From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id B38ABCF11EC for ; Thu, 10 Oct 2024 12:54:42 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 4E26A6B0085; Thu, 10 Oct 2024 08:54:42 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 492B56B0088; Thu, 10 Oct 2024 08:54:42 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3347A6B0089; Thu, 10 Oct 2024 08:54:42 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 151F66B0085 for ; Thu, 10 Oct 2024 08:54:42 -0400 (EDT) Received: from smtpin29.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id 7662B1401A6 for ; Thu, 10 Oct 2024 12:54:38 +0000 (UTC) X-FDA: 82657686762.29.2C6077C Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by imf26.hostedemail.com (Postfix) with ESMTP id ACE30140016 for ; Thu, 10 Oct 2024 12:54:38 +0000 (UTC) Authentication-Results: imf26.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=Ld7bUSNa; dmarc=pass (policy=none) header.from=redhat.com; spf=pass (imf26.hostedemail.com: domain of david@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=david@redhat.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1728564767; a=rsa-sha256; cv=none; b=Zf2xRJ6aEFuTfihlpGEVz84+8CzcYMGA6A+erbWtv9PweR8iGyF/kglsgSmXerNevPTAEq cNnGG3QumftHmTTbQzmg1uaNEmB0YlDp2tF2OYYq6+fP1lqwOWYNSoZKgmDxZxDhpSlv8r 6WCAFIv1k+PQYw9QkRTr16ZYli3ahgo= ARC-Authentication-Results: i=1; imf26.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=Ld7bUSNa; dmarc=pass (policy=none) header.from=redhat.com; spf=pass (imf26.hostedemail.com: domain of david@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=david@redhat.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1728564767; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=cZL6g0fMpa/mgW56phL714cp05p/JmPmKoNz8gp0+y0=; b=PCMvPWLF/cArnIIjyS8VrtfxNwq8E1YD1+C5Wavqw9BuWf2c7sNpSXrFQO2HxJWOIi/w6r dxEnC+uIA5xHd0CU3uawGYFOIe1JUwyv9JNeit5U+yw0CndCF1ZZEVEEAKHp1ou7YRVOyh 7BYSq/65LdXe8jQeJr4zHfVuP/GxO24= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1728564878; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:autocrypt:autocrypt; bh=cZL6g0fMpa/mgW56phL714cp05p/JmPmKoNz8gp0+y0=; b=Ld7bUSNan79Leea62U2g6KXlZNXa+zFatB7rpXE/aNMPJnpfwYo+EJqukGuQBPdVE2tRkw AeN6UT1UJEJ5uSwUBRzjPcPSUZNQcnNp4TiQSt8FPm80FchLQlC97+3mExdUyG3MiKNi9I mW7F6j2v0UGowKRMn2g3wu32Bkx7unw= Received: from mail-wr1-f72.google.com (mail-wr1-f72.google.com [209.85.221.72]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-426-3yg6WjG8ONakRuBwi5TgBQ-1; Thu, 10 Oct 2024 08:54:37 -0400 X-MC-Unique: 3yg6WjG8ONakRuBwi5TgBQ-1 Received: by mail-wr1-f72.google.com with SMTP id ffacd0b85a97d-37d38a174ecso464874f8f.2 for ; Thu, 10 Oct 2024 05:54:37 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1728564876; x=1729169676; h=content-transfer-encoding:in-reply-to:organization:autocrypt:from :content-language:references:cc:to:subject:user-agent:mime-version :date:message-id:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=cZL6g0fMpa/mgW56phL714cp05p/JmPmKoNz8gp0+y0=; b=QhKWHgvDX8I/0g4nkPvLoK5BkGB+Ol58JfTEg39RDyr0Ltl5wjmqy2r8Pl1IaZ3ZZw sc5YtodImilEzErxy5v9XQ23UERsCHYykPVD2dYQ1VFblj8WcUeBT/8XatVDwqqKnNHG +ixjXSecQ0N9CAskwvX2tmEbl1RUjiFqHooqSkNFh1NFR5FZ2FtbCn5aQJ21dqF4M6ht F8c2yeAjpyvr0qjLWGAtMeWc2ZIPgpnNDh628rq4tTXC/vxi5aZydAhzYXBfY+fRmLyS X12/PbghJD8yZ0mhNs5suFWLYjN4CKZ00EOWSCvS9QhRBpUz9jzQdfjKrlu+enG2B8mk nZ+Q== X-Gm-Message-State: