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Received: from 30.97.56.69(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0W62Fj9e_1715147148) by smtp.aliyun-inc.com; Wed, 08 May 2024 13:45:50 +0800 Message-ID: Date: Wed, 8 May 2024 13:45:48 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 0/8] add mTHP support for anonymous shmem To: Ryan Roberts , akpm@linux-foundation.org, hughd@google.com Cc: willy@infradead.org, david@redhat.com, ioworker0@gmail.com, wangkefeng.wang@huawei.com, ying.huang@intel.com, 21cnbao@gmail.com, shy828301@gmail.com, ziy@nvidia.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: From: Baolin Wang In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: E64E0180015 X-Rspam-User: X-Rspamd-Server: rspam04 X-Stat-Signature: xb3kehh6m5wbecygnjtgici7skya1wz7 X-HE-Tag: 1715147154-709096 X-HE-Meta: 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 pi+SLf6b abpfz9pApFDwJg4q04vvNogufRzoE1gNM/UojldoIJTI4oXoOWaT6Krdbj9HP4gehrAWsQAO0awIppdRPasau1o0QLlCjWOdmGjNu7ARQBn6ulg/CiYdiXtlIpJdzDRE3PqFchYgq4zac4ciJrjV43R1UOyVwDIC4tdDRHd+CGnx8FwDhp13uIOEiJnGIY5JiocyLzCLXjJ4hzurfvOp7CIgkBQFM/9Lu2RhrvQUogOYQgNK2l+NnMCUH/dgHPKM2/TlIBLHqC7pTuNZGDFCOTy/o0ui5vuUx9EWo1b2Gu5RIYJ4= 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 2024/5/7 18:20, Ryan Roberts wrote: > On 06/05/2024 09:46, Baolin Wang wrote: >> Anonymous pages have already been supported for multi-size (mTHP) allocation >> through commit 19eaf44954df, that can allow THP to be configured through the >> sysfs interface located at '/sys/kernel/mm/transparent_hugepage/hugepage-XXkb/enabled'. >> >> However, the anonymous shared pages will ignore the anonymous mTHP rule >> configured through the sysfs interface, and can only use the PMD-mapped >> THP, that is not reasonable. Many implement anonymous page sharing through >> mmap(MAP_SHARED | MAP_ANONYMOUS), especially in database usage scenarios, >> therefore, users expect to apply an unified mTHP strategy for anonymous pages, >> also including the anonymous shared pages, in order to enjoy the benefits of >> mTHP. For example, lower latency than PMD-mapped THP, smaller memory bloat >> than PMD-mapped THP, contiguous PTEs on ARM architecture to reduce TLB miss etc. >> >> The primary strategy is similar to supporting anonymous mTHP. Introduce >> a new interface '/mm/transparent_hugepage/hugepage-XXkb/shmem_enabled', >> which can have all the same values as the top-level > > Didn't we agree that "force" would not be supported for now, and would return an > error when attempting to set for a non-PMD-size hugepage-XXkb/shmem_enabled (or > indirectly through inheritance)? Yes. Sorry, I did not explain it in detail in the cover letter. Please see patch 5 you already commented.