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 E4860C7EE23 for ; Sun, 21 May 2023 23:55:16 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 60419900002; Sun, 21 May 2023 19:55:16 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 5B4516B0075; Sun, 21 May 2023 19:55:16 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 47BAB900002; Sun, 21 May 2023 19:55:16 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id 385586B0074 for ; Sun, 21 May 2023 19:55:16 -0400 (EDT) Received: from smtpin17.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay05.hostedemail.com (Postfix) with ESMTP id 0653A402E1 for ; Sun, 21 May 2023 23:55:16 +0000 (UTC) X-FDA: 80815921032.17.F623A90 Received: from mail-pl1-f176.google.com (mail-pl1-f176.google.com [209.85.214.176]) by imf01.hostedemail.com (Postfix) with ESMTP id 46A8740006 for ; Sun, 21 May 2023 23:55:14 +0000 (UTC) Authentication-Results: imf01.hostedemail.com; dkim=pass header.d=google.com header.s=20221208 header.b=LjoD1Kst; dmarc=pass (policy=reject) header.from=google.com; spf=pass (imf01.hostedemail.com: domain of rientjes@google.com designates 209.85.214.176 as permitted sender) smtp.mailfrom=rientjes@google.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1684713314; 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=2jmWZnYj5XiM6LuwQooPUrSa5JnI7IaYCNdnUaCT5p8=; b=HDvk3OgNHKbAvSzIVWQgDWSKSCMigqfI88OgviUkk3Q4wlDrxQQyXEcz/odTJd5nou2Ihu EPwz0z1Qawfu8eI8Mq3AnQFF3zqUehTBYACOr8rT0iWk2Ac6/WRaPLiwGWXIvu1wUdDL0x fOL5f5lnV/aGESMRab0KBeRdmR5ZgKk= ARC-Authentication-Results: i=1; imf01.hostedemail.com; dkim=pass header.d=google.com header.s=20221208 header.b=LjoD1Kst; dmarc=pass (policy=reject) header.from=google.com; spf=pass (imf01.hostedemail.com: domain of rientjes@google.com designates 209.85.214.176 as permitted sender) smtp.mailfrom=rientjes@google.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1684713314; a=rsa-sha256; cv=none; b=TkHPjGUIWIicU2dnZcs5ZodcXV8cc8X+26wmV27yl6KGfzpGlU8Pt/mUbBOJ2IBBMSMmi4 8I1hjXM/BX/GHBtsqYYu5gX4BW3BzoLmXItFTnHeFi/GS/TNuCi405Xpdhs1xKynlOftmo /PRCtd8Bfh80kInudU/3z4L0YQZQ1PE= Received: by mail-pl1-f176.google.com with SMTP id d9443c01a7336-1a950b982d4so198465ad.0 for ; Sun, 21 May 2023 16:55:13 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20221208; t=1684713313; x=1687305313; h=mime-version:references:message-id:in-reply-to:subject:cc:to:from :date:from:to:cc:subject:date:message-id:reply-to; bh=2jmWZnYj5XiM6LuwQooPUrSa5JnI7IaYCNdnUaCT5p8=; b=LjoD1KstuPIIbtn1v+hXFZY/oxBCjdRD2KAJeG8eFcGHoZCPMtCF4unnylVTNPd4Rg bDeARlb+9q/xXv5BlHRtZaXmElu/9zJhb37LnhE5WjSXuo95xGUmaZbNfngBlosey7kH FVyuyWCLaCd61B3diL5tU3jp9WHsK4dDwdzk2hhMUpoLSIcjhTEpQrjTUV+RDEkAxrxC dRJXEPEo86FqFy7BSpr7cQiaTJdUh+DLpdlFOT/NzmW/gSnQR/ApJ9312gaoHaayI6sG S91ceMwuFF0vvnFxCKY4P4YB2nzNW6VfMLurUFFuFcMJ1YHa6+Zu5Tz3CzSqdg4gyrkQ v/uw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1684713313; x=1687305313; h=mime-version:references:message-id:in-reply-to:subject:cc:to:from :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=2jmWZnYj5XiM6LuwQooPUrSa5JnI7IaYCNdnUaCT5p8=; b=XpXVCeZno03jH2sgO9XNWuD0avSkYI1hnNRSaQodTf5PbdkBq3Fdvw+SbRxANtEdU3 KUTa2CXVzoW8dOUBIg/jCdOlI1bZfh0nhsLU2dTpP+OpNoO6FwlIS0N43IR/TVcWgnWh HKX7QT931lnZXEfVhY6I4yZnyU1gDh3aZtLC2d9RiPOYUL0D6Alu6Owk+LzDRJOt04Ow BDTc2odwjPavObKscKh1PXT+Xs1rhpZfNHUrtK2SwKehr3ibhJxJja65zRmNhmZu7ezu 1qYvmG8KePO2EeJoubLHBC936JYEdvS8fsJqNw1jrDXefYPissxyn1xWwQ0zrNMDFJgv cGgw== X-Gm-Message-State: AC+VfDycGDPdvDdm113aDvfUULt8t8MHvQwvC3ncf9ZjNrel2oiBW8bk DxqbMg/qJt2fIB0itNXLbKO0SA== X-Google-Smtp-Source: ACHHUZ52qhqgQUFh2dm9WwAzD8hKyyemsLBwKJKh9Sv5yolyeGJSUgt5bBQFztmEUqQedhSqmnXbag== X-Received: by 2002:a17:902:c94e:b0:1af:90ce:5263 with SMTP id i14-20020a170902c94e00b001af90ce5263mr253822pla.26.1684713313037; Sun, 21 May 2023 16:55:13 -0700 (PDT) Received: from [2620:0:1008:11:c77c:12d8:c868:4106] ([2620:0:1008:11:c77c:12d8:c868:4106]) by smtp.gmail.com with ESMTPSA id g8-20020aa78188000000b0064d42e66205sm2990168pfi.56.2023.05.21.16.55.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 21 May 2023 16:55:12 -0700 (PDT) Date: Sun, 21 May 2023 16:55:11 -0700 (PDT) From: David Rientjes To: Yuanchu Xie cc: Andrew Morton , "Liam R . Howlett" , Yang Shi , Zach O'Keefe , Peter Xu , "Kirill A . Shutemov" , Matthew Wilcox , Pasha Tatashin , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH] mm: pagemap: restrict pagewalk to the requested range In-Reply-To: <20230515172608.3558391-1-yuanchu@google.com> Message-ID: References: <20230515172608.3558391-1-yuanchu@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Rspamd-Queue-Id: 46A8740006 X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: kjtcmyoysyf74jywmhu4ao3ikxq6z357 X-HE-Tag: 1684713314-341356 X-HE-Meta: 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 kjeuQxby bK9Y8XltBAnTpWEJbXEsx/FPAEMDKJbco3oSCzYQ0NeKGXph2bV3mK5z8uWaKgAPzuKiobUdSlKXSxNuZKRN4eKJLVJHsFuvU2Dw+chyHFoe1MB4X8tLfawMIZiV9lYya/Ii/Lmd1gXvBfhTzUOV16yNZ7SM19DxmO3gjSb6+h9+MlFqbANfMGjAlzue/uYufVYnC1F/reVHVkp+96tVznXi9hafZUWTXeSq2eCjEVdmzHroULZwDzaHvJq+u+5e3hKg58ZFw20Sr+yYIxJooOsd682/n76WIcRjFErOovxZNHOkULz3FdKOnDRQDhFsd2vWgYxr+X83aRofP7bPFUjtOewKhQ+vZm+CAY+WYjKX6POOvKM0B/yrpwfeiRgnA5q6HSswAuEKzDwQtaNvLJiULG9fM1Dbcj26D 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: On Tue, 16 May 2023, Yuanchu Xie wrote: > The pagewalk in pagemap_read reads one PTE past the end of the requested > range, and stops when the buffer runs out of space. While it produces > the right result, the extra read is unnecessary and less performant. > > I timed the following command before and after this patch: > dd count=100000 if=/proc/self/pagemap of=/dev/null > The results are consistently within 0.001s across 5 runs. > > Before: > 100000+0 records in > 100000+0 records out > 51200000 bytes (51 MB) copied, 0.0763159 s, 671 MB/s > > real 0m0.078s > user 0m0.012s > sys 0m0.065s > > After: > 100000+0 records in > 100000+0 records out > 51200000 bytes (51 MB) copied, 0.0487928 s, 1.0 GB/s > > real 0m0.050s > user 0m0.011s > sys 0m0.039s > > Signed-off-by: Yuanchu Xie Acked-by: David Rientjes