From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 151EA20ADCD for ; Fri, 11 Oct 2024 11:30:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728646224; cv=none; b=WvBOi+Nb6CVNtqktVEO9cshmR5wA/zSIg8aJ8AR/1i1cYA+imB1ql+u0swP+TKlqA8t59PAZsxNvHfc1iPWoxWDMZDNenD7uJpztb2j9XpQrb9NGhFWvQHszaE82+/zNWqEdJklMKSuITVd+CV1FHZLCnCWIJKAlDMkCcsNciIM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728646224; c=relaxed/simple; bh=KbNCL5ELhRX1DBLOQ4LYy3YQJSShcmMhcgPla8EO/R0=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=MkPuU7B8Qc5QNcA+2DHSd8LmAMvMn/CkJrjKzOnI/SElvevMezglUC4CG1yJSvMwL8R/KwlcSvMi+2q+GABXMPZbrTkEexC2nekM15YLD8LIQ84GXAyEE63byiWPNnctCZPIBOd5LvaxQNl3jj6ZBtfod15/RoSPOLyKR6ATcJc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=QTDgphnF; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="QTDgphnF" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1728646222; 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=BgKnAlVvdNa7M1TVTP4imnkAUOe3KVZfS9gpRHqyrkU=; b=QTDgphnFVpkjAKLBAXvaWuDPKHNNn1Uh1B2rraYwwrlFTIr5tyc7Dib5wjBElK6F7FP9BA 2+66zjaOWnM8kQO4ufQct4cHS758cH0vyH44JmPaifuU3OOs19Ld7obKRYLpOTBTYbAWjM cmQA0huKtpGUgo/o5HcIUUYMCbZcbCE= Received: from mail-wm1-f70.google.com (mail-wm1-f70.google.com [209.85.128.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-613-cdos8TWCOZau7p5D9g4S-g-1; Fri, 11 Oct 2024 07:30:18 -0400 X-MC-Unique: cdos8TWCOZau7p5D9g4S-g-1 Received: by mail-wm1-f70.google.com with SMTP id 5b1f17b1804b1-43112243946so16434325e9.3 for ; Fri, 11 Oct 2024 04:30:18 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1728646218; x=1729251018; 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=BgKnAlVvdNa7M1TVTP4imnkAUOe3KVZfS9gpRHqyrkU=; b=ibN7cgp4NwqYCR5Ir50crWXDzliF8XqJe6JA00+zOHJiVL/sed0NRNIZlCyP6MWMqV 6Mf32lpMcgC3WIWSJFgd366+HXZ2UDzD5w8sowa/wm0Bta1EJhYNmEdj+bcpbnWCsro+ 5xQ/+jGUxdo6+o/I8iER87FL6/kq+SWav5odX9QLSP1k3HSU7+hSpgf46kXaf5uBVg66 aJVyo2jNW+04Ls7AX1ItGkYVtr0moS2YN1/FIUUdBWOra8lC3QT5rtJi3+M362lWYz/d 65KvJLB5J6PTEKYXFsIfllus++86cHdbdLYRuOR8YJhCCMTe/f8mVZhzwjazqDIh2Ata FZdQ== X-Forwarded-Encrypted: i=1; AJvYcCX+VJ2AYp6slIKOWvBdOTAIxyUKpZw52l3KQ1W8FoLYzSnh7r3LUZKQXhMB/T28H/02lyAkxjSkA94=@vger.kernel.org X-Gm-Message-State: AOJu0YwkymmO6ocFSKTe4hxDGVRqJA/rVJGtTndo3LdtMogocBWGXVf+ g9jPn/Y/xvvlu1kmS84FTLlFI9zyQCVtsoXdxbGRcZGj2rRa+cJMBW/fz8j77oBsPK/A7mqBpc2 0I9gEItsBDVfQ8pwVvddfp2Wv6BswCopw7Zki+151wZxqr9fQn1DnHp2Iqw== X-Received: by 2002:a05:600c:1d1d:b0:42c:b62c:9f0d with SMTP id 5b1f17b1804b1-4311ded8d67mr25345185e9.17.1728646217636; Fri, 11 Oct 2024 04:30:17 -0700 (PDT) X-Google-Smtp-Source: AGHT+IH0dcHaxSSkqrKIfOhzxYdvusYTaDE+z4Ie92vdynPfeuOB8qYp+KKXeZTarxOBtSPl59dHIA== X-Received: by 2002:a05:600c:1d1d:b0:42c:b62c:9f0d with SMTP id 5b1f17b1804b1-4311ded8d67mr25344915e9.17.1728646217281; Fri, 11 Oct 2024 04:30:17 -0700 (PDT) Received: from ?IPV6:2003:cb:c749:9100:c078:eec6:f2f4:dd3b? (p200300cbc7499100c078eec6f2f4dd3b.dip0.t-ipconnect.de. [2003:cb:c749:9100:c078:eec6:f2f4:dd3b]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-430ccf51942sm71657285e9.27.2024.10.11.04.30.16 