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 32CB8C0218A for ; Thu, 30 Jan 2025 16:30:01 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id BDF502802AF; Thu, 30 Jan 2025 11:30:00 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id B67A12802AD; Thu, 30 Jan 2025 11:30:00 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A2F342802AF; Thu, 30 Jan 2025 11:30:00 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id 841DC2802AD for ; Thu, 30 Jan 2025 11:30:00 -0500 (EST) Received: from smtpin21.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id 3DB92160267 for ; Thu, 30 Jan 2025 16:28:49 +0000 (UTC) X-FDA: 83064651978.21.5CA5188 Received: from mail-qt1-f175.google.com (mail-qt1-f175.google.com [209.85.160.175]) by imf17.hostedemail.com (Postfix) with ESMTP id A028D40014 for ; Thu, 30 Jan 2025 16:28:46 +0000 (UTC) Authentication-Results: imf17.hostedemail.com; dkim=pass header.d=cmpxchg-org.20230601.gappssmtp.com header.s=20230601 header.b=GMo4CBuM; spf=pass (imf17.hostedemail.com: domain of hannes@cmpxchg.org designates 209.85.160.175 as permitted sender) smtp.mailfrom=hannes@cmpxchg.org; dmarc=pass (policy=none) header.from=cmpxchg.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1738254527; 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: in-reply-to:in-reply-to:references:references:dkim-signature; bh=5OkXXACOng+utnMeMDItBc+7N83xw5BMkcJgXetJOrs=; b=Y1WNIHbdk6NfwmJKP4IGeaKZywZ2eJOo2a4L1sgmew1Lhe7lbDb/k5cENm0jWqjAR4t41E YqzooSorl50K5R5YveP40Cs3u3wOILTd4m5TVTHXADL7lfsfKLanwYxLycc7mUl+I9EI18 AooE4PouMVYXIJiaYO3EQ12vgm4po84= ARC-Authentication-Results: i=1; imf17.hostedemail.com; dkim=pass header.d=cmpxchg-org.20230601.gappssmtp.com header.s=20230601 header.b=GMo4CBuM; spf=pass (imf17.hostedemail.com: domain of hannes@cmpxchg.org designates 209.85.160.175 as permitted sender) smtp.mailfrom=hannes@cmpxchg.org; dmarc=pass (policy=none) header.from=cmpxchg.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1738254527; a=rsa-sha256; cv=none; b=061JxD5YhdeMkZ5AZKB7KNgYDZRDiTCxfh5drgfeG/byq1Swmo7JtbVqlclVgGwK3YkzL2 qSS9x3JYDH3gxOSDgZrzxGVqHi7UFlvRQRgsrr/QtpUksQNJHvt/56k0EX0FHA78KGxC1p fqQvawpSoXKJqGNMhcTTzLFJkUYuUfk= Received: by mail-qt1-f175.google.com with SMTP id d75a77b69052e-4679eacf2c5so8805421cf.0 for ; Thu, 30 Jan 2025 08:28:46 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cmpxchg-org.20230601.gappssmtp.com; s=20230601; t=1738254526; x=1738859326; darn=kvack.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=5OkXXACOng+utnMeMDItBc+7N83xw5BMkcJgXetJOrs=; b=GMo4CBuMOO1nA40zOdR10OttwrGn2Cz3U2NReG5n7wV2hnuxKkTkW/fEDezorjaJ7r u5dIP/ftfIXuYABNKTKWQOHYHgLKfPg0FbJMG+gE26awVQWMvCb+YEQ4vnW7ABSlAAkl 3o3uuGvuPxnXbXA6KpKEe253g+KqFwA1gYqiKgQ1pZ6mE5s+Ah4+jfyaMkcbj3ZG3lro EVVpmbSCnoCSBOvkeTMmPVjd4jTF5Vz5Qf1K693R9Knj9zoSz0ze3Cnve642rPlE4fQm a8c0m4qzLsz3ebb8vujpZvPB0VtKvyXHuMdfzYBK3faYzHU92p9eKzIgk6Xwxs1xBkOD v22A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1738254526; x=1738859326; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=5OkXXACOng+utnMeMDItBc+7N83xw5BMkcJgXetJOrs=; b=U1RMPbzmffbBVpKhlbyddwmL7JIPRh5PL9cwtfpSmdvOLIpvXPp3v4OCXO0/pnVUAQ N/wDdU5hAG8lBEUDuqO+sk2dd1P4VZKeSdAsMdEQhQUIWNvFjSY8U6fv5mSOq/PvAG36 WtmZtevhQO3jNDLvlFEfrTHA73swmjWW/FrtodxohqVG1HP6m+sNF7LzlPhA2I1Ida5g /+Xrd0X1LAg768zCqg5dO/MfX2IxgHLtaSQ/X1BiaJ3ydTc/hjR8Fe2quIfCfzH7l4PR TdB43fGnm4Dre6LT+NaSEuUlN9aELCjJoT6heQoX/yFTOrTQNqT8MGY4cs7An1nNuv8e KEPQ== X-Forwarded-Encrypted: i=1; AJvYcCVk07Buw9iQkXI7/aqho/fjlJc3kujtV3k1EM3+vQNHw3ZwIC3dsgEIeOtC8v/RXMkZPnFSik+l3w==@kvack.org X-Gm-Message-State: AOJu0YxTQxgcY+/eT2HhumopBYgIN8zPt+JaMjwMiNUj2HBhhhMWivZl WAwOVM/sGxEOrORaP5tVP3gnER+gmM71ryYHkAEJ/VXLvtK1kLCe67dBoIupIWs= X-Gm-Gg: