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Tue, 20 Jan 2026 10:32:57 +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 yYFUKNlZb2kdbwAAD6G6ig (envelope-from ); Tue, 20 Jan 2026 10:32:57 +0000 Message-ID: <1390b9ce-0ed1-4cc9-845f-fa4dd5f3ffc8@suse.cz> Date: Tue, 20 Jan 2026 11:32:57 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 09/21] slab: add optimized sheaf refill from partial list Content-Language: en-US To: Harry Yoo Cc: Petr Tesarik , Christoph Lameter , David Rientjes , Roman Gushchin , Hao Li , 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 References: <20260116-sheaves-for-all-v3-0-5595cb000772@suse.cz> <20260116-sheaves-for-all-v3-9-5595cb000772@suse.cz> <2232564a-b3f7-4591-abe2-8f1711590e6e@suse.cz> 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: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Action: no action X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 68F9440009 X-Rspam-User: X-Stat-Signature: ishqa6rbedsu69t6ag36ztbdaio6nr8k X-HE-Tag: 1768905179-638579 X-HE-Meta: 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 VkkpSTnS 4T6ttc8ujWTTlzXWii51mtDBq2IclEw3hPvoDmyuH68Ek3sYDGQWe4YheiSeFw8Nhcoir6AEgEV4RYxZjHDZqIQS/S4zctWYpNnK0l3CiGZ7b9kplXX7hCVntEsllHJRYS4EMwMkpoHyFVQu+XWJKBJrRcgL8hIil4vwtvyGDBGgzpIOSEV9BlfioOepaKuQEx4tXE2n/kTphZTSbKvVGwX6ZASSCV4fk1uD/19zISa33uMbK/G0nxPhHg4pmlqL8Fyh6kLn2LomuGwWERGeqB0lHxAUGaoq0W+As 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 11:27, Harry Yoo wrote: > On Tue, Jan 20, 2026 at 07:33:47AM +0100, Vlastimil Babka wrote: >> >> Right, so the plan was to set min to some fraction of max when refilling >> sheaves, with the goal of maximizing the chance that once we grab a slab >> from the partial list, we almost certainly fully use it and don't have to >> return it back. > > Oh, you had a plan! > > I'm having trouble imagining what it would look like though. > If we fetch more objects than `to_fill`, where do they go? > Have a larger array and fill multiple sheaves with it? Ah that wouldn't happen. Rather we would consider sheaf to be full even if it was filled a bit below its capacity, if trying to reach the full capacity would mean taking a slab from partial list, not using all objects from it and having to return it to the list. Of course this would not apply for a prefilled sheaf request or kmem_cache_alloc_bulk(). >> But I didn't get to there yet. It seems worthwile to try >> though so we can leave the implementation prepared for it? > > Yeah that's fine. >