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[2003:d8:2f3e:5900:27aa:5f4a:b65c:3d3c]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-442cd3b7f18sm31317155e9.40.2025.05.08.02.18.35 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 08 May 2025 02:18:37 -0700 (PDT) Message-ID: <78bc6a1b-164e-4925-a624-a271a4499364@redhat.com> Date: Thu, 8 May 2025 11:18:35 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 1/3] driver/base: Optimize memory block registration to reduce boot time To: Mike Rapoport Cc: Oscar Salvador , Donet Tom , Zi Yan , Greg Kroah-Hartman , Andrew Morton , rafael@kernel.org, Danilo Krummrich , Ritesh Harjani , Jonathan Cameron , Alison Schofield , Yury Norov , Dave Jiang , linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <188fbfba-afb4-4db7-bbba-7689a96be931@redhat.com> <74c500dd-8d1c-4177-96c7-ddd51ca77306@redhat.com> <8180a50d-eebe-4f9b-9ce8-d886654a992d@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/g1oFAl8Ox4kFCRKpKXgACgkQTd4Q 9wD/g1oHcA//a6Tj7SBNjFNM1iNhWUo1lxAja0lpSodSnB2g4FCZ4R61SBR4l/psBL73xktp rDHrx4aSpwkRP6Epu6mLvhlfjmkRG4OynJ5HG1gfv7RJJfnUdUM1z5kdS8JBrOhMJS2c/gPf wv1TGRq2XdMPnfY2o0CxRqpcLkx4vBODvJGl2mQyJF/gPepdDfcT8/PY9BJ7FL6Hrq1gnAo4 3Iv9qV0JiT2wmZciNyYQhmA1V6dyTRiQ4YAc31zOo2IM+xisPzeSHgw3ONY/XhYvfZ9r7W1l pNQdc2G+o4Di9NPFHQQhDw3YTRR1opJaTlRDzxYxzU6ZnUUBghxt9cwUWTpfCktkMZiPSDGd KgQBjnweV2jw9UOTxjb4LXqDjmSNkjDdQUOU69jGMUXgihvo4zhYcMX8F5gWdRtMR7DzW/YE BgVcyxNkMIXoY1aYj6npHYiNQesQlqjU6azjbH70/SXKM5tNRplgW8TNprMDuntdvV9wNkFs 9TyM02V5aWxFfI42+aivc4KEw69SE9KXwC7FSf5wXzuTot97N9Phj/Z3+jx443jo2NR34XgF 89cct7wJMjOF7bBefo0fPPZQuIma0Zym71cP61OP/i11ahNye6HGKfxGCOcs5wW9kRQEk8P9 M/k2wt3mt/fCQnuP/mWutNPt95w9wSsUyATLmtNrwccz63XOwU0EVcufkQEQAOfX3n0g0fZz 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+DWgUCXw7HsgUJEqkpoQAKCRBN3hD3AP+DWrrpD/4qS3dyVRxDcDHIlmguXjC1Q5tZTwNB boaBTPHSy/Nksu0eY7x6HfQJ3xajVH32Ms6t1trDQmPx2iP5+7iDsb7OKAb5eOS8h+BEBDeq 3ecsQDv0fFJOA9ag5O3LLNk+3x3q7e0uo06XMaY7UHS341ozXUUI7wC7iKfoUTv03iO9El5f XpNMx/YrIMduZ2+nd9Di7o5+KIwlb2mAB9sTNHdMrXesX8eBL6T9b+MZJk+mZuPxKNVfEQMQ a5SxUEADIPQTPNvBewdeI80yeOCrN+Zzwy/Mrx9EPeu59Y5vSJOx/z6OUImD/GhX7Xvkt3kq Er5KTrJz3++B6SH9pum9PuoE/k+nntJkNMmQpR4MCBaV/J9gIOPGodDKnjdng+mXliF3Ptu6 3oxc2RCyGzTlxyMwuc2U5Q7KtUNTdDe8T0uE+9b8BLMVQDDfJjqY0VVqSUwImzTDLX9S4g/8 kC4HRcclk8hpyhY2jKGluZO0awwTIMgVEzmTyBphDg/Gx7dZU1Xf8HFuE+UZ5UDHDTnwgv7E th6RC9+WrhDNspZ9fJjKWRbveQgUFCpe1sa77LAw+XFrKmBHXp9ZVIe90RMe2tRL06BGiRZr jPrnvUsUUsjRoRNJjKKA/REq+sAnhkNPPZ/NNMjaZ5b8Tovi8C0tmxiCHaQYqj7G2rgnT0kt WNyWQQ== Organization: Red Hat In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: VDJ7p8_6XXYA5ZQQniPIlwYlUEowXuXwnSsJm6fXR50_1746695918 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 09031A0002 X-Rspam-User: X-Rspamd-Server: rspam07 X-Stat-Signature: 7orxbkqtkdjowjj3kzbz3rc4yuyh3gdb X-HE-Tag: 1746695922-683836 X-HE-Meta: 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 Rsgtl3Pc 27Zt5JQhicIHVrPQuXnEim8SONqQvw2iCYRaoAJf7l5EVI64JVU3O8Wrt3LIUxFUyFas1Ph//oJL2EZcrqc+SD9l54lZvUmumN740F3BlQYAFljqBx/ks4TPUAM0sorT+exOw/+/BSZsfaxp0MkUUHQHTE1NWSsmrLdRf5dsJO+RZaNMwaHQvc+A1i3EzllKFx4X5h0hCqKpWjAYZ33LhgdCconXBCDpLIOLkFffW39GPnHgqULq2cvZ1I0lbRvMpR1tP1BnxpHLuOfUieH8sX/pvoQF2WuelSU7L4iDHaFzlaUGM624PkAEjxfd0wAGbDCw3xzhFXQj2BN4xZkEXQn2r8263DjdlEshImj4fpU0O4wclPqJNtOAtaaf2hg4Zgb7beEythrFc8/jEhp58DRCg5sZ6AIg8O4g8FGKjabty86o/J5U59YPOpTjp6oFPhUamh9diDDkDFJj96coPXpNeKIHE4fAt6WJH 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 05.05.25 15:24, Mike Rapoport wrote: > On Mon, May 05, 2025 at 10:18:43AM +0200, David Hildenbrand