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Thu, 31 Jul 2025 18:41:15 +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 RvK0Gcu4i2hhSgAAD6G6ig (envelope-from ); Thu, 31 Jul 2025 18:41:15 +0000 Message-ID: <71df781c-3ef3-4b26-9ba8-93fc7d4f9eec@suse.cz> Date: Thu, 31 Jul 2025 20:41:14 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: Realtime threads delayed due to kcompactd0 Content-Language: en-US To: Frank van der Linden , Alexander Krabler Cc: "linux-rt-users@vger.kernel.org" , "linux-mm@kvack.org" , Dennis Schimmel , Daniel Braunwarth References: 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-Queue-Id: 34955C000D X-Rspam-User: X-Rspamd-Server: rspam09 X-Stat-Signature: imsspg9j9ndxh6tdwyr4s9cf6tbmndyc X-HE-Tag: 1753987276-994871 X-HE-Meta: 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 xfnBDQNa ES+OS1uwQN1MhceLDE48A317glIYQjAlIYsAtXb2jc/2X1iRfRgDseY7yRrHPiAUJGbgu3G3AxKxmaKX9jDtv70VRWe2zR2rzv0KIz8EOX/pKbvFsycHjWziTa7A8BlVptfhqWivr0Tat8yFe698RAy0nCaaVIzXtmpYNSKhMABYHUVVvT+0EtXXCTAcIABI69CiF2OXNAVkCdbOffWLAeQWDGomi4626Vr7EOswRdWE1wl6FXNWAPv3gZpMgO2OYpEtpp0AAG18+i7cqTLz6Lp6pJr+11jfj0TGUeDdKcnxM2noD68qJH5L6Ml4ZOeAIEVA/ 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 7/31/25 20:34, Frank van der Linden wrote: > Not sure what the right thing to do would be. Either explicitly boost > the priority of a thread temporarily during migrate_pages_batch, or > mitigate the issue by dealing with 'busy' pages more quickly in > migrate_pages_batch. There's a workaround for realtime tasks. If you mlock[all]() their memory, setting sysctl vm.compact_unevictable_allowed to 0 should exclude these pages from migration by compaction. Vlastimil > - Frank >