ASbGncv/BKEyQVFoFh3SOTfhofG1GbTcqq75e/TsJXt/G1i9E5eGoLqvQFsIL/sd8+G rn7yia4pbYjE6iXx/XwgCSnBi47WzGdrLhm3W7nTghlvz/2PwGVBf0hingx27u3c6tH+yxAl82/ 2ZOyo67y1bKPHE2r+9PvPQ5U54V2F67g0/43oeL1JNi60hR3nrEwWeYgHCuETlBRA5nO9pFC9lT ZRl3oAeoU878li9WBlxpdX+dKy0rcyTbn3Wcfust/JqdehAJF/e+ren8NjqiAeKV6F/baxL3KAc osNs/dGZtU6bTA== X-Google-Smtp-Source: AGHT+IHdxC8d8mU2OcTkeT5tBiu59oWvGA29kh8nxXp/9u2SDZ/2GrNB5ZUbcdJsmkBEfXlqL2tQnQ== X-Received: by 2002:a05:6214:268e:b0:6d8:883b:142a with SMTP id 6a1803df08f44-6e243bef87emr112783916d6.2.1738254525734; Thu, 30 Jan 2025 08:28:45 -0800 (PST) Received: from localhost ([2603:7000:c01:2716:cbb0:8ad0:a429:60f5]) by smtp.gmail.com with UTF8SMTPSA id 6a1803df08f44-6e2547f4dacsm7757586d6.19.2025.01.30.08.28.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 30 Jan 2025 08:28:44 -0800 (PST) Date: Thu, 30 Jan 2025 11:28:36 -0500 From: Johannes Weiner To: Yosry Ahmed Cc: Andrew Morton , Vitaly Wool , Seth Jennings , Dan Streetman , Miaohe Lin , Nhat Pham , Chengming Zhou , Huacai Chen , WANG Xuerui , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Sven Schnelle , Shakeel Butt , Vlastimil Babka , linux-mm@kvack.org, linux-kernel@vger.kernel.org, loongarch@lists.linux.dev, linux-s390@vger.kernel.org, linux-doc@vger.kernel.org Subject: Re: [PATCH v2 2/2] mm: zbud: remove zbud Message-ID: <20250130162836.GA1283@cmpxchg.org> References: <20250129180633.3501650-1-yosry.ahmed@linux.dev> <20250129180633.3501650-3-yosry.ahmed@linux.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250129180633.3501650-3-yosry.ahmed@linux.dev> X-Rspamd-Queue-Id: A028D40014 X-Rspam-User: X-Rspamd-Server: rspam11 X-Stat-Signature: 56ixg38nm58pyqkt7qyrfjjyk15ox76s X-HE-Tag: 1738254526-171291 X-HE-Meta: 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 8NfxJ+4e 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000035, 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 Wed, Jan 29, 2025 at 06:06:32PM +0000, Yosry Ahmed wrote: > The zbud compressed pages allocator is rarely used, most users use > zsmalloc. zbud consumes much more memory (only stores 1 or 2 compressed > pages per physical page). The only advantage of zbud is a marginal > performance improvement that by no means justify the memory overhead. > > Historically, zsmalloc had significantly worse latency than zbud and > z3fold but offered better memory savings. This is no longer the case as > shown by a simple recent analysis [1]. In a kernel build test on tmpfs > in a limited cgroup, zbud 2-3% less time than zsmalloc, but at the cost > of using ~32% more memory (1.5G vs 1.13G). The tradeoff does not make > sense for zbud in any practical scenario. > > The only alleged advantage of zbud is not having the dependency on > CONFIG_MMU, but CONFIG_SWAP already depends on CONFIG_MMU anyway, and > zbud is only used by zswap. > > Remove zbud after z3fold's removal, leaving zsmalloc as the one and only > zpool allocator. Leave the removal of the zpool API (and its associated > config options) to a followup cleanup after no more allocators show up. > > Deprecating zbud for a few cycles before removing it was initially > proposed [2], like z3fold was marked as deprecated for 2 cycles [3]. > However, Johannes rightfully pointed out that the 2 cycles is too short > for most downstream consumers, and z3fold was deprecated first only as a > courtesy anyway. > > [1]https://lore.kernel.org/lkml/CAJD7tkbRF6od-2x_L8-A1QL3=2Ww13sCj4S3i4bNndqF+3+_Vg@mail.gmail.com/ > [2]https://lore.kernel.org/lkml/Z5gdnSX5Lv-nfjQL@google.com/ > [3]https://lore.kernel.org/lkml/20240904233343.933462-1-yosryahmed@google.com/ > > Signed-off-by: Yosry Ahmed Acked-by: Johannes Weiner