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Mon, 29 Sep 2025 07:39:57 +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 LYSyHc032mhaIQAAD6G6ig (envelope-from ); Mon, 29 Sep 2025 07:39:57 +0000 Message-ID: <6b983596-e521-4714-8a5b-758da76eb1c7@suse.cz> Date: Mon, 29 Sep 2025 09:39:57 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v8 22/23] maple_tree: Add single node allocation support to maple state Content-Language: en-US To: Suren Baghdasaryan Cc: "Liam R. Howlett" , Christoph Lameter , David Rientjes , 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 References: <20250910-slub-percpu-caches-v8-0-ca3099d8352c@suse.cz> <20250910-slub-percpu-caches-v8-22-ca3099d8352c@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: 8bit X-Stat-Signature: uctic5arx6hy3ta81f4bw33crutt3j31 X-Rspam-User: X-Rspamd-Queue-Id: B55971C000B X-Rspamd-Server: rspam10 X-HE-Tag: 1759131599-416591 X-HE-Meta: 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 lwkDfkCv 6A094jFgekQ9Rdcti+NfNsxByX8LUHrib77FtP3cMWoNZE7rYFdXmqdWwXcrilLK6VSIUUzh3drw6L2x+Jp+lyyH9H6cdYj7/iU3TKVfElrl3p/aXtr6nIuuaSyv2ESD99xgPHjy6BGYac1RemE4BGJRj6SIlXYmAMshUIoIEPaZ1vWyShKIfnVwG2g2+R6I4IwYYLoc+6yEqeLDqLgp1xXRrJPiyurEJzuVyoWRFzZ2FGBJiUYgVx4C99rhv0Tn0HIv1u/MylJz9NMsf9a6hBRQc7sUB8I/TUR6SZN1F5TKTtpS5eVfStFJUtZMQYW4q4BAFC79t4gqf+rVTqgX6jukevOzFrErzAv2OkOrqxzs/fwY1LS7KrbvCpF0m/eZVhhoC 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 9/27/25 03:17, Suren Baghdasaryan wrote: > On Wed, Sep 10, 2025 at 1:01 AM Vlastimil Babka wrote: >> >> From: "Liam R. Howlett" >> >> The fast path through a write will require replacing a single node in >> the tree. Using a sheaf (32 nodes) is too heavy for the fast path, so >> special case the node store operation by just allocating one node in the >> maple state. >> >> Signed-off-by: Liam R. Howlett >> Signed-off-by: Vlastimil Babka >> --- >> include/linux/maple_tree.h | 4 +++- >> lib/maple_tree.c | 47 +++++++++++++++++++++++++++++++++++----- >> tools/testing/radix-tree/maple.c | 9 ++++++-- >> 3 files changed, 51 insertions(+), 9 deletions(-) >> >> diff --git a/include/linux/maple_tree.h b/include/linux/maple_tree.h >> index 166fd67e00d882b1e6de1f80c1b590bba7497cd3..562a1e9e5132b5b1fa8f8402a7cadd8abb65e323 100644 >> --- a/include/linux/maple_tree.h >> +++ b/include/linux/maple_tree.h >> @@ -443,6 +443,7 @@ struct ma_state { >> unsigned long min; /* The minimum index of this node - implied pivot min */ >> unsigned long max; /* The maximum index of this node - implied pivot max */ >> struct slab_sheaf *sheaf; /* Allocated nodes for this operation */ >> + struct maple_node *alloc; /* allocated nodes */ Replacing with: /* A single allocated node for fast path writes */ since I'm touching it anyway due to previous patch fixup. >> >> @@ -1093,9 +1100,34 @@ static inline struct maple_node *mas_pop_node(struct ma_state *mas) >> */ >> static inline void mas_alloc_nodes(struct ma_state *mas, gfp_t gfp) >> { >> - if (unlikely(mas->sheaf)) { >> - unsigned long refill = mas->node_request; >> + if (!mas->node_request) >> + return; >> + >> + if (mas->node_request == 1) { >> + if (mas->sheaf) >> + goto use_sheaf; > > Hmm, I don't get the above logic. One node is requested and instead of > using possibly available mas->alloc, we jump to using mas->sheaf and > freeing mas->alloc... That does not sound efficient. What am I > missing? I'm not changing it now due to merge window, only cosmetic changes and r-b tags. Can leave it to a follow-up optimization.