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 BD645D12686 for ; Tue, 5 Nov 2024 11:09:17 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 3027B6B0098; Tue, 5 Nov 2024 06:09:17 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 2B22D6B0099; Tue, 5 Nov 2024 06:09:17 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 12BB86B009B; Tue, 5 Nov 2024 06:09:17 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id E337A6B0098 for ; Tue, 5 Nov 2024 06:09:16 -0500 (EST) Received: from smtpin18.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id 9D2BCAB310 for ; Tue, 5 Nov 2024 11:09:16 +0000 (UTC) X-FDA: 82751769240.18.964AFD9 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by imf08.hostedemail.com (Postfix) with ESMTP id 5BC69160023 for ; Tue, 5 Nov 2024 11:08:52 +0000 (UTC) Authentication-Results: imf08.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=hjr39F30; dmarc=pass (policy=none) header.from=redhat.com; spf=pass (imf08.hostedemail.com: domain of david@redhat.com designates 170.10.129.124 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=1730804787; 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=4jxkOUZ57nYetmoWY3mq2h4CNdsjkQ08TdFmJGUwEmA=; b=zYSO1FOrW4wgq5x4cdD26IWzslfNU1mtvSMKXzt+ywZb3ZAYK++tLlwEx/gLOMxEQnzkhV ij6NAR05RcAoQOPb8Xk0Ixsfh0OvZnQqQbfRZcLct9bF6KTV5P6KrRyvs2ny+San7EVF2O oChjxFDXMwPZFvCPY5UL9wvuwC6RtXQ= ARC-Authentication-Results: i=1; imf08.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=hjr39F30; dmarc=pass (policy=none) header.from=redhat.com; spf=pass (imf08.hostedemail.com: domain of david@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=david@redhat.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1730804787; a=rsa-sha256; cv=none; b=Yg86S3TripU/uOlWxHw/gDcavMDEhRlcv2A5iWuOGalNvoKfkzWwzq4hBo+bWq1uHN3Rd7 lEIQl7iUj+JVTQ19Mm93O/r72gV3bFN7aRqRtqODsE73ruf7jhIDEgnMkZ76xAxDnhrCSO O1AarP4neGqcAKd9RYmNYb7HQRsOV5Q= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1730804953; 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=4jxkOUZ57nYetmoWY3mq2h4CNdsjkQ08TdFmJGUwEmA=; b=hjr39F30dFsplJIlUCIuCwvXVvXKwLNh5NW/GVbzrVtHtTN3LMlZQfq/34Yw72EkBJJ3/O zUw4wE5iCWj0UB6GVjiBI5dG5YdYUSWI2N79aPwi8KgUGUmBobhGtbMQ4cTEE6lxKyPR7i vVpz0gdV+ePnwwUMlHykyKqvLyqXfqQ= Received: from mail-lf1-f69.google.com (mail-lf1-f69.google.com [209.85.167.69]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-251-xn9O0kKQP_SJuFmmCXiaoQ-1; Tue, 05 Nov 2024 06:09:11 -0500 X-MC-Unique: xn9O0kKQP_SJuFmmCXiaoQ-1 Received: by mail-lf1-f69.google.com with SMTP id 2adb3069b0e04-539f5f33333so3704230e87.1 for ; Tue, 05 Nov 2024 03:09:11 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1730804950; x=1731409750; 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=4jxkOUZ57nYetmoWY3mq2h4CNdsjkQ08TdFmJGUwEmA=; b=H+rswDYXQSTf24yEXBGIyy+OOCgHmH81YpxDRk9SYimFce0PS54Ux7aJRcvUQ/qeO6 skwHBQN1sKwqDdM8OZn58wr0bn7cb9qIJIdWqrcZjfhPzUXQ7+se5S7ewym7WjIysBog gBuvuCTI78ljvED8LejJby51Lrha2ntKXW47D1w7efIfhj4af21zsMzvENEDL5qGhcju XDFLV/u37D7/cDEYmjnKJO9dcBWtDvc5pe0BjMRazoHP50D/KZSQwF4luI+FYVhPiv9t wb9WjlhgWVcS4cZTI+k01IftEbMYCAja7592JnbUp19cU75GWyKzBvLv2Q85b4NrexTi r23w== X-Forwarded-Encrypted: