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 E0F97EEB3 for ; Thu, 1 Aug 2024 09:36:20 +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=1722504982; cv=none; b=unTIJXwEVru2D0xCkuPRyqTnr7YdZmICDcEzOpkT+Brk/Uat/y6qYCi+43znr+ICmRff1Y7vmCMn5+kDE3YplOItV/cO3swJ3XUqP6p0AlWc2gcAWQXSSw8hgRYjKelrLjJh5zxe/1F1akb1/RUsCq8/lgp7ae0m0WvxxBRHWjY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722504982; c=relaxed/simple; bh=RQAbB+4xwgd8rgrT5Xo97jqhsVqqGwZd4S+HhvCqU10=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=UgFTMKFWRFF/oA61ia26gaHJDITgczDlDC3fiwyXFVWX/bvUeGXirGmEAZS7QedyOn6XoBajexYeNFtErWIdk1gP5P9xVWtUd8hUc6vfEOZQaNOjf4oTd9eBm9el+y6g6vja39FMDLDp7RbHPy8kV8RspNLG9bdqPpbwmXR2u78= 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=WRSdpF5n; 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="WRSdpF5n" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1722504980; 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=KJ/HMyeCTpAdrNibsjz2nmyKmky95K7l5NS86QU5jXI=; b=WRSdpF5nIlH3YQJR5Pax8xPkCgS67DZr2oAvxXFlc9hA2+N/GtgrsMB9BwtLhUIMkaGEIe mi11qs8253xusQGcFDtSMrbvImiWJgrvaFlxEOY5kEuePQKaiEDju8yrU1p1cmDY+hTbSy NKkuRXx+/OTSZlixwgHSTvN/t3jCEC4= Received: from mail-lf1-f71.google.com (mail-lf1-f71.google.com [209.85.167.71]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-299-dC-ZZY70MoyG0JGFL26Frg-1; Thu, 01 Aug 2024 05:36:18 -0400 X-MC-Unique: dC-ZZY70MoyG0JGFL26Frg-1 Received: by mail-lf1-f71.google.com with SMTP id 2adb3069b0e04-52efcb739adso1164625e87.2 for ; Thu, 01 Aug 2024 02:36:18 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1722504977; x=1723109777; h=content-transfer-encoding:in-reply-to:organization:autocrypt :content-language:from: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=KJ/HMyeCTpAdrNibsjz2nmyKmky95K7l5NS86QU5jXI=; b=X03X+Z9uYHSbNNNZWB37ggRAXYWQTcLfdDMuwJdPpAaVRlwxTufoFqvC6lDMrq6ye6 AEvqnDmJk75KpVmBbg3+3l/2ZMUDG1cFY0Pa27X3uS08YNoiu4ZEUhz34YEyb7m+oSG8 6pfH9j1PfsSO4lut7JPETOvA9/tkvhg70P79hRbWQtXt66YXwbWEwTOw4mvBIccswecv fRV7TqLcyoi+3YYroDdXYZFQ85fe+DBwwegRuwDOj4l1ZR4ShnH0tjCDGta3u6WYX+1S uD7sR+/vFOQgaUNjgYkV3ll1Vl6iRx6tRkOX2JL/LtAakia8qi1xLZ0F/8vp35scKCGv iuXQ== X-Forwarded-Encrypted: i=1; AJvYcCXGEVz4fEPiMlz1mZak5i1iuWZR4vH1CQhohnpxbaW16Lywv9RPl7oJXh7lUspTkGLbGiEz+ljuDL/INwkj1xy5x2SZ1++NsbeQHsmb X-Gm-Message-State: AOJu0Yz0B7U3kvS3jTrz3D+6GxyzEjP5n9GTJRIe/+aIeQFFMwIv3+t1 RbdKrIzl+ondBf+hY3Q0o0gVpVdeCNCkgowNWMigMDV3Ipn25fai+xuzKa7MgFd9l2ue9bZbL1w tr+blU1mJgw81+qatOdlys73CW5mS2RvH8DJq7+nF/1xqJIlWIIS3NPS0tnpbsA== X-Received: by 2002:ac2:46ef:0:b0:530:ae0a:ab7a with SMTP id 2adb3069b0e04-530b61aa918mr892620e87.17.1722504977094; Thu, 01 Aug 2024 02:36:17 -0700 (PDT) X-Google-Smtp-Source: AGHT+IFBu+QMo4gAEWvVK7f3J31mT8lTsS1wPjplRZ9rVb/L5dLtT7Zpo/p40oBB0gNZnxzN3H/cdw== X-Received: by 2002:ac2:46ef:0:b0:530:ae0a:ab7a with SMTP id 2adb3069b0e04-530b61aa918mr892597e87.17.1722504976510; Thu, 01 Aug 2024 02:36:16 -0700 (PDT) Received: from ?IPV6:2003:cb:c707:5c00:e650:bcd7:e2a0:54fe? (p200300cbc7075c00e650bcd7e2a054fe.dip0.t-ipconnect.de. [2003:cb:c707:5c00:e650:bcd7:e2a0:54fe]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4282baccccfsm50752385e9.29.2024.08.01.02.36.14 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 01 Aug 2024 02:36:16 -0700 (PDT) Message-ID: <37ae59f2-777a-4a58-ae58-4a20066364dd@redhat.com> Date: Thu, 1 Aug 2024 11:36:14 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v6 05/11] mm: Add fast_only bool to test_young and clear_young MMU notifiers To: James Houghton , Andrew Morton , Paolo Bonzini Cc: Ankit Agrawal , Axel Rasmussen , Catalin Marinas , David Matlack , David Rientjes , James Morse , Jason Gunthorpe , Jonathan Corbet , Marc Zyngier , Oliver Upton , Raghavendra Rao Ananta , Ryan Roberts , Sean Christopherson , Shaoqin Huang , Suzuki K Poulose , Wei Xu , Will Deacon , Yu Zhao , Zenghui Yu , kvmarm@lists.linux.dev, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org References: <20240724011037.3671523-1-jthoughton@google.com> <20240724011037.3671523-6-jthoughton@google.com> From: David Hildenbrand Content-Language: en-US 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: <20240724011037.3671523-6-jthoughton@google.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 24.07.24 03:10, James Houghton wrote: > For implementers, the fast_only bool indicates that the age information > needs to be harvested such that we do not slow down other MMU operations, > and ideally that we are not ourselves slowed down by other MMU > operations. Usually this means that the implementation should be > lockless. But what are the semantics if "fast_only" cannot be achieved by the implementer? Can we add some documentation to the new functions that explain what this mysterious "fast_only" is and what the expected semantics are? Please? :) -- Cheers, David / dhildenb