AOJu0Yx5VyecHPSYt4sl2O0tTrXcpP1L4tOBGwOF8OS0jfa4S0tNisTE Jr62tb3sMqLPk0laBw54Nray3bqKmDjDk3QRZzQWV0VgxlkYaNPEzLOLpIt/HdvGQAEra5CD2Zj NyMZz4OLZHe4ufWfJBuQFT+/00dAvHTa0EBn5LyOUUYJlR/UN X-Received: by 2002:a05:600c:3148:b0:42c:a89e:b0e6 with SMTP id 5b1f17b1804b1-431157aa5cbmr32393925e9.11.1728564876364; Thu, 10 Oct 2024 05:54:36 -0700 (PDT) X-Google-Smtp-Source: AGHT+IH2p8L8ELIXrumoPAPLW1IaY8NSi4pHxZ0J4QVILie3z6IAvUH/Ukh/rrSs7O2Sy2/qpzBUWA== X-Received: by 2002:a05:600c:3148:b0:42c:a89e:b0e6 with SMTP id 5b1f17b1804b1-431157aa5cbmr32393715e9.11.1728564875932; Thu, 10 Oct 2024 05:54:35 -0700 (PDT) Received: from ?IPV6:2003:cb:c742:9200:eb2e:74f9:6f5c:3040? (p200300cbc7429200eb2e74f96f5c3040.dip0.t-ipconnect.de. [2003:cb:c742:9200:eb2e:74f9:6f5c:3040]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-430d70b4674sm48380265e9.38.2024.10.10.05.54.34 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 10 Oct 2024 05:54:34 -0700 (PDT) Message-ID: Date: Thu, 10 Oct 2024 14:54:33 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC] resource: Avoid unnecessary resource tree walking in __region_intersects() To: Huang Ying , Andrew Morton Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-cxl@vger.kernel.org, Dan Williams , Davidlohr Bueso , Jonathan Cameron , Alistair Popple , Andy Shevchenko , Bjorn Helgaas , Baoquan He , Dave Jiang , Alison Schofield References: <20241010065558.1347018-1-ying.huang@intel.com> From: David Hildenbrand Autocrypt: addr=david@redhat.com; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzSREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwZgEEwEIAEICGwMGCwkIBwMCBhUIAgkKCwQW AgMBAh4BAheAAhkBFiEEG9nKrXNcTDpGDfzKTd4Q9wD/g1oFAl8Ox4kFCRKpKXgACgkQTd4Q 9wD/g1oHcA//a6Tj7SBNjFNM1iNhWUo1lxAja0lpSodSnB2g4FCZ4R61SBR4l/psBL73xktp rDHrx4aSpwkRP6Epu6mLvhlfjmkRG4OynJ5HG1gfv7RJJfnUdUM1z5kdS8JBrOhMJS2c/gPf wv1TGRq2XdMPnfY2o0CxRqpcLkx4vBODvJGl2mQyJF/gPepdDfcT8/PY9BJ7FL6Hrq1gnAo4 3Iv9qV0JiT2wmZciNyYQhmA1V6dyTRiQ4YAc31zOo2IM+xisPzeSHgw3ONY/XhYvfZ9r7W1l pNQdc2G+o4Di9NPFHQQhDw3YTRR1opJaTlRDzxYxzU6ZnUUBghxt9cwUWTpfCktkMZiPSDGd KgQBjnweV2jw9UOTxjb4LXqDjmSNkjDdQUOU69jGMUXgihvo4zhYcMX8F5gWdRtMR7DzW/YE BgVcyxNkMIXoY1aYj6npHYiNQesQlqjU6azjbH70/SXKM5tNRplgW8TNprMDuntdvV9wNkFs 9TyM02V5aWxFfI42+aivc4KEw69SE9KXwC7FSf5wXzuTot97N9Phj/Z3+jx443jo2NR34XgF 89cct7wJMjOF7bBefo0fPPZQuIma0Zym71cP61OP/i11ahNye6HGKfxGCOcs5wW9kRQEk8P9 M/k2wt3mt/fCQnuP/mWutNPt95w9wSsUyATLmtNrwccz63XOwU0EVcufkQEQAOfX3n0g0fZz Bgm/S2zF/kxQKCEKP8ID+Vz8sy2GpDvveBq4H2Y34XWsT1zLJdvqPI4af4ZSMxuerWjXbVWb T6d4odQIG0fKx4F8NccDqbgHeZRNajXeeJ3R7gAzvWvQNLz4piHrO/B4tf8svmRBL0ZB5P5A 2uhdwLU3NZuK22zpNn4is87BPWF8HhY0L5fafgDMOqnf4guJVJPYNPhUFzXUbPqOKOkL8ojk CXxkOFHAbjstSK5Ca3fKquY3rdX3DNo+EL7FvAiw1mUtS+5GeYE+RMnDCsVFm/C7kY8c2d0G NWkB9pJM5+mnIoFNxy7YBcldYATVeOHoY4LyaUWNnAvFYWp08dHWfZo9WCiJMuTfgtH9tc75 7QanMVdPt6fDK8UUXIBLQ2TWr/sQKE9xtFuEmoQGlE1l6bGaDnnMLcYu+Asp3kDT0w4zYGsx 5r6XQVRH4+5N6eHZiaeYtFOujp5n+pjBaQK7wUUjDilPQ5QMzIuCL4YjVoylWiBNknvQWBXS lQCWmavOT9sttGQXdPCC5ynI+1ymZC1ORZKANLnRAb0NH/UCzcsstw2TAkFnMEbo9Zu9w7Kv AxBQXWeXhJI9XQssfrf4Gusdqx8nPEpfOqCtbbwJMATbHyqLt7/oz/5deGuwxgb65pWIzufa N7eop7uh+6bezi+rugUI+w6DABEBAAHCwXwEGAEIACYCGwwWIQQb2cqtc1xMOkYN/MpN3hD3 AP+DWgUCXw7HsgUJEqkpoQAKCRBN3hD3AP+DWrrpD/4qS3dyVRxDcDHIlmguXjC1Q5tZTwNB boaBTPHSy/Nksu0eY7x6HfQJ3xajVH32Ms6t1trDQmPx2iP5+7iDsb7OKAb5eOS8h+BEBDeq 