i=1; AJvYcCWk/LGk+ebqauQnM4Em5FMN3zmsFIHRZoUCPl2Sqg6F+cqFhHdB+gNhXEiwd1tYdIg+qtqDz05shw==@kvack.org X-Gm-Message-State: AOJu0YzXD2Rm4xr+cVJtXm7HA1wmZDm0IbTdrJMYNJHCP+rKDFUW7XAf MUte6WY6avW6F+nlI8vvmkQ9g3oiYI2gum9rYL5md0eYEa15rpS2KIkPD/khenKo6k37KGCnRzf 8mAuJv3muK9efMvcO1RHvhTentN+f1xs426/pNb967/bujeTp X-Received: by 2002:a05:6512:2244:b0:535:6942:29ea with SMTP id 2adb3069b0e04-53d65de556dmr6356910e87.11.1730804950022; Tue, 05 Nov 2024 03:09:10 -0800 (PST) X-Google-Smtp-Source: AGHT+IEC7vI1ZgJ/cqSMvmxJjC/r6wbYIsRGDH/dCPUq1Vh0OAmX5xLaj7wmGtoEZwSDgoeP0VaSOw== X-Received: by 2002:a05:6512:2244:b0:535:6942:29ea with SMTP id 2adb3069b0e04-53d65de556dmr6356874e87.11.1730804949483; Tue, 05 Nov 2024 03:09:09 -0800 (PST) Received: from ?IPV6:2003:cb:c73b:db00:b0d7:66ca:e3e9:6528? (p200300cbc73bdb00b0d766cae3e96528.dip0.t-ipconnect.de. [2003:cb:c73b:db00:b0d7:66ca:e3e9:6528]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4327d6852d9sm185454575e9.37.2024.11.05.03.09.08 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 05 Nov 2024 03:09:08 -0800 (PST) Message-ID: <7e04c8d3-b92e-400d-a1dd-f5902749f6d4@redhat.com> Date: Tue, 5 Nov 2024 12:09:07 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] mm: count zeromap read and set for swapout and swapin To: Barry Song <21cnbao@gmail.com> Cc: Andrew Morton , Usama Arif , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Barry Song , Chengming Zhou , Yosry Ahmed , Nhat Pham , Johannes Weiner , Hugh Dickins , Matthew Wilcox , Shakeel Butt , Andi Kleen , Baolin Wang , Chris Li , "Huang, Ying" , Kairui Song , Ryan Roberts References: <20241102101240.35072-1-21cnbao@gmail.com> <6c14ab2c-7917-489b-b51e-401d208067f3@gmail.com> <3f943f72-59d6-4124-96b2-e0bb8d7a5ebd@redhat.com> <20241104194024.0284288a28a71a70a3eab9b0@linux-foundation.org> <942f8355-4b23-4fd9-b00e-1121552d89ee@redhat.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: 8bit X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 5BC69160023 X-Stat-Signature: f9sute499fc3duy9zkxhs46tg8txt8zg X-Rspam-User: X-HE-Tag: 1730804932-245063 X-HE-Meta: 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 apg0czIx jm1MWtqiKZ6RdrUlrkDEIYy+h8awo02MYfGtKSsDdb0taPbNgY29Or+Raljj53Nb8FSPfW41N6PE1QdzeOD9TDgS2zkaLHRE5gK4JDy7Gc86gx3CC9Y15JM8u775M0wZJwDkUyTYdLFOEsBhfSEfJYAChaPiOjdqbcaG9uG8YRhTPiOvUGPi6Cz/pyHpMx39Mld6YcBM55n1+lL+YmK3wrwI6l7a2CsH+HTfYx3RRFiTjpCPsA0TXUhIGs8V9waBAmmpOxOt/nr9W0m7YfP6PaxTK/Bp5MmiPT+Ydtl6r/5BwQgWmMKv4qHODI+f7BOYU8Vnh6t5VWDwpW8DgQ5pUOEQ2FdtpK2abMYcG8aj0oSuruy7iz1IEtHHWF60G2oLykpRUoNpfsW/oJae4v/D/zdE1NlX3zaw6AtiD+SovIldSUUqy2gXuqMlkmuIWUU3I7Mdj 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 05.11.24 10:15, Barry Song wrote: > On Tue, Nov 5, 2024 at 9:23 PM David Hildenbrand wrote: >> >> On 05.11.24 04:40, Andrew Morton wrote: >>> On Mon, 4 Nov 2024 13:32:55 +0100 David Hildenbrand wrote: >>> >>>>> As mentioned above, this isn't about fixing a bug; it's simply to ensure >>>>> that swap-related metrics don't disappear. >>>> >>>> Documentation/process/submitting-patches.rst: >>>> >>>> "A Fixes: tag indicates that the patch fixes an issue in a previous >>>> commit. It is used to make it easy to determine where a bug originated, >>>> which can help review