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Fri, 6 Feb 2026 16:44:45 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id Itz5Gn0ahmnxVgAAD6G6ig (envelope-from ); Fri, 06 Feb 2026 16:44:45 +0000 Message-ID: <699982e5-6660-4e48-be57-3ee7326a20d5@suse.cz> Date: Fri, 6 Feb 2026 17:44:45 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 00/22] slab: replace cpu (partial) slabs with sheaves Content-Language: en-US To: "Christoph Lameter (Ampere)" Cc: Hao Li , Harry Yoo , Petr Tesarik , David Rientjes , Roman Gushchin , Andrew Morton , Uladzislau Rezki , "Liam R. Howlett" , Suren Baghdasaryan , Sebastian Andrzej Siewior , Alexei Starovoitov , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-rt-devel@lists.linux.dev, bpf@vger.kernel.org, kasan-dev@googlegroups.com, kernel test robot , stable@vger.kernel.org, "Paul E. McKenney" References: <20260123-sheaves-for-all-v4-0-041323d506f7@suse.cz> <390d6318-08f3-403b-bf96-4675a0d1fe98@suse.cz> <665ff739-73d8-4996-95e0-f09c3e5b6552@suse.cz> <2abde505-1e35-8d74-2806-7a3cd430e306@gentwo.org> From: Vlastimil Babka Autocrypt: addr=vbabka@suse.cz; keydata= xsFNBFZdmxYBEADsw/SiUSjB0dM+vSh95UkgcHjzEVBlby/Fg+g42O7LAEkCYXi/vvq31JTB KxRWDHX0R2tgpFDXHnzZcQywawu8eSq0LxzxFNYMvtB7sV1pxYwej2qx9B75qW2plBs+7+YB 87tMFA+u+L4Z5xAzIimfLD5EKC56kJ1CsXlM8S/LHcmdD9Ctkn3trYDNnat0eoAcfPIP2OZ+ 9oe9IF/R28zmh0ifLXyJQQz5ofdj4bPf8ecEW0rhcqHfTD8k4yK0xxt3xW+6Exqp9n9bydiy tcSAw/TahjW6yrA+6JhSBv1v2tIm+itQc073zjSX8OFL51qQVzRFr7H2UQG33lw2QrvHRXqD Ot7ViKam7v0Ho9wEWiQOOZlHItOOXFphWb2yq3nzrKe45oWoSgkxKb97MVsQ+q2SYjJRBBH4 8qKhphADYxkIP6yut/eaj9ImvRUZZRi0DTc8xfnvHGTjKbJzC2xpFcY0DQbZzuwsIZ8OPJCc LM4S7mT25NE5kUTG/TKQCk922vRdGVMoLA7dIQrgXnRXtyT61sg8PG4wcfOnuWf8577aXP1x 6mzw3/jh3F+oSBHb/GcLC7mvWreJifUL2gEdssGfXhGWBo6zLS3qhgtwjay0Jl+kza1lo+Cv BB2T79D4WGdDuVa4eOrQ02TxqGN7G0Biz5ZLRSFzQSQwLn8fbwARAQABzSBWbGFzdGltaWwg QmFia2EgPHZiYWJrYUBzdXNlLmN6PsLBlAQTAQoAPgIbAwULCQgHAwUVCgkICwUWAgMBAAIe AQIXgBYhBKlA1DSZLC6OmRA9UCJPp+fMgqZkBQJnyBr8BQka0IFQAAoJECJPp+fMgqZkqmMQ AIbGN95ptUMUvo6aAdhxaOCHXp1DfIBuIOK/zpx8ylY4pOwu3GRe4dQ8u4XS9gaZ96Gj4bC+ jwWcSmn+TjtKW3rH1dRKopvC07tSJIGGVyw7ieV/5cbFffA8NL0ILowzVg8w1ipnz1VTkWDr 2zcfslxJsJ6vhXw5/npcY0ldeC1E8f6UUoa4eyoskd70vO0wOAoGd02ZkJoox3F5ODM0kjHu Y97VLOa3GG66lh+ZEelVZEujHfKceCw9G3PMvEzyLFbXvSOigZQMdKzQ8D/OChwqig8wFBmV QCPS4yDdmZP3oeDHRjJ9jvMUKoYODiNKsl2F+xXwyRM2qoKRqFlhCn4usVd1+wmv9iLV8nPs 2Db1ZIa49fJet3Sk3PN4bV1rAPuWvtbuTBN39Q/6MgkLTYHb84HyFKw14Rqe5YorrBLbF3rl M51Dpf6Egu1yTJDHCTEwePWug4XI11FT8lK0LNnHNpbhTCYRjX73iWOnFraJNcURld1jL1nV r/LRD+/e2gNtSTPK0Qkon6HcOBZnxRoqtazTU6YQRmGlT0v+rukj/cn5sToYibWLn+RoV1CE Qj6tApOiHBkpEsCzHGu+iDQ1WT0Idtdynst738f/uCeCMkdRu4WMZjteQaqvARFwCy3P/jpK uvzMtves5HvZw33ZwOtMCgbpce00DaET4y/UzsBNBFsZNTUBCACfQfpSsWJZyi+SHoRdVyX5 J6rI7okc4+b571a7RXD5UhS9dlVRVVAtrU9ANSLqPTQKGVxHrqD39XSw8hxK61pw8p90pg4G /N3iuWEvyt+t0SxDDkClnGsDyRhlUyEWYFEoBrrCizbmahOUwqkJbNMfzj5Y7n7OIJOxNRkB