3ecsQDv0fFJOA9ag5O3LLNk+3x3q7e0uo06XMaY7UHS341ozXUUI7wC7iKfoUTv03iO9El5f XpNMx/YrIMduZ2+nd9Di7o5+KIwlb2mAB9sTNHdMrXesX8eBL6T9b+MZJk+mZuPxKNVfEQMQ a5SxUEADIPQTPNvBewdeI80yeOCrN+Zzwy/Mrx9EPeu59Y5vSJOx/z6OUImD/GhX7Xvkt3kq Er5KTrJz3++B6SH9pum9PuoE/k+nntJkNMmQpR4MCBaV/J9gIOPGodDKnjdng+mXliF3Ptu6 3oxc2RCyGzTlxyMwuc2U5Q7KtUNTdDe8T0uE+9b8BLMVQDDfJjqY0VVqSUwImzTDLX9S4g/8 kC4HRcclk8hpyhY2jKGluZO0awwTIMgVEzmTyBphDg/Gx7dZU1Xf8HFuE+UZ5UDHDTnwgv7E th6RC9+WrhDNspZ9fJjKWRbveQgUFCpe1sa77LAw+XFrKmBHXp9ZVIe90RMe2tRL06BGiRZr jPrnvUsUUsjRoRNJjKKA/REq+sAnhkNPPZ/NNMjaZ5b8Tovi8C0tmxiCHaQYqj7G2rgnT0kt WNyWQQ== Organization: Red Hat In-Reply-To: <20241010065558.1347018-1-ying.huang@intel.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: ACE30140016 X-Stat-Signature: qagnuuqoitc5xfomxetgtwif65jsfs8e X-Rspam-User: X-HE-Tag: 1728564878-165869 X-HE-Meta: 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 1l9tjju+ O5zcZY8t531bPAiYV6R1MZ4Fz+Lvhn9stM4u41MO4zNXlM9A/zyrpOlGSLLWhTMg1syyoK458RoykfsGMVMB+LQp037eUWSqR/CggyzT4rbA3rTEeqdwpCJHVdTCvFchQ+Aqfc2qlGjC1ZC4iRR0VzGxVvfmSnTb7E50+I5xInk7wgwzcK5+8KBicec7qtxsI2JkDzERlN4+frGqzdmRZ52saSoZjQ/3Ovlv42jUQRohtQ5pnHXRf0z+FbCSTOPp8W8TpDUJehBstCj6gV8Jf9/utMsnnmUSvWCQ0kuM/kadhD/Z0CHFSe95UfddngEPjGwMx/JwLkMLE28wydS09Qt9rTZD7lT9i9q+E7aFIF60qblc2/zTkwxuUrPluYJqd4PJXIkcTHO/OYSiWdTGvFbtHWuFcxzuQPG7mi1iJmxl3OaCNGwKKmkjUQ8e6Rnl9QaAf 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 10.10.24 08:55, Huang Ying wrote: > Currently, if __region_intersects() finds any overlapped but unmatched > resource, it walks the descendant resource tree to check for > overlapped and matched descendant resources. This is achieved using > for_each_resource(), which iterates not only the descent tree, but > also subsequent sibling trees in certain scenarios. While this > doesn't introduce bugs, it makes code hard to be understood and > potentially inefficient. > > So, the patch renames next_resource() to __next_resource() and > modified it to return NULL after traversing all descent resources. > Test shows that this avoids unnecessary resource tree walking in > __region_intersects(). > > It appears even better to revise for_each_resource() to traverse the > descendant resource tree of "_root" only. But that will cause "_root" > to be evaluated twice, which I don't find a good way to eliminate. I'm not sure I'm enjoying below code, it makes it harder for me to understand what's happening. I'm also not 100% sure why "p" becomes "root" and "dp" becomes "p" when calling the function :) Likely this works as intended, but it's confusing (IOW, bad naming, especially for dp). I think you should just leave next_resource() alone and rather add a new function that doesn't conditionally consume NULL pointers (and also no skip_children because you're passing false either way). static struct resource *next_resource_XXX(struct resource *root, struct resource *p) { while (!p->sibling && p->parent) { p = p->parent; if (p == root) return NULL; } return p->sibling; } Maybe even better, add a new for_each_resource() macro that expresses the intended semantics. #define for_each_resource_XXX(_root, _p) \ for ((_p) = (_root)->child; (_p); (_p) = next_resource_XXX(_root, _p)) XXX TBD Or do you think this should not only be "improved" for the __region_intersects() use case but for all for_each_resource() users? I cannot tell easily. -- Cheers, David / dhildenb