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Thu, 22 Jan 2026 08:42:31 +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 QsbALvficWkRdwAAD6G6ig (envelope-from ); Thu, 22 Jan 2026 08:42:31 +0000 Message-ID: Date: Thu, 22 Jan 2026 09:42:31 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 17/21] slab: refill sheaves from all nodes 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-v3-17-5595cb000772@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-Stat-Signature: 6cpbj7y6mya9msp6j3bjxu6fhe38rta3 X-Rspamd-Queue-Id: ED65E140007 X-Rspam-User: X-Rspamd-Server: rspam04 X-HE-Tag: 1769071353-504448 X-HE-Meta: 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 ZrGklFr+ 1hc+pwSzSnkOwQwNrg0O9YxmlyJsEet1A/sUXN37cB0ZT/OF+7Q8tW4sonktNDjrsQHkPY8DtZxsln6d8n+q8sfbnaj3HfFgbW42qlhNsiGLE+SD1G9Ahfy8nKiEXPMgNMy68zN79s/uywKKj3h/coU0DTEpQne6r7Lyy8Uwq3OC870XWL3JQ6Lhap4Ob/7MZrd72gjbbxAWUKBi+7Yb37l6vzteSPqFIyRRjHMlc9o+ahy2a6nHVc+Lep0jsIm7yuNL3/+NYu8PPfifMivmKDRxxdDbIC5lxzc4gIRymLkyl+gyY7vWHg0QpjA== 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 1/22/26 08:02, Harry Yoo wrote: > On Fri, Jan 16, 2026 at 03:40:37PM +0100, Vlastimil Babka wrote: >> __refill_objects() currently only attempts to get partial slabs from the >> local node and then allocates new slab(s). Expand it to trying also >> other nodes while observing the remote node defrag ratio, similarly to >> get_any_partial(). >> >> This will prevent allocating new slabs on a node while other nodes have >> many free slabs. It does mean sheaves will contain non-local objects in >> that case. Allocations that care about specific node will still be >> served appropriately, but might get a slowpath allocation. > > Hmm one more question. > > Given frees to remote nodes bypass sheaves layer anyway, isn't it > more reasonable to let refill_objects() fail sometimes instead of > allocating new local slabs and fall back to slowpath (based on defrag_ratio)? You mean if we can't refill from local partial list, we give up and perhaps fail alloc_from_pcs()? Then the __slab_alloc_node() fallback would do allocate local slab or try remote nodes? Wouldn't that mean __slab_alloc_node() does all that work for a single object, and slow everything down? Only in case of a new slab it would somehow amortize because the next attempt would refill from it. >> Like get_any_partial() we do observe cpuset_zone_allowed(), although we >> might be refilling a sheaf that will be then used from a different >> allocation context. >> >> We can also use the resulting refill_objects() in >> __kmem_cache_alloc_bulk() for non-debug caches. This means >> kmem_cache_alloc_bulk() will get better performance when sheaves are >> exhausted. kmem_cache_alloc_bulk() cannot indicate a preferred node so >> it's compatible with sheaves refill in preferring the local node. >> Its users also have gfp flags that allow spinning, so document that >> as a requirement. >> >> Reviewed-by: Suren Baghdasaryan >> Signed-off-by: Vlastimil Babka >> --- > >