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 X-Spam-Level: X-Spam-Status: No, score=-2.2 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4E373C10DCE for ; Sat, 14 Mar 2020 02:56:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0E2562074B for ; Sat, 14 Mar 2020 02:56:25 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=gmx.net header.i=@gmx.net header.b="B/fZy2U0" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726785AbgCNC4Y (ORCPT ); Fri, 13 Mar 2020 22:56:24 -0400 Received: from mout.gmx.net ([212.227.17.22]:41997 "EHLO mout.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726559AbgCNC4X (ORCPT ); Fri, 13 Mar 2020 22:56:23 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gmx.net; s=badeba3b8450; t=1584154578; bh=i8WilJSytSDj6FNn0dPhu68n3IihdpdHTuKvjH6GW7A=; h=X-UI-Sender-Class:Subject:To:References:From:Date:In-Reply-To; b=B/fZy2U0lqK4wLkryjyZ0orqeRDwXYVnAI1AJjwjQTA/uEBs97XkdmKt4HVB+BWxL kSLnBfzDyvBljOTFOMoZ4DnzUM4OV94YH+TvBFaMbyhdRQWiJYKqXaQeY/rcN2NwZM viUl0lFUG/D2XCCn87mR7P+GKDjCZCvKjeowvHA4= X-UI-Sender-Class: 01bb95c1-4bf8-414a-932a-4f6e2808ef9c Received: from [0.0.0.0] ([149.28.201.231]) by mail.gmx.com (mrgmx104 [212.227.17.174]) with ESMTPSA (Nemesis) id 1MBDj4-1j1RBa2oUo-00CmQr; Sat, 14 Mar 2020 03:56:17 +0100 Subject: Re: [PATCH 0/2] Drop some mis-uses of READA To: Josef Bacik , linux-btrfs@vger.kernel.org, kernel-team@fb.com References: <20200313210954.148686-1-josef@toxicpanda.com> From: Qu Wenruo Autocrypt: addr=quwenruo.btrfs@gmx.com; prefer-encrypt=mutual; keydata= mQENBFnVga8BCACyhFP3ExcTIuB73jDIBA/vSoYcTyysFQzPvez64TUSCv1SgXEByR7fju3o 8RfaWuHCnkkea5luuTZMqfgTXrun2dqNVYDNOV6RIVrc4YuG20yhC1epnV55fJCThqij0MRL 1NxPKXIlEdHvN0Kov3CtWA+R1iNN0RCeVun7rmOrrjBK573aWC5sgP7YsBOLK79H3tmUtz6b 9Imuj0ZyEsa76Xg9PX9Hn2myKj1hfWGS+5og9Va4hrwQC8ipjXik6NKR5GDV+hOZkktU81G5 gkQtGB9jOAYRs86QG/b7PtIlbd3+pppT0gaS+wvwMs8cuNG+Pu6KO1oC4jgdseFLu7NpABEB AAG0IlF1IFdlbnJ1byA8cXV3ZW5ydW8uYnRyZnNAZ214LmNvbT6JAU4EEwEIADgCGwMFCwkI BwIGFQgJCgsCBBYCAwECHgECF4AWIQQt33LlpaVbqJ2qQuHCPZHzoSX+qAUCXZw1oQAKCRDC PZHzoSX+qCY6CACd+mWu3okGwRKXju6bou+7VkqCaHTdyXwWFTsr+/0ly5nUdDtT3yEVggPJ 3VP70wjlrxUjNjFb6iIvGYxiPOrop1NGwGYvQktgRhaIhALG6rPoSSAhGNjwGVRw0km0PlIN D29BTj/lYEk+jVM1YL0QLgAE1AI3krihg/lp/fQT53wLhR8YZIF8ETXbClQG1vJ0cllPuEEv efKxRyiTSjB+PsozSvYWhXsPeJ+KKjFen7ebE5reQTPFzSHctCdPnoR/4jSPlnTlnEvLeqcD