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Thu, 27 Nov 2025 13:18:03 +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 DeFMCItPKGlyRAAAD6G6ig (envelope-from ); Thu, 27 Nov 2025 13:18:03 +0000 Message-ID: Date: Thu, 27 Nov 2025 14:18:02 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v8 04/23] slab: add sheaf support for batching kfree_rcu() operations Content-Language: en-US To: Jon Hunter , Daniel Gomez , Suren Baghdasaryan , "Liam R. Howlett" , Christoph Lameter , David Rientjes Cc: Roman Gushchin , Harry Yoo , Uladzislau Rezki , Sidhartha Kumar , linux-mm@kvack.org, linux-kernel@vger.kernel.org, rcu@vger.kernel.org, maple-tree@lists.infradead.org, linux-modules@vger.kernel.org, Luis Chamberlain , Petr Pavlu , Sami Tolvanen , Aaron Tomlin , Lucas De Marchi , "linux-tegra@vger.kernel.org" References: <20250910-slub-percpu-caches-v8-0-ca3099d8352c@suse.cz> <20250910-slub-percpu-caches-v8-4-ca3099d8352c@suse.cz> <0406562e-2066-4cf8-9902-b2b0616dd742@kernel.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: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Action: no action X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 90DA240011 X-Stat-Signature: ta1gp3z3tdcx5swapt1k3xm75ye8agmb X-Rspam-User: X-HE-Tag: 1764249485-412822 X-HE-Meta: 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 JZb8H8R2 Ud0SV5WDfpD6YO0vnW+T4agJbwE945X5DcEEnltMP1I93O0YWLSRr1QC4IGfNEhHkAFoVMH6iz1wLbzpq50CBeLToYHxD7zqn33aMyTfB8nnATyhiMg9lHYP587rO4TVctELp8ap26Ni1NQ40RUIz93rqRI9mt13ivxc6xj04PRefNplfuIQh5TE/npzGoKVtjQkvKsBC9t5epEr4XPic+Q9+70DCSy8XyUy2Lkz39Tv0Ha/ETyItzGXdQOP1/gQNNPl791iQeNGLMGlp7h/LyS7mqu68PHhR1FXTJkd3R46R7pNOzZTJkcFqux13A6N0aYqtYenvBfxmlGJNHkZDRWEWTbx5BQ+oLlAOyDdf8lKWxIsQI9v3rn4/yA== 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 11/27/25 12:38, Jon Hunter wrote: > > > On 31/10/2025 21:32, Daniel Gomez wrote: >> >> >> On 10/09/2025 10.01, Vlastimil Babka wrote: >> >> Hi Vlastimil, >> >> This patch increases kmod selftest (stress module loader) runtime by about >> ~50-60%, from ~200s to ~300s total execution time. My tested kernel has >> CONFIG_KVFREE_RCU_BATCHED enabled. Any idea or suggestions on what might be >> causing this, or how to address it? >> > > I have been looking into a regression for Linux v6.18-rc where time > taken to run some internal graphics tests on our Tegra234 device has > increased from around 35% causing the tests to timeout. Bisect is > pointing to this commit and I also see we have CONFIG_KVFREE_RCU_BATCHED=y. Do the tegra tests involve (frequent) module unloads too, then? Or calling kmem_cache_destroy() somewhere? Thanks, Vlastimil > I have not tried disabling CONFIG_KVFREE_RCU_BATCHED=y but I can. I am > not sure if there are any downsides to disabling this? > > Thanks > Jon >