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(p200300d82f06a600a397de1d2f8bb66f.dip0.t-ipconnect.de. [2003:d8:2f06:a600:a397:de1d:2f8b:b66f]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-459e6867193sm249292745e9.6.2025.08.11.03.43.05 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 11 Aug 2025 03:43:06 -0700 (PDT) Message-ID: <6afa5cab-2044-46fb-9afb-8be82fe8a39f@redhat.com> Date: Mon, 11 Aug 2025 12:43:05 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 0/5] add persistent huge zero folio support To: Kiryl Shutsemau Cc: Lorenzo Stoakes , "Pankaj Raghav (Samsung)" , Suren Baghdasaryan , Ryan Roberts , Baolin Wang , Vlastimil Babka , Zi Yan , Mike Rapoport , Dave Hansen , Michal Hocko , Andrew Morton , Thomas Gleixner , Nico Pache , Dev Jain , "Liam R . Howlett" , Jens Axboe , linux-kernel@vger.kernel.org, linux-mm@kvack.org, willy@infradead.org, Ritesh Harjani , linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org, "Darrick J . Wong" , mcgrof@kernel.org, gost.dev@samsung.com, hch@lst.de, Pankaj Raghav References: <20250811084113.647267-1-kernel@pankajraghav.com> <112b4bcd-230a-4482-ae2e-67fa22b3596f@redhat.com> <57bec266-97c4-4292-bd81-93baca737a3c@redhat.com> From: David Hildenbrand Autocrypt: addr=david@redhat.com; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzSREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwZgEEwEIAEICGwMGCwkIBwMCBhUIAgkKCwQW AgMBAh4BAheAAhkBFiEEG9nKrXNcTDpGDfzKTd4Q9wD/g1oFAmgsLPQFCRvGjuMACgkQTd4Q 9wD/g1o0bxAAqYC7gTyGj5rZwvy1VesF6YoQncH0yI79lvXUYOX+Nngko4v4dTlOQvrd/vhb 02e9FtpA1CxgwdgIPFKIuXvdSyXAp0xXuIuRPQYbgNriQFkaBlHe9mSf8O09J3SCVa/5ezKM OLW/OONSV/Fr2VI1wxAYj3/Rb+U6rpzqIQ3Uh/5Rjmla6pTl7Z9/o1zKlVOX1SxVGSrlXhqt kwdbjdj/csSzoAbUF/duDuhyEl11/xStm/lBMzVuf3ZhV5SSgLAflLBo4l6mR5RolpPv5wad GpYS/hm7HsmEA0PBAPNb5DvZQ7vNaX23FlgylSXyv72UVsObHsu6pT4sfoxvJ5nJxvzGi69U s1uryvlAfS6E+D5ULrV35taTwSpcBAh0/RqRbV0mTc57vvAoXofBDcs3Z30IReFS34QSpjvl Hxbe7itHGuuhEVM1qmq2U72ezOQ7MzADbwCtn+yGeISQqeFn9QMAZVAkXsc9Wp0SW/WQKb76 FkSRalBZcc2vXM0VqhFVzTb6iNqYXqVKyuPKwhBunhTt6XnIfhpRgqveCPNIasSX05VQR6/a OBHZX3seTikp7A1z9iZIsdtJxB88dGkpeMj6qJ5RLzUsPUVPodEcz1B5aTEbYK6428H8MeLq NFPwmknOlDzQNC6RND8Ez7YEhzqvw7263MojcmmPcLelYbfOwU0EVcufkQEQAOfX3n0g0fZz Bgm/S2zF/kxQKCEKP8ID+Vz8sy2GpDvveBq4H2Y34XWsT1zLJdvqPI4af4ZSMxuerWjXbVWb T6d4odQIG0fKx4F8NccDqbgHeZRNajXeeJ3R7gAzvWvQNLz4piHrO/B4tf8svmRBL0ZB5P5A 2uhdwLU3NZuK22zpNn4is87BPWF8HhY0L5fafgDMOqnf4guJVJPYNPhUFzXUbPqOKOkL8ojk CXxkOFHAbjstSK5Ca3fKquY3rdX3DNo+EL7FvAiw1mUtS+5GeYE+RMnDCsVFm/C7kY8c2d0G NWkB9pJM5+mnIoFNxy7YBcldYATVeOHoY4LyaUWNnAvFYWp08dHWfZo9WCiJMuTfgtH9tc75 7QanMVdPt6fDK8UUXIBLQ2TWr/sQKE9xtFuEmoQGlE1l6bGaDnnMLcYu+Asp3kDT0w4zYGsx 5r6XQVRH4+5N6eHZiaeYtFOujp5n+pjBaQK7wUUjDilPQ5QMzIuCL4YjVoylWiBNknvQWBXS lQCWmavOT9sttGQXdPCC5ynI+1ymZC1ORZKANLnRAb0NH/UCzcsstw2TAkFnMEbo9Zu9w7Kv AxBQXWeXhJI9XQssfrf4Gusdqx8nPEpfOqCtbbwJMATbHyqLt7/oz/5deGuwxgb65pWIzufa N7eop7uh+6bezi+rugUI+w6DABEBAAHCwXwEGAEIACYCGwwWIQQb2cqtc1xMOkYN/MpN3hD3 