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Tue, 27 Jan 2026 17:01:57 +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 9FaSJoXveGmdWQAAD6G6ig (envelope-from ); Tue, 27 Jan 2026 17:01:57 +0000 Message-ID: Date: Tue, 27 Jan 2026 18:01:57 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 06/22] slab: add sheaves to most caches Content-Language: en-US To: "Liam R. Howlett" , Harry Yoo , Petr Tesarik , Christoph Lameter , David Rientjes , Roman Gushchin , Hao Li , Andrew Morton , Uladzislau Rezki , 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: <20260123-sheaves-for-all-v4-0-041323d506f7@suse.cz> <20260123-sheaves-for-all-v4-6-041323d506f7@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-Rspam-User: X-Rspamd-Queue-Id: 72B4440005 X-Rspamd-Server: rspam07 X-Stat-Signature: a3md586mkqpsb4gc7hhmjsfqs7yk7t49 X-HE-Tag: 1769533319-802968 X-HE-Meta: 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 DbcRvB3d fWTx1eji2xrfoDWsmXVZqLq5r16VNBOHM9+aKe1Swl1f84ERdRNTP16Q4wZN0A0twpbHU8t2qCHYDMJTVb8M0Pm0t5S0TFQ0VxwTQfSrS+HUWPMYOtvZvg/0t35qrnxVpNo6zz4zZW4VV3jJ3ciaixb9oGzXYVA907TFcLz9ZpCtf9m8ryanHOGVc0iw6klNZxvxxZOg6GesN50egSYEHUi6wI82KVKfRtvyTY5dNRjaR8Z2MpTaKpN4F22ZIAlUudwPdO7TTF7nDYL3dQnvbgGIRhBhXDzL1nrdLOiaBZ7FLJ4933tCn/EAKQhC2UGb/QyI1hOD7fu91xlIJKi8ssGiaCg== 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 1/27/26 17:34, Liam R. Howlett wrote: > * Vlastimil Babka [260123 01:53]: >> In the first step to replace cpu (partial) slabs with sheaves, enable >> sheaves for almost all caches. Treat args->sheaf_capacity as a minimum, >> and calculate sheaf capacity with a formula that roughly follows the >> formula for number of objects in cpu partial slabs in set_cpu_partial(). >> >> This should achieve roughly similar contention on the barn spin lock as >> there's currently for node list_lock without sheaves, to make >> benchmarking results comparable. It can be further tuned later. >> >> Don't enable sheaves for bootstrap caches as that wouldn't work. In >> order to recognize them by SLAB_NO_OBJ_EXT, make sure the flag exists >> even for !CONFIG_SLAB_OBJ_EXT. >> >> This limitation will be lifted for kmalloc caches after the necessary >> bootstrapping changes. >> >> Also do not enable sheaves for SLAB_NOLEAKTRACE caches to avoid >> recursion with kmemleak tracking (thanks to Breno Leitao). >> >> Reviewed-by: Suren Baghdasaryan >> Reviewed-by: Harry Yoo >> Signed-off-by: Vlastimil Babka > > Is there a way to force a specific limit to the sheaf capacity if you > want a lower number than what is calculated in > calculate_sheaf_capacity()? No. > That is, it seems your code always decides > if the specified sheaf number is smaller right now. That's right. It shouldn't break anything, AFAICS. > I'm not sure it's > practical to want a smaller number though. Yeah I found no such reason, so until we stumble upon one, we don't need such support I think? > Reviewed-by: Liam R. Howlett Thanks!