a bug fix." >>>> >>>> If there is no BUG, I'm afraid you are abusing that tag. >>> >>> I think the abuse is reasonable. We have no Should-be-included-with:. >> >> A "Belongs-to:" might make sense, for this kind of stuff that is still >> only in an RFC. Or we update the doc to explicitly spell out this >> special case of using "Fixes" to sort out something into the RC. >> >> Because if this would be already in a released kernel, it would get a >> bit trickier: stable rules explicitly spell out "fix a real bug". >> >>> >>> 0ca0c24e3211 is only in 6.12-rcX so this is the time to make >>> userspace-visible tweaks, so the 6.12 interfaces are the same as the >>> 6.13+ interfaces (which is what I think is happening here?) >> > > And including the Fixes in this patch might be useful to someone who is >>> backporting 0ca0c24e3211 into some earlier kernel for their own >>> purposes. >> >> Just to be clear: adding new counters would hardly be fixing existing >> tools that perform calculations based on existing counters. So we are >> already changing the "userspace-visible" portion in some way, and I have >> no idea what in vmstat we consider "stable". >> >> But I still don't think it's all that big of a deal except in some >> handcrafted scenarios hardly anybody cares about; the cover letter is >> also pretty clear on that. > > I may have been mistaken in the cover letter. According to the zswap data Usama > provided for servers, zero-filled pages accounted for about 1%. So > really doesn't > matter too much, but I just checked with Hailong from our team—he has data > on same-page-filled usage in Android apps, which on average show 3-4% > same-page-filled, with over 85% being zero-filled. Some apps even reach > 6-7% zero-filled pages. We previously used these counters to profile > optimizations, but with zeromap now serving as the frontend for swap files, > those counters will disappear entirely from both zRAM and pswpin/pswpout > metrics, as folios are filtered earlier. > > Hailong essentially has a table that looks like the below which could be > collected from the existing counters: > > com.xxx.app 5% same-page-filled. 88% zero > com.yyy.app 6% same-page-filled. 85% zero > com.zzz.map 6.7 same-page-filled. 88% zero > .... > > Anyone on 6.12 will be unable to track zero-filled pages unless they > backport this patch from a newer kernel version if it doesn’t make it > into 6.12. > > Whether it's marked as 'Belongs-to:' or 'Fixes:', I'd prefer we aim to > land it in > 6.12 :-) Thanks for sharing these numbers. Just for the records, I think the optimization is quite powerful. What I am not convinced is that the missing stat is a big deal. If I upgrade my car and it suddenly consumes 5% less fuel/energy I (a) either won't notice at all or (b) am happy and don't care why; I won't start digging through the updated manual, looking for some hidden gages that might explain why :) But I might be missing something important, and I do understand why it can be helpful to have it black-on-white how much this optimization gives you. So feel free to move forward with this as you like, having it in 6.12 sounds very reasonable to me. -- Cheers, David / dhildenb