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Thu, 16 Oct 2025 09:06:32 +0800 (CST) Received: from dggpemf100008.china.huawei.com (unknown [7.185.36.138]) by mail.maildlp.com (Postfix) with ESMTPS id 814DA140156; Thu, 16 Oct 2025 09:07:17 +0800 (CST) Received: from [10.174.177.243] (10.174.177.243) by dggpemf100008.china.huawei.com (7.185.36.138) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Thu, 16 Oct 2025 09:07:16 +0800 Message-ID: Date: Thu, 16 Oct 2025 09:07:13 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 2/3] mm: mprotect: avoid unnecessary struct page accessing if pte_protnone() To: David Hildenbrand , Lorenzo Stoakes CC: Andrew Morton , , Zi Yan , Baolin Wang , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , , Sidhartha Kumar References: <20251015123516.2703660-1-wangkefeng.wang@huawei.com> <20251015123516.2703660-3-wangkefeng.wang@huawei.com> <2c2a9527-e52b-46db-ac8b-b13f4ba6d0cb@redhat.com> Content-Language: en-US From: Kefeng Wang In-Reply-To: <2c2a9527-e52b-46db-ac8b-b13f4ba6d0cb@redhat.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.177.243] X-ClientProxiedBy: kwepems500002.china.huawei.com (7.221.188.17) To dggpemf100008.china.huawei.com (7.185.36.138) X-Stat-Signature: 7weg9birsenyx5ozb8byenffmw5e9u1f X-Rspamd-Queue-Id: 60F35180008 X-Rspamd-Server: rspam06 X-Rspam-User: X-HE-Tag: 1760576842-152530 X-HE-Meta: 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 +Lpqj5Gh IqnCdolW/p9w+b8H764ZT3xnaDiYl4Gr2Nb6H6EXNk2asFzh5jmjNp+iNbfB06mlHI4jndH514UhnU3x7WvpOVjAINw1sIx9kDgRms2VYnU3qj6Tu3q9wgE+GbbKkduF9GnwQDnWBVR3J52TlhpqGSApUwZTC6ba5MiIQnKO4zRrsbDMptmX4MCw1Is5tieN0KcHHNgWfsHCUEt6yERxqokwXc+P2eKQkgnn4vEkLfF1EcEyldGjRaFQEMg8F8/q5OKUP3h4tyFpdARmkhK0AxJvaG2niVNmf0tWaJ96KPUmJZxZSdUEBhPm6uOMpftBuI7pb8VY4JhVsvRTqD8v4mQCeYTaD3rZOtVgQx7ePU5OX9KY= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 2025/10/16 1:45, David Hildenbrand wrote: > On 15.10.25 17:43, Lorenzo Stoakes wrote: >> On Wed, Oct 15, 2025 at 08:35:15PM +0800, Kefeng Wang wrote: >>> If the pte_protnone() is true, we could avoid unnecessary struct page >>> accessing and reduce cache footprint when scanning page tables for prot >>> numa, the performance test of pmbench memory accessing benchmark >>> should be benifit, see more commit a818f5363a0e ("autonuma: reduce cache >>> footprint when scanning page tables"). >> >> Hm should benefit? But you've not tested it? Seems like rather than >> guessing you should actually give data. Otherwise I don't know why we're >> referencing a benchmark. > Yes, I don't test it, just find the above commit which does same thing before and it shows benefit in a benchmark. > I guess it might be harder to quantify, but theoretically it makes sense > to me to just skip in any case. > > ... and it enables patch #3, which is nice :) > My initial goal was to skip unnecessary steps for pmd folio when prot numa.