From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 48F16FC5914 for ; Thu, 26 Feb 2026 09:17:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=9GxSMZHScUxIn+8E4CzIuG4hlJVrAkuR5XrUsdWo5VE=; b=kCewikKaR8tNBDuKLbEQe6Q2RZ wHKawv4qOjb+n5lrKJKsNXSg0+TC7e6kcjIPGbDpfWQrMqRcNhox7V+PBf3XysmExL/xdnlymbNFw bERSD1pCNyFs2Uesj9oLYnQMuNYtXq/btppQ59XMb1jWutIEhg9Tc+Aujp+3hTZzSJqRLFXM4TBPg vZkBWWYGUTaaVFddq9FgxDkaGNkJ6vExPJRArUuv5t68upQytYK0jycOammEMNMWbV4gHLSpK93IY WorB1Qd87qprekYvbb83QsVRgfabdAsgLV2pX+9E2lSxS+IeXvlfN3QgyP4hvOOhvoUEfHUEOGDhz Hp5aAWbg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vvXM1-00000005kbt-2VSS; Thu, 26 Feb 2026 09:08:17 +0000 Received: from sea.source.kernel.org ([2600:3c0a:e001:78e:0:1991:8:25]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1vvXLz-00000005kbW-3t8z for linux-arm-kernel@lists.infradead.org; Thu, 26 Feb 2026 09:08:16 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id 606AB43E7B; Thu, 26 Feb 2026 09:08:15 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D10C7C19423; Thu, 26 Feb 2026 09:08:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1772096895; bh=y11g85XCUlJsP2pyz2TMzKQd4wTjpzRaV9t1RrP34Is=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=fz2NDguc1AOocd74h8/J/h7ht36vcblPdeyl1ZjskZ7ogkSk1JEeX1JSL2GS/wXMD 6/3VKmcLGkdTHvpkKnUlhY73qSQgkI5UMSA6TGcPqpCL0tKrQUGPgodhruXcwy/clE 93idkfQEhc3SibeIbHqrEUcxXp8pfLXx8QYAq78BeGCktAGudCKsWyRE4AiL0GO8ev cLqSWYlL/AjfUAzOViDYpfJSWLs1xCAE9r6rP5XeufpTYz0/WRlB8AbtvUE/7v4qDC Uu0PjfRGzRPH0v0yfeKQrnUKcz22mqwEiAXAqSAiwctDwofLuelBp+jKmeKvkL1aID OV9ExLj0EQ3kA== Message-ID: <2599bc1e-1f8e-46bc-afea-4cb8f657545b@kernel.org> Date: Thu, 26 Feb 2026 10:08:06 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 4/5] mm: support batched checking of the young flag for MGLRU To: Baolin Wang , 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 References: <84d2426c63c1eafeaa0cfbad7c5cc11e9c11b980.1771897150.git.baolin.wang@linux.alibaba.com> <2e7a1e24-3616-4b79-b943-b5f7efde2d31@kernel.org> <0871edb9-08a2-46a0-ade6-af842a12e0d3@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-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260226_010816_008235_6CBC0A9A X-CRM114-Status: GOOD ( 13.24 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org >> >>> +            pte_t pteval = ptep_get(pvmw.pte); >> >> I wonder if there could be a way to avoid this ptep_get() by letting >> page_vma_mapped_walk() just provide the last value it used (in >> check_pte() I guess). Something for another patch. > > Well, we’d need to add a new field to ‘struct page_vma_mapped_walk’ to > store the last value (e.g., pvmw.pteval), Yes. > but this makes me wonder if it > is worth adding a new field just to avoid a lightweight read (which > should have no obvious performance impact). You recall that ptep_get() on arm64 is not that lightweight due to con-pte? :) But yeah, something for another day. [...] >> >> What is "batched"? Did you mean "nr_ptes" ? Or just the initial value >> for "nr" ? > > There is already an 'nr' variable in this function. "nr_ptes" sounds > good to me, and will use it. You can just use "nr" here and reuse it for the existing variable? Both have the same semantics (nr of ptes / pages), so having a single value might cause less confusion. -- Cheers, David