ZTuKfQe1gWrPeevQzgCtgBF/WjIOeJs41klnYzC3DymuQlmFubss0jShLOW8eSOOWhLRuQEN BFnVga8BCACqU+th4Esy/c8BnvliFAjAfpzhI1wH76FD1MJPmAhA3DnX5JDORcgaCbPEwhLj 1xlwTgpeT+QfDmGJ5B5BlrrQFZVE1fChEjiJvyiSAO4yQPkrPVYTI7Xj34FnscPj/IrRUUka 68MlHxPtFnAHr25VIuOS41lmYKYNwPNLRz9Ik6DmeTG3WJO2BQRNvXA0pXrJH1fNGSsRb+pK EKHKtL1803x71zQxCwLh+zLP1iXHVM5j8gX9zqupigQR/Cel2XPS44zWcDW8r7B0q1eW4Jrv 0x19p4P923voqn+joIAostyNTUjCeSrUdKth9jcdlam9X2DziA/DHDFfS5eq4fEvABEBAAGJ ATwEGAEIACYCGwwWIQQt33LlpaVbqJ2qQuHCPZHzoSX+qAUCXZw1rgUJCWpOfwAKCRDCPZHz oSX+qFcEB/95cs8cM1OQdE/GgOfCGxwgckMeWyzOR7bkAWW0lDVp2hpgJuxBW/gyfmtBnUai fnggx3EE3ev8HTysZU9q0h+TJwwJKGv6sUc8qcTGFDtavnnl+r6xDUY7A6GvXEsSoCEEynby 72byGeSovfq/4AWGNPBG1L61Exl+gbqfvbECP3ziXnob009+z9I4qXodHSYINfAkZkA523JG ap12LndJeLk3gfWNZfXEWyGnuciRGbqESkhIRav8ootsCIops/SqXm0/k+Kcl4gGUO/iD/T5 oagaDh0QtOd8RWSMwLxwn8uIhpH84Q4X1LadJ5NCgGa6xPP5qqRuiC+9gZqbq4Nj Message-ID: <91bf00f3-a851-2e84-4213-761b0d776af2@gmx.com> Date: Sat, 14 Mar 2020 10:56:06 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 MIME-Version: 1.0 In-Reply-To: <20200313210954.148686-1-josef@toxicpanda.com> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="wvVLS2a5EMbhJGoIbZagD9OBIN2ruYrzZ" X-Provags-ID: V03:K1:+8X58wM9dcI/Gz/7AZzsHHNPFrQE+WFVuPC3kST1zVL50T1mmIw KobJYWhtCwvEuVRN3JJeoJNWOa76p8g+sZavSPf2LfM3lyM1yC2nVAPN/Qtl7Ks5MIK0Q2M DgP5gqY4omLkOxIuW96iVwG9bwJJ4mi4unDeYe+TQ8POGB6IDd0tbreN20ktM/tu2ET7a7b ScdidRW7eeEc6WBpDK+lw== X-UI-Out-Filterresults: notjunk:1;V03:K0:QgR80meXEIQ=:1T4VqWTpLDYD5Z2V8Ltsc7 AhEyDL1VuDSJ5mGsF1ITveU/z59Vz9vc7ujj33EokxEv86OAOJnKzbFNhbnrqfN9M6YfjNRN7 BjanRKpKRIwipceRSL67V2NjlPVdGrzmE/k7h8PIfeHQBdcY4FbptwU5VGmvRo4TZvT3m6ZlY 02/9v8yH9BJtx3VlL+YoL3vh93o1gcZGls4NnzpNsAI2Ke7/NoZuMBJ5Den8wflc+HZ2bCbcV /61/YX8Y/xOM6AehN3hzgzDy3iphmgD+I83glKQok3z0mxKJvY6Db0nQSfKvJlsudwR3mhkeD Ovljee+gFCjsI7kjMIC5Gm4MFrjIDuuN6buw1HYE/5A2/ebFof37EGm/N/p01hbden7a+jy45 qulVIJjPiUeaKbL5td84Y17TRxPSRGFBPIXWGNpqRI8nAqUYPr/8KgwN+lSOJP9A36TyyAvB1 wgvtRlXxNvNh/9tq2puVH/LF9u6MKXsSY7dPcQBLm7wuErCBqDfcldfK/gi5K4t9LfXTrD/z+ 8eX1FANXBp6gH1jEOiTO7g+9PIvD6Py5KfwY7Rmt3EyKU2aXBUPoHUeseDHWIX+8v6d19baWO YiTp0tKMuiie2ARSjoreRLruy/qkdoHrofieAIrAy6gFutCN2ahWEcmFJYsDP+SaFAJaci65W yUpDZXhOh2u+WgNlERUAbcSkOX6/JBFjFHT3W1LGx46L0pMd4BmA9kmc+BAIjknDRnDCYVDdf MYflrJVSLtjDm9RP8bbjz2Mama8r3+8pxn6+be5pq7ql6VLBg4DHFt5IMHpkgAaSj5cn7FFjy mHdviKqI7zZ0qWWXg5K7AOOCBhKlOFMRRoj816DgJ6ov35O2XkZg2zfI1CC5cHw3o5NVY4rkd