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 087B9C4332F for ; Thu, 14 Dec 2023 13:33:47 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 96C6B8D00BA; Thu, 14 Dec 2023 08:33:46 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 8F4138D00B1; Thu, 14 Dec 2023 08:33:46 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 7948E8D00BA; Thu, 14 Dec 2023 08:33:46 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id 636DA8D00B1 for ; Thu, 14 Dec 2023 08:33:46 -0500 (EST) Received: from smtpin25.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id 38C8F120BD8 for ; Thu, 14 Dec 2023 13:33:46 +0000 (UTC) X-FDA: 81565516452.25.15630D3 Received: from mail-oo1-f49.google.com (mail-oo1-f49.google.com [209.85.161.49]) by imf05.hostedemail.com (Postfix) with ESMTP id 455AF10001D for ; Thu, 14 Dec 2023 13:33:44 +0000 (UTC) Authentication-Results: imf05.hostedemail.com; dkim=pass header.d=bytedance.com header.s=google header.b=kDfCd5+k; spf=pass (imf05.hostedemail.com: domain of zhouchengming@bytedance.com designates 209.85.161.49 as permitted sender) smtp.mailfrom=zhouchengming@bytedance.com; dmarc=pass (policy=quarantine) header.from=bytedance.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1702560824; 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=TGQSpV/olTYn464XLvf+Bx7XCT2e+qVX0TS6kVY/Gjg=; b=UVhAM8Mw76bGJ06iKeUeCc3kuvcB4b7B/jdKhTLE5uMYMQWJOsCfaqtSiajhLUNzMFb9to utlpj4FjrszkMtqpOkKXuA5BgjatTYq204/6EsvWwSEQJFAMvo2ADpmvziLhMyw1jY+3Vp o8qJnsv/Hnc3bI78IGbul82fgHjmFfY= ARC-Authentication-Results: i=1; imf05.hostedemail.com; dkim=pass header.d=bytedance.com header.s=google header.b=kDfCd5+k; spf=pass (imf05.hostedemail.com: domain of zhouchengming@bytedance.com designates 209.85.161.49 as permitted sender) smtp.mailfrom=zhouchengming@bytedance.com; dmarc=pass (policy=quarantine) header.from=bytedance.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1702560824; a=rsa-sha256; cv=none; b=qVqC49upz2gaw0t9aDah5FBOvoboUvqLgoNiMdeBOIgHCk1Nm8csdDYcinGLF140HRga13 ubdy6i3M5rR4S4kX0DJnHx/fsTiOUNH5T91cOl84M+r+6UfNCGvSb4U1yY4uL+6m42UYCT dFdZxZa4YCbQM3iFKSicxYzRnMPBimc= Received: by mail-oo1-f49.google.com with SMTP id 006d021491bc7-58a7d13b00bso4849660eaf.1 for ; Thu, 14 Dec 2023 05:33:43 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance.com; s=google; t=1702560823; x=1703165623; darn=kvack.org; h=content-transfer-encoding:in-reply-to:from:references:cc:to :content-language:subject:user-agent:mime-version:date:message-id :from:to:cc:subject:date:message-id:reply-to; bh=TGQSpV/olTYn464XLvf+Bx7XCT2e+qVX0TS6kVY/Gjg=; b=kDfCd5+kcxuvNiukxr9Dsy0QI1qEw2q5ARNB1Z7zZBIB2lOEuAQWuulwwd2wU+sZ5P pCNFoeIx9kvcQvvSQ8ujwzjjgUjqaChDCFmuBhTjRlIe6klmzYn8aBm3Yl5MVtaCKChM HVWNoFAjwhn+VggSbxVYLlcvAg1aNwwmXpJD/nK6HplX9KkZTkM4XNH+PmznfmTxKXeQ 6aCQZXLWvRue2OKpTFxlJ4zg5OLDurObucpyOBe0+qKhTTjIZmHyi1DjAQG757QQitnb 4qpDmhUm39N4ylUzoN9CJER7KGKkW6qKbF5gcAqDwVLhoKRQKmCnQA6Xo0z8Fx6h0UHO 7sBA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1702560823; x=1703165623; h=content-transfer-encoding:in-reply-to:from:references:cc:to :content-language:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=TGQSpV/olTYn464XLvf+Bx7XCT2e+qVX0TS6kVY/Gjg=; b=CWK9bz8Qyz67icqnwzHKSgoKeGRemumy0PDdsCkHT89dVgGOzF+YSl53Q9pMITLXJN