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b=Z3kvy/nrtc1ODOdK9vKo/8F+DqtLW8vS+My2lkW4TBV/LV9AqWY20lPS+4Kwd7sKu peVDMJsmgI/nDfqRZw+JKl4cxiyWX+uR1cUh2TtbbKI+C//BubJ30civbuNnWaIQx3 IKjUDwqf7ZA+26d2GK/zjj0DVhoZeeLpEs+eIQTDN7q6VqaauCWLIXiJILerttyumA UhT/nB7R7pLcxh6RuIxudUFVc79gyTia1AysbtMswNY6me1dELYKK8M2hiR+mgCBz1 +rMrHS5id45rCl1uNxMoG4KaNuNc38uGNf4szzh9FP1u9wbc8o9qMPWmQYjQdvg/s8 l8X3BFRa2qWIQ== Message-ID: <54a7e6ff-b3bc-4de4-af26-03fa1400d5f9@kernel.org> Date: Wed, 21 Jan 2026 13:32:29 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 0/8] Introduce a huge-page pre-zeroing mechanism To: David Laight , Li Zhe Cc: akpm@linux-foundation.org, dan.j.williams@intel.com, dave@stgolabs.net, ankur.a.arora@oracle.com, fvdl@google.com, gourry@gourry.net, joao.m.martins@oracle.com, jonathan.cameron@huawei.com, linux-cxl@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, mhocko@suse.com, mjguzik@gmail.com, muchun.song@linux.dev, osalvador@suse.de, raghavendra.kt@amd.com, wangzhou1@hisilicon.com, zhanjie9@hisilicon.com References: <87wm1ih5kb.fsf@oracle.com> <20260120062706.91078-1-lizhe.67@bytedance.com> <20260120094744.5d92e34a@pumpkin> From: "David Hildenbrand (Red Hat)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Stat-Signature: 9fhhnd8ferkxts4ncu3a1rhd1pkhkamu X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 4AF4C180004 X-Rspam-User: X-HE-Tag: 1768998757-30585 X-HE-Meta: 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 LMqKH43N H3DlIlv13XX+O41+hJ3C4v/qYZd+NRdxRtZgkAza+leChUMacQSa0ggjTKcRRfX7GggaQbmr5iSJ/6HLXKLq89Cgcbu69LlRKUsyRZhu/f9ZA5YRudQGukGob2wlwQO1dQh3PHz/fRam65wa+3z+sOSO7DkmzIG08yE+Nw8+wxIPc+7rWGRWCKB8uthsS2ILjU9S2tLnhYq2ug7ra33eHYf65THVOikJ3Pr3+mEJi9cOyfxAW6WER8+az2log1nBFnz0/95F9TvEO500DxqC6E9IFRvl2uVkntUFCjlkBlkbgNlS2FX2SmIpLyuabEKId+xNgNYgjhyxdBNOjuZhddpWD+tyR25WpeLfI 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 1/20/26 10:47, David Laight wrote: > On Tue, 20 Jan 2026 14:27:06 +0800 > "Li Zhe" wrote: > >> In light of the preceding discussion, we appear to have reached the >> following understanding: >> >> (1) At present we prefer to mitigate slow application startup (e.g., >> VM creation) by zeroing huge pages at the moment they are freed >> (init_on_free). The principal benefit is that user space gains the >> performance improvement without deploying any additional user space >> daemon. > > Am I missing something? > If userspace does: > $ program_a; program_b > and pages used by program_a are zeroed when it exits you get the delay > for zeroing all the pages it used before program_b starts. > OTOH if the zeroing is deferred program_b only needs to zero the pages > it needs to start (and there may be some lurking). Can you point me to where was that spelled out as a requirement? > > The only real gain has to come from zeroing pages when the system is idle. > That will give plenty of zeroed pages needed for starting a web browser > from the desktop and also speed up single-threaded things like 'make -j1'. I am strictly against over-engineering any features that hugetlb benefits from only. -- Cheers David