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 DC69FC4332F for ; Thu, 14 Dec 2023 00:18:42 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 2CB116B0396; Wed, 13 Dec 2023 19:18:42 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 278D36B0397; Wed, 13 Dec 2023 19:18:42 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 119B76B039A; Wed, 13 Dec 2023 19:18:42 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id E8EEB6B0396 for ; Wed, 13 Dec 2023 19:18:41 -0500 (EST) Received: from smtpin17.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay03.hostedemail.com (Postfix) with ESMTP id C6EBBA0BF7 for ; Thu, 14 Dec 2023 00:18:41 +0000 (UTC) X-FDA: 81563512842.17.916AC1D Received: from mail-io1-f53.google.com (mail-io1-f53.google.com [209.85.166.53]) by imf16.hostedemail.com (Postfix) with ESMTP id 1828B18000E for ; Thu, 14 Dec 2023 00:18:39 +0000 (UTC) Authentication-Results: imf16.hostedemail.com; dkim=pass header.d=gmail.com header.s=20230601 header.b=Wd3ys6sg; spf=pass (imf16.hostedemail.com: domain of nphamcs@gmail.com designates 209.85.166.53 as permitted sender) smtp.mailfrom=nphamcs@gmail.com; dmarc=pass (policy=none) header.from=gmail.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1702513120; a=rsa-sha256; cv=none; b=6C+VVMizUZIQTcJa8CjDU8GnNLSJDZAcBfbbq1xhuNvRHR4OSYMYGZws9pYHEBkbF2VNGo 40PfT4OIUH+Vxogj3+9YmtrEq/ygh8yDsb7H8AzN5PgSt3MWmW6gpLC0OfxcCnQJtmSllZ EYg6x/mu6l2JEemnuJ3IEY2gqUoSFj0= ARC-Authentication-Results: i=1; imf16.hostedemail.com; dkim=pass header.d=gmail.com header.s=20230601 header.b=Wd3ys6sg; spf=pass (imf16.hostedemail.com: domain of nphamcs@gmail.com designates 209.85.166.53 as permitted sender) smtp.mailfrom=nphamcs@gmail.com; dmarc=pass (policy=none) header.from=gmail.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1702513120; 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=UK0r9pqE3gS6uIIh7g6GkHrJnnAduy/j8HlB4vpg/WI=; b=CewJFgfHJJWI0oSuAqVzGe3j7jar3s6VV8DDkkRPHEh3uHTOD62ViZmNkZKBbkBH0RSuCc t8a1cP29AA8zpa/JGX81wTsGMJ0ywH25ahLyn1bKEkU66KQ0w+YVo1wxFcK+FVicnu3NP/ phPwwcyfVI8KUaLMsUtSEb/q1OqSozc= Received: by mail-io1-f53.google.com with SMTP id ca18e2360f4ac-7b71d65021dso2714739f.1 for ; Wed, 13 Dec 2023 16:18:39 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1702513119; x=1703117919; darn=kvack.org; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:from:to:cc:subject:date :message-id:reply-to; bh=UK0r9pqE3gS6uIIh7g6GkHrJnnAduy/j8HlB4vpg/WI=; b=Wd3ys6sgKbO6CcyKJTP4GzCEz58xDyMgGvLy1E6RYkOuofgogB3/73sfgmtZBR8AaM wJUE1wDHvZiaQSPSWIBYrqk8WOyqQu6/+x3wq+fO8nibZA84eIoM0ZoTNHsWOVVG0EJ/ dSRGV75uIayp5w+WL+s97kzUD1xl7Smte2Cy5DMLkvIqCXUtViJbUkjYISiOdG6WRB6r rN5gI6qVP8B8zM99L41L02s+mFVJv9vtu1KaoZ1f3EwulSbwIQoKdfsues7q53JzfIUl XnPAW2axfupeKtXcpHC9NyFpC51qZbjMPEzhSIBH/0FEEVS/3PtXfeuyd50YConkXQYv YnOQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1702513119; x=1703117919; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=UK0r9pqE3gS6uIIh7g6GkHrJnnAduy/j8HlB4vpg/WI=; b=R4R8wuPFBHiUeszPVbRxZ0CDju+a9jxuLI6yzhQF0xivzwhQah4T+JAfZdmGDaqwui Sew0C+K/jsB/DpfhYDZ32jCmYUIgFuJnGMmoVi06/ehQsRIbYqIzqc1Cfz1NldPV6CQx