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[2003:cb:c70d:1f00:7a4e:8f21:98db:baef]) by smtp.gmail.com with ESMTPSA id x5-20020a5d6b45000000b003472489d26fsm17156797wrw.19.2024.04.24.05.52.42 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 24 Apr 2024 05:52:42 -0700 (PDT) Message-ID: Date: Wed, 24 Apr 2024 14:52:41 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [LSF/MM/BPF TOPIC] SLAB BOF To: Matthew Wilcox , lsf-pc@lists.linux-foundation.org, linux-mm@kvack.org References: 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-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 9C01940005 X-Stat-Signature: eo7iinjgser9xo4mzuec6zrid6i8ta5x X-HE-Tag: 1713963166-446444 X-HE-Meta: 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 o75mCTti fDNcf2ii3adW99sKruXBF7niPmxFGUx2nSnvIK7JObniCnvxYMVBZvgvsPUBzH8NF9iU/N+QNFf5c71ZAv+ARNMLDjn98d9jGpr6VwZRfgZCWM+ftN6aZDLxN55V0G9WvGlcNPaXhk6DG/7eB3CGHKODs/VwSzFwRk/ykaRaZ03tkfo/vnwZY0uquUSbVwnA5JEgz2KL9gGFWCh5B+TT3GbeREt2LJ+/4PYpctcQk9mn6HFJ5nr9rooCrBkIi0IkGUHBkmFpAOd07vceWWE+av1j6OmYcaTlFHaUcsYsYG6mV+fG+J6rsdnnhMCvP6rmgg/dY7qgBlxvJrU98jy+FQPwZe11LUO79aacTivEHEYE1IgweVjuz7W8VZjX6/55lJZGUK2/aTcyOJPyhsRAGmuefz39yC24XTmq/sfApTLl4zpAcGZ3gSPjKAJdM+ix/h1J5MIpFs1S+gr4= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000009, 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 22.04.24 16:23, Matthew Wilcox wrote: > I have a fairly radical idea for a new slab allocator design which > I want to sit down with Vlastimil and a whiteboard to flesh out. > Obviously the two of us could just sneak off somewhere, but it'd > probably make more sense to schedule this as a BOF. > > The basic idea is to decouple the objects from the page they reside in. > Instead of having a struct slab to organise the objects on this page, > we organise the objects into sheaves. A sheaf always contains objects > from the same NUMA node, but not necessarily the same page. For each > kmem_cache, there is a per-NUMA-node barn which the per-CPU front end of > the slab allocator will request full sheaves from and give full sheaves > back to. If we RCU-free an object, that goes to the per-CPU rcu-freeing > sheaf, which is handed to RCU once full. > > The obvious objection to all of this is that the story for reclaiming > pages from slab is pretty awful. I'd hope to brainstorm some idea for > improving that (perhaps in the construction of the barn where we could > pull sheaves part and put them back together in some kind of order?) Just as a side note, I would be interested into something that can easily reclaim pages from slab in a specific physical memory area. Target use cases are around alloc_contig_range(), memory offlining an similar. ... but IIUC, the barn/sheep approach wouldn't make that any easier, right? -- Cheers, David / dhildenb