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 11 Oct 2024 04:30:16 -0700 (PDT) Message-ID: <12c0a19e-784d-4ac0-8d3c-d5242bcd3723@redhat.com> Date: Fri, 11 Oct 2024 13:30:15 +0200 Precedence: bulk X-Mailing-List: linux-cxl@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC] resource: Avoid unnecessary resource tree walking in __region_intersects() To: Andy Shevchenko Cc: "Huang, Ying" , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-cxl@vger.kernel.org, Dan Williams , Davidlohr Bueso , Jonathan Cameron , Alistair Popple , Bjorn Helgaas , Baoquan He , Dave Jiang , Alison Schofield References: <20241010065558.1347018-1-ying.huang@intel.com> <87set3a1nm.fsf@yhuang6-desk2.ccr.corp.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: 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 On 11.10.24 13:19, Andy Shevchenko wrote: > On Fri, Oct 11, 2024 at 02:15:55PM +0300, Andy Shevchenko wrote: >> On Fri, Oct 11, 2024 at 12:51:09PM +0200, David Hildenbrand wrote: >>> On 11.10.24 12:49, Andy Shevchenko wrote: >>>> On Fri, Oct 11, 2024 at 09:06:37AM +0800, Huang, Ying wrote: >>>>> David Hildenbrand writes: >>>>>> On 10.10.24 08:55, Huang Ying wrote: > > ... > >>>>>> for ((_p) = (_root)->child; (_p); (_p) = next_resource_XXX(_root, _p)) >>>>> >>>>> Yes. This can improve code readability. >>>>> >>>>> A possible issue is that "_root" will be evaluated twice in above macro >>>>> definition. IMO, this should be avoided. >>>> >>>> Ideally, yes. But how many for_each type of macros you see that really try hard >>>> to achieve that? I believe we shouldn't worry right now about this and rely on >>>> the fact that root is the given variable. Or do you have an example of what you >>>> suggested in the other reply, i.e. where it's an evaluation of the heavy call? >>>> >>>>> Do you have some idea about >>>>> how to do that? Something like below? >>>>> >>>>> #define for_each_resource_XXX(_root, _p) \ >>>>> for (typeof(_root) __root = (_root), __p = (_p) = (__root)->child; \ >>>>> __p && (_p); (_p) = next_resource_XXX(__root, _p)) >>>> >>>> This is a bit ugly :-( I would avoid ugliness as long as we have no problem to >>>> solve (see above). >>> >>> Fully agreed, I didn't quite understand the concern about "evaluation" at >>> first. >> >> It's a basic concept for macros and a good mine field even for the simple >> cases. >> >>> If it's just reading a variable twice, it doesn't matter at all right >>> now. >> >> The problem (even if it's a variable) is that the content of variable can be >> changed when run in non-atomic context, i.e. two evaluations will give two >> different results. Most "simple" for_each macros leave this exercise to the >> caller. That's what I also suggest for now. > > For any context as Ying provided an example with calls, they have to be > idempotent, or you definitely get two different pointers for these, which is > bigger issue that what I described above. Ah, now I understood what Ying meant: if the root pointer is modified within the loop body we'd be in trouble. -- Cheers, David / dhildenb