc8on/K4Ehz2c9qf6tyntGtNVGIGwXzbPe4ldXbpQ= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, 6 Mar 2026 14:43:36 +0800 Baolin Wang wrote: > This is a follow-up to the previous work [1], to support batched checking > of the young flag for MGLRU. > > Similarly, batched checking of young flag for large folios can improve > performance during large-folio reclamation when MGLRU is enabled. I > observed noticeable performance improvements (see patch 5) on an Arm64 > machine that supports contiguous PTEs. All mm-selftests are passed. Thanks, I updated mm-new with this. > Changes from v2: > v2: https://lore.kernel.org/all/cover.1772185080.git.baolin.wang@linux.alibaba.com/ > - Update the commit message of patch 5 (per David). > - Fix some coding style issues (per David). > - Remove 'cur_pte' variable in lru_gen_look_around() (per David). > - Move 'ptes += nr;' to the suitable place in folio_referenced_one() (per David). > - Add acked tag from David. Thanks. > Here's how v3 altered mm.git: include/linux/pgtable.h | 3 +-- mm/rmap.c | 2 +- mm/vmscan.c | 11 +++++------ 3 files changed, 7 insertions(+), 9 deletions(-) --- a/include/linux/pgtable.h~b +++ a/include/linux/pgtable.h @@ -1124,8 +1124,7 @@ static inline int clear_flush_young_ptes * Returns: whether any PTE was young. */ static inline int test_and_clear_young_ptes(struct vm_area_struct *vma, - unsigned long addr, pte_t *ptep, - unsigned int nr) + unsigned long addr, pte_t *ptep, unsigned int nr) { int young = 0; --- a/mm/rmap.c~b +++ a/mm/rmap.c @@ -964,7 +964,6 @@ static bool folio_referenced_one(struct pte_t pteval = ptep_get(pvmw.pte); nr = folio_pte_batch(folio, pvmw.pte, pteval, max_nr); - ptes += nr; } if (lru_gen_enabled() && pvmw.pte) { @@ -982,6 +981,7 @@ static bool folio_referenced_one(struct WARN_ON_ONCE(1); } + ptes += nr; pra->mapcount -= nr; /* * If we are sure that we batched the entire folio, --- a/mm/vmscan.c~b +++ a/mm/vmscan.c @@ -4201,7 +4201,6 @@ bool lru_gen_look_around(struct page_vma struct lruvec *lruvec; struct lru_gen_mm_state *mm_state; unsigned long max_seq; - pte_t *cur_pte; int gen; lockdep_assert_held(pvmw->ptl); @@ -4247,10 +4246,10 @@ bool lru_gen_look_around(struct page_vma pte -= (addr - start) / PAGE_SIZE; - for (i = 0, addr = start, cur_pte = pte; addr != end; - i += nr, cur_pte += nr, addr += nr * PAGE_SIZE) { + for (i = 0, addr = start; addr != end; + i += nr, pte += nr, addr += nr * PAGE_SIZE) { unsigned long pfn; - pte_t ptent = ptep_get(cur_pte); + pte_t ptent = ptep_get(pte); nr = 1; pfn = get_pte_pfn(ptent, vma, addr, pgdat); @@ -4264,11 +4263,11 @@ bool lru_gen_look_around(struct page_vma if (folio_test_large(folio)) { const unsigned int max_nr = (end - addr) >> PAGE_SHIFT; - nr = folio_pte_batch_flags(folio, NULL, cur_pte, &ptent, + nr = folio_pte_batch_flags(folio, NULL, pte, &ptent, max_nr, FPB_MERGE_YOUNG_DIRTY); } - if (!test_and_clear_young_ptes_notify(vma, addr, cur_pte, nr)) + if (!test_and_clear_young_ptes_notify(vma, addr, pte, nr)) continue; if (last != folio) { _