wrote: >> On 05.05.25 09:53, Mike Rapoport wrote: >>> On Mon, May 05, 2025 at 09:38:43AM +0200, David Hildenbrand wrote: >>>> On 05.05.25 09:28, Oscar Salvador wrote: >>>>> On Mon, May 05, 2025 at 09:16:48AM +0200, David Hildenbrand wrote: >>>>>> memory hotplug code never calls register_one_node(), unless I am missing >>>>>> something. >>>>>> >>>>>> During add_memory_resource(), we call __try_online_node(nid, false), meaning >>>>>> we skip register_one_node(). >>>>>> >>>>>> The only caller of __try_online_node(nid, true) is try_online_node(), called >>>>>> from CPU hotplug code, and I *guess* that is not required. >>>>> >>>>> Well, I guess this is because we need to link the cpus to the node. >>>>> register_one_node() has two jobs: 1) register cpus belonging to the node >>>>> and 2) register memory-blocks belonging to the node (if any). >>>> >>>> Ah, via __register_one_node() ... >>>> >>>> I would assume that an offline node >>>> >>>> (1) has no memory >>>> (2) has no CPUs >>>> >>>> When we *hotplug* either memory or CPUs, and we first online the node, there >>>> is nothing to register. Because if there would be something, the node would >>>> already be online. >>>> >>>> In particular, try_offline_node() will only offline a node if >>>> >>>> (A) No present pages: No pages are spanned anymore. This includes >>>> offline memory blocks. >>>> (B) No present CPUs. >>>> >>>> But maybe there is some case that I am missing ... >>> >>> I actually hoped you and Oscar know how that stuff works :) >> >> Well, I know how the memory side works, but the CPU side is giving me a hard >> time :) >> >>> >>> I tried to figure what is going on there and it all looks really convoluted. >> >> Jap ... >> >>> >>> So, on boot we have >>> cpu_up() -> >>> try_online_node() -> >>> bails out because all nodes are online (at least on >>> x86 AFAIU, see 1ca75fa7f19d ("arch/x86/mm/numa: Do >>> not initialize nodes twice")) >>> node_dev_init()i -> >>> register_one_node() -> >>> this one can use __register_one_node() and loop >>> over memblock regions. >>> >>> And for the hotplug/unplug path, it seems that >>> register_memory_blocks_under_node(MEMINIT_EARLY) is superfluous, because if >>> a node had memory it wouldn't get offlined, and if we are hotplugging an >>> node with memory and cpus, memory hotplug anyway calls >>> register_memory_blocks_under_node_hotplug(). >>> >>> So, IMHO, register_one_node() should not call >>> register_memory_blocks_under_node() at all, but again, I might have missed >>> something :) >> >> Hm, but someone has to create these links for the memory blocks. > > My understanding that the links for the memory blocks during hotplug are created in > > add_memory_resource() > register_memory_blocks_under_node() Yes, during hotplug it's exactly that, after registering the node + setting it online. > > So register_one_node() only calls register_memory_blocks_under_node() when > there are no actual memory resources under that node, isn't it? Except in early boot. That's why register_one_node() has: register_memory_blocks_under_node(nid, start_pfn, end_pfn, MEMINIT_EARLY); ^ early :) And that is triggered by node_dev_init()->register_one_node() > > Then we can drop the call to register_memory_blocks_under_node() from > register_one_node() and add creation of memory blocks to node_dev_init(), > i.e. > > node_dev_init() > for_each_node(nid) > __register_one_node(nid) > for_each_mem_region() > /* create memory block if node matches */ Yes exactly, that makes sense. -- Cheers, David / dhildenb