YRIGtFpoLY4jc7ciaFM++3neEE941wzw0vYlKn9KfV71EqM7MZnC0tb4ken4mlSz8nJx ODC67Oyeq3BD066dJzauUCNZXjrP13OY2YvzIE1vcomERhFdCGt4/4AFjib8TIssVsEQ A6g36vYY+p3CD1I8C6TLvrIp5AGVX5pZz0Gmh24U3Nu+VynqEVV7tnV+Y8D18YZ8OnLi ek9g== X-Gm-Message-State: AOJu0Yw1DFLXdpEsgDeCW4eduYe0HL1FRA/80OQWm7g25lOOZhQ58Anr dyfHTOTw0ujKqLLoIDu5xfYlwnJ1dmhso/yT2upOXuRca4sSeQ== X-Google-Smtp-Source: AGHT+IG4ZfHaO2lC9YISmdWm26tg0SSsfVW3vnRgOYFaM47aw206U8ol6cL+d8otxvq9aNlNm2nCeTZnzd/jiikBCL0= X-Received: by 2002:a6b:e81a:0:b0:7b4:2a4e:57b0 with SMTP id f26-20020a6be81a000000b007b42a4e57b0mr7965967ioh.11.1702513119140; Wed, 13 Dec 2023 16:18:39 -0800 (PST) MIME-Version: 1.0 References: <20231213-zswap-dstmem-v1-0-896763369d04@bytedance.com> <20231213-zswap-dstmem-v1-2-896763369d04@bytedance.com> In-Reply-To: From: Nhat Pham Date: Wed, 13 Dec 2023 16:18:28 -0800 Message-ID: Subject: Re: [PATCH 2/5] mm/zswap: change dstmem size to one page To: Yosry Ahmed Cc: Chengming Zhou , Andrew Morton , Chris Li , Johannes Weiner , Seth Jennings , Dan Streetman , Vitaly Wool , linux-kernel@vger.kernel.org, linux-mm@kvack.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 1828B18000E X-Stat-Signature: hsjm1ic84t9r4wo6ojdrsdc81wq986ro X-Rspam-User: X-HE-Tag: 1702513119-549125 X-HE-Meta: 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 3l5LWN2C L/a1ivljQ/NPAN9tkkcSEZ0qdew2qYAwi7bg3bAnpPpQVs8UtGcn+cNNKd23rwGbD0VH+FHRRecW6XAIyhj/6u0KnkOE81vTNm4l8VVrMRuVYayjSz1hkm5kmV5/Dc3yuHhHZfdd0HelA0tLyQ7oUAKkKOavdeGkCx+AZ1a4hiUUChCBrYhvUjCieF+A6+AnufuEu6eod7alUKVvSLB9ymoV2v2hKMrdaLf4+U9w4YYf5zdg2Y7hFc4XWSk8/6pBHjXWvHE/mxTy5qBpp/sfikVGthCwunhYDOfSrsBTMgjIFIVC1GQq+dEavbR0xDPNUOxc/FRKw8Fuff4qn5PPGjqaGQk9G73deswnhtcK2+yB4DcAw92Hb4YyuS6t7Gnd/f0bkfDJuoNphfS2PaGzE+3O5w1LStNMOxCzH+nvvH8oH51Y8EDXzMaBeoQ== X-Bogosity: Ham, tests=bogofilter, spamicity=0.001208, 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, Dec 13, 2023 at 3:34=E2=80=AFPM Yosry Ahmed = wrote: > > On Tue, Dec 12, 2023 at 8:18=E2=80=AFPM Chengming Zhou > wrote: > > > > Change the dstmem size from 2 * PAGE_SIZE to only one page since > > we only need at most one page when compress, and the "dlen" is also > > PAGE_SIZE in acomp_request_set_params(). If the output size > PAGE_SIZE > > we don't wanna store the output in zswap anyway. > > > > So change it to one page, and delete the stale comment. > > I couldn't find the history of why we needed 2 * PAGE_SIZE, it would > be nice if someone has the context, perhaps one of the maintainers. It'd be very nice indeed. > > One potential reason is that we used to store a zswap header > containing the swap entry in the compressed page for writeback > purposes, but we don't do that anymore. Maybe we wanted to be able to > handle the case where an incompressible page would exceed PAGE_SIZE > because of that? It could be hmm. I didn't study the old zswap architecture too much, but it has been 2 * PAGE_SIZE since the time zswap was first merged last I checked. I'm not 100% comfortable ACK-ing the undoing of something that looks so intentional, but FTR, AFAICT, this looks correct to me.