IBOjPdF26dMP69BwePQao1M8Acrrex9sAHYjQGyVmReRjVEtv9iG4DoTsnIR3amKVk6si4Ea X/mrapJqSCcBUVYUFH8M7bsm4CSxier5ofy8jTEa/CfvkqpKThTMCQPNZKY7hke5qEq1CBk2 wxhX48ZrJEFf1v3NuV3OimgsF2odzieNABEBAAHCwXwEGAEKACYCGwwWIQSpQNQ0mSwujpkQ PVAiT6fnzIKmZAUCZ8gcVAUJFhTonwAKCRAiT6fnzIKmZLY8D/9uo3Ut9yi2YCuASWxr7QQZ lJCViArjymbxYB5NdOeC50/0gnhK4pgdHlE2MdwF6o34x7TPFGpjNFvycZqccSQPJ/gibwNA zx3q9vJT4Vw+YbiyS53iSBLXMweeVV1Jd9IjAoL+EqB0cbxoFXvnjkvP1foiiF5r73jCd4PR rD+GoX5BZ7AZmFYmuJYBm28STM2NA6LhT0X+2su16f/HtummENKcMwom0hNu3MBNPUOrujtW khQrWcJNAAsy4yMoJ2Lw51T/5X5Hc7jQ9da9fyqu+phqlVtn70qpPvgWy4HRhr25fCAEXZDp xG4RNmTm+pqorHOqhBkI7wA7P/nyPo7ZEc3L+ZkQ37u0nlOyrjbNUniPGxPxv1imVq8IyycG AN5FaFxtiELK22gvudghLJaDiRBhn8/AhXc642/Z/yIpizE2xG4KU4AXzb6C+o7LX/WmmsWP Ly6jamSg6tvrdo4/e87lUedEqCtrp2o1xpn5zongf6cQkaLZKQcBQnPmgHO5OG8+50u88D9I rywqgzTUhHFKKF6/9L/lYtrNcHU8Z6Y4Ju/MLUiNYkmtrGIMnkjKCiRqlRrZE/v5YFHbayRD dJKXobXTtCBYpLJM4ZYRpGZXne/FAtWNe4KbNJJqxMvrTOrnIatPj8NhBVI0RSJRsbilh6TE m6M14QORSWTLRg== In-Reply-To: <2abde505-1e35-8d74-2806-7a3cd430e306@gentwo.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 73D0512000B X-Stat-Signature: yhis8hw1bouw4kj8ixa1nwizc3ufbd8g X-Rspam-User: X-HE-Tag: 1770396288-565107 X-HE-Meta: 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 VdpPYsC/ 1gk3qErLIuIaprYIuQL89l13AUnPBGgiHw3Rl/vXqWxXeHQpOU5Lol67q7cGHGWcTk9h9ulEXbQU+GaE0F/vFGdbKz3NcW2H889gn1n7SPjwvj5BuJxb6hE+nF7D0BtoVsNA1rSyhHoTD+Y3oh3daJVZUktNS10RUhOKeO7TnWgLnAUHwdtg6tm6Xl5cvWhMQTE/NNeaoO0SKKF9XxshR7K3MS4tuQvCU2ZVgTBnN2b91GBH6FPjwIGts9UIOge3No3rNElB8JPxA70OPfwU+2qHRDIq3DyCfCMX5gWKNEmjCqQba+de10g/5dA/VG4w/hVpSvy9HQC714bXZA8ygWhu4XoJQhFDcO2ecZQrxLMHgQph+aJg2jaQ0sw== 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 2/4/26 19:24, Christoph Lameter (Ampere) wrote: > On Wed, 4 Feb 2026, Vlastimil Babka wrote: > >> > So I think the performance of the percpu partial list and the sheaves mechanism >> > is roughly the same, which is consistent with our expectations. >> >> Thanks! > > There are other considerations that usually do not show up well in > benchmark tests. > > The sheaves cannot do the spatial optimizations that cpu partial lists > provide. Fragmentation in slab caches (and therefore the nubmer of > partial slab pages) will increase since > > 1. The objects are not immediately returned to their slab pages but end up > in some queuing structure. > > 2. Available objects from a single slab page are not allocated in sequence > to empty partial pages and remove the page from the partial lists. > > Objects are put into some queue on free and are processed on a FIFO basis. > Objects allocated may come from lots of different slab pages potentially > increasing TLB pressure. IIUC this is what you said before [1] and the cover letter has a link and a summary of it. [1] https://lore.kernel.org/all/f7c33974-e520-387e-9e2f-1e523bfe1545@gentwo.org/