Syon0YhWZo8FNKEsADKGrIHNX6vPDmBqZRDqwMU83Uig9FVP5BFG4BwDlyPjORhWA5TV lPJ1/sDAEdn2HCs9xA/s74iBKo8GGmog3dWLtB7TKrAxuv3cl8O/8jbLKgr5ZrJweJUC v/73EElAvRPTItuvnnTVSkC01vEXvDUwiR7Jo6hdBG1cjDsfKvYRcjLcIGb/HbW6Zh1Z LT/gxKYWyCQZB5aomm+ddAaJ5cgzW6OsBmedI8rgpdB/MmwsyL1XlVXrhW8K89ePA6dJ 9usw== X-Gm-Message-State: AOJu0YydZV1mCR64tw2FAerbS+dchz+lVQs5sxqwk3nRPM6B43XoJzIP sUTPxsWdxjPNwl5u4rm4rDbmoQ== X-Google-Smtp-Source: AGHT+IEsgLO6mOi7JT+gprO/GPP7X7B/o7SXKZV0aL/La/Rx0XOY2ck3DS7xg7ciCvCv5QR4TqyRfg== X-Received: by 2002:a05:6359:2e03:b0:170:17eb:3785 with SMTP id ro3-20020a0563592e0300b0017017eb3785mr7794874rwb.45.1702560823021; Thu, 14 Dec 2023 05:33:43 -0800 (PST) Received: from ?IPV6:2409:8a28:e64:34f0:4525:57e4:217e:6e2c? ([2409:8a28:e64:34f0:4525:57e4:217e:6e2c]) by smtp.gmail.com with ESMTPSA id n37-20020a634d65000000b005c21c23180bsm11638794pgl.76.2023.12.14.05.33.39 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 14 Dec 2023 05:33:42 -0800 (PST) Message-ID: Date: Thu, 14 Dec 2023 21:33:34 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 2/5] mm/zswap: change dstmem size to one page Content-Language: en-US To: Nhat Pham , Yosry Ahmed Cc: Andrew Morton , Chris Li , Johannes Weiner , Seth Jennings , Dan Streetman , Vitaly Wool , linux-kernel@vger.kernel.org, linux-mm@kvack.org References: <20231213-zswap-dstmem-v1-0-896763369d04@bytedance.com> <20231213-zswap-dstmem-v1-2-896763369d04@bytedance.com> From: Chengming Zhou In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 455AF10001D X-Rspam-User: X-Stat-Signature: wf8dx5xep59whdfa438beig9rkjngri5 X-Rspamd-Server: rspam01 X-HE-Tag: 1702560824-687663 X-HE-Meta: U2FsdGVkX19Htlz/DPALjxlExlbogE4EBH6wZSh21XzhuKLAbnLP/Wt1jB3ZcpcWIB0uJ/rH4p87kyFrtfId4v6sb1KPfi3oBqTITpvzPbZl0URrfTKWoCMWDyx8LVVbEC/mQvqpIGZ2+wORnMdqdJne1a/7HHruA1a13dEZF8LigNHsZuHW8yH+Sb0rjmn4lLETog3PaNtW6MOAAOVm6QRB8kGCDTBHbmzhV+m6B0JkQJuHR/lSOwlBtxb5xqEW+hM/2nO3qKlk4V7vh/S+2s8MlJFFb79/QPKuEtMNmwouQup8i8z78KIDuwR+4FDJzqdzHkVw0RlpIOWZFXF4o7VR4fUDEQiJmGXAu7OmRXv4tDP5M0uSZGkXkYaZhg810efrgpx16ADTFIVEmB1UuXa2MqEhYvy86asTn6PeIh53W3EBzv4j29FpsI8VmdFbTIWMMS8jeFyZA1nc/qIf7SJ3vyJNtLxPwEY4Amh+8dWbBPo+G8793kl4AtXpyzSfny1Le6yU1kPRMhzC15b+xEgu6BLzdExIG4q8zQZwCaJ/eYUMp9Qa84ZfYOg/P1XtLzwVgg7Xrx31+vrFqF9w9maemLCITB+J+kZyxUk1pfkBqy7uzugmrGU6FflDX2ueevPGyOYmzXIYUgaES9yY86AvadvamI6GdUJRAcxzk9mVb3tJwKtR5BWTr4WGUnB30vuMAqOhSAhxQAktW8n8D2OAIVKlZQafLY+EByPOFhyVL3+EUckA33tteZ7ft6pl6RXfRROR7oPLTeHtNOBB4SC0Vz7m4p1EGLDLeBzNXH9q+cNh4TXk+PtVdvltYxgX7db/AyxEIKxUm/0EyR1w4JWsKfPoNhYY3jUnDfa/uAQLsWYC86rpQqb+K39R79puIojQH+DT5uQGUUo7O+4CMdW2aXMF/3DmaI6++azkeuhgH00ClFhUTbnKfN3cBpOeugEOkNAgNUB3sad2lpQ IvnJ+QHc 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000007, 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 2023/12/14 08:18, Nhat Pham wrote: > On Wed, Dec 13, 2023 at 3:34 PM Yosry Ahmed wrote: >> >> On Tue, Dec 12, 2023 at 8:18 PM 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. Right, there is no any history about the reason why we needed 2 pages. But obviously only one page is needed from the current code and no any problem found in the kernel build stress testing. Thanks!