ABk4kkUKg+LxG2FIak1mBQvsh5HLAT0vb4BOz+ONZmPBHFi3Zaz+tyB4B6Ki98fhyBW+iOsZs c8J+cGkBD/jjxHB3TJYIm38DmpC4ijMZu7aQo65LL13yINVc70KYIM0AN/uCrWCi3ihUgKIiX 2v+46cb5KhBTUlvkk4cR0+Yn7KjT7y0ebdWrZ/1UGVxYwPmhVlMJ35vi3vL1dnjPV9T/Ht1Y6 Wtb9PUvhQ/5dEZVdYPkAIm5bZnC9P0L/yqd78rsUbqTFnY0xAPRQkbRe8KyAeNu3mmzSBC8D8 +HFr6fW2KxSuZEiydcYLSutsgBr066FYG83GnxeQHzcGNO5sehe/X6fEG7j6M8yAvdgRncXYd kMJx6bgpyHKDuSDq+ Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --wvVLS2a5EMbhJGoIbZagD9OBIN2ruYrzZ Content-Type: multipart/mixed; boundary="wuu6DMcDUerMzPbSD97p3AxXEWdQCewyc" --wuu6DMcDUerMzPbSD97p3AxXEWdQCewyc Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 2020/3/14 =E4=B8=8A=E5=8D=885:09, Josef Bacik wrote: > In debugging Zygo's huge commit delays I noticed we were burning a bunc= h of time > doing READA in cases where we don't need to. The way READA works in bt= rfs is > we'll load up adjacent nodes and leaves as we walk down. This is usefu= l for > operations where we're going to be reading sequentially across the tree= =2E >=20 > But for delayed refs we're looking up one bytenr, and then another one = which > could be elsewhere in the tree. With large enough extent trees this re= sults in > a lot of unneeded latency. >=20 > The same applies to build_backref_tree, but that's even worse because w= e're > looking up backrefs, which are essentially randomly spread out across t= he extent > root. Thanks, There are quite some other locations abusing READA. E.g. btrfs_read_block_groups(), where we're just searching for block group items. There is no guarantee that next block group item is in next a few leaves. I guess it's a good time to review all READA abuse. Or would you mind me to do that? Thanks, Qu >=20 > Josef >=20 --wuu6DMcDUerMzPbSD97p3AxXEWdQCewyc-- --wvVLS2a5EMbhJGoIbZagD9OBIN2ruYrzZ Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEELd9y5aWlW6idqkLhwj2R86El/qgFAl5sR8YACgkQwj2R86El /qh5NggAouo2Ioe93UKepUaYz5+30jMYLha72fSb5YE3KN45qub92YyV6xg0xorF akxkmFK9VjWL6GcTQnpnHNz9LgHNfN8F56wW9qfHzmIrg7qRmTyIJMARMVMMeqSA TXCOD9Q48xD6Y7QhTEL+2VfKmhKLfUkI7h66E39X+kodjThrMrxANyoVrOvb56v6 67MD6mW8beYctJPiNMMwjd29MykkuCgUs2/cyJD3J3EmLmf/ySUxr6oD1+NudAII pibYX+3KVTrgZQcbqNDjxsP6DUpPoPCq18f3S5XPHDkS9ygvdHwBNP/bpGkFv8A0 niQFmlAU/6Ykt58X+n5L8DYashLEbw== =Cq8J -----END PGP SIGNATURE----- --wvVLS2a5EMbhJGoIbZagD9OBIN2ruYrzZ--