AP+DWgUCaCwtJQUJG8aPFAAKCRBN3hD3AP+DWlDnD/4k2TW+HyOOOePVm23F5HOhNNd7nNv3 Vq2cLcW1DteHUdxMO0X+zqrKDHI5hgnE/E2QH9jyV8mB8l/ndElobciaJcbl1cM43vVzPIWn 01vW62oxUNtEvzLLxGLPTrnMxWdZgxr7ACCWKUnMGE2E8eca0cT2pnIJoQRz242xqe/nYxBB /BAK+dsxHIfcQzl88G83oaO7vb7s/cWMYRKOg+WIgp0MJ8DO2IU5JmUtyJB+V3YzzM4cMic3 bNn8nHjTWw/9+QQ5vg3TXHZ5XMu9mtfw2La3bHJ6AybL0DvEkdGxk6YHqJVEukciLMWDWqQQ RtbBhqcprgUxipNvdn9KwNpGciM+hNtM9kf9gt0fjv79l/FiSw6KbCPX9b636GzgNy0Ev2UV m00EtcpRXXMlEpbP4V947ufWVK2Mz7RFUfU4+ETDd1scMQDHzrXItryHLZWhopPI4Z+ps0rB CQHfSpl+wG4XbJJu1D8/Ww3FsO42TMFrNr2/cmqwuUZ0a0uxrpkNYrsGjkEu7a+9MheyTzcm vyU2knz5/stkTN2LKz5REqOe24oRnypjpAfaoxRYXs+F8wml519InWlwCra49IUSxD1hXPxO WBe5lqcozu9LpNDH/brVSzHCSb7vjNGvvSVESDuoiHK8gNlf0v+epy5WYd7CGAgODPvDShGN g3eXuA== Organization: Red Hat In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: sKmJX0qgr8jWjFxpMHb3-kkFIEu0-f9NxJtP6ZVRGD8_1754908988 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Stat-Signature: afeernw9hpmccbe3kbcf3asa4zajpof9 X-Rspam-User: X-Rspamd-Queue-Id: 2EC0640004 X-Rspamd-Server: rspam02 X-HE-Tag: 1754908991-772972 X-HE-Meta: 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 1wmYl1La 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 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 11.08.25 12:36, Kiryl Shutsemau wrote: > On Mon, Aug 11, 2025 at 12:21:23PM +0200, David Hildenbrand wrote: >> On 11.08.25 12:17, Kiryl Shutsemau wrote: >>> On Mon, Aug 11, 2025 at 11:09:24AM +0100, Lorenzo Stoakes wrote: >>>> On Mon, Aug 11, 2025 at 11:07:48AM +0100, Kiryl Shutsemau wrote: >>>>> >>>>> Well, my worry is that 2M can be a high tax for smaller machines. >>>>> Compile-time might be cleaner, but it has downsides. >>>>> >>>>> It is also not clear if these users actually need physical HZP or virtual >>>>> is enough. Virtual is cheap. >>>> >>>> The kernel config flag (default =N) literally says don't use unless you >>>> have plenty of memory :) >>>> >>>> So this isn't an issue. >>> >>> Distros use one-config-fits-all approach. Default N doesn't help >>> anything. >> >> You'd probably want a way to say "use the persistent huge zero folio if you >> machine has more than X Gigs". That's all reasonable stuff that can be had >> on top of this series. > > We have 'totalram_pages() < (512 << (20 - PAGE_SHIFT))' check in > hugepage_init(). It can [be abstracted out and] re-used. I'll note that e.g., RHEL 10 already has a minimum RAM requirement of 2 GiB. I think for Fedora it's 1 GiB, with the recommendation of having at least 2 GiB. What might be reasonable is having a kconfig option where one (distro) can define the minimum RAM size for the persistent huge zero folio, and then checking against totalram_pages() during boot. But again, I think this is something that goes on top of this series. (it might also be interesting to allow for disabling the persistent huge zero folio through a cmdline option) -- Cheers, David / dhildenb