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=-3.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT 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 0E71FC433DF for ; Wed, 10 Jun 2020 00:10:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CF01C2078D for ; Wed, 10 Jun 2020 00:10:57 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="DH9f/24y" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726024AbgFJAKp (ORCPT ); Tue, 9 Jun 2020 20:10:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43910 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725797AbgFJAKn (ORCPT ); Tue, 9 Jun 2020 20:10:43 -0400 Received: from mail-qk1-x744.google.com (mail-qk1-x744.google.com [IPv6:2607:f8b0:4864:20::744]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7B03FC05BD1E; Tue, 9 Jun 2020 17:10:43 -0700 (PDT) Received: by mail-qk1-x744.google.com with SMTP id c14so410529qka.11; Tue, 09 Jun 2020 17:10:43 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=XFLCZdE5vvLdiZqFWAjPf5wwSUfiIU/6H0OECncmJWY=; b=DH9f/24yL7hrjzsDEOLLogDEMuNcGjw3g2xf9FJDwAwSBeIiDS2EjRpcJowMT4Q2mG hqcmY+idwS5s8ZPKI0hkCh0wBe9vx4QFsNLV5JUCKwBjrxHlncsQ0XiQCTUkFdBqH+v8 ctkBHHUz9K9TMJqMt3mDlUHxBg+oR+32DTv360E70nJ9DAV2o5+STSds/FnTN4Pu2CIm 7712HDNJuNo59JvyrNwVE3hynng2GHDOx3LS9nrcw+MNVz8XLUvo/24LcNqsXUrNuLi6 Dx3K70+dPRHr5rYGAtH6swOXJUQzTQ6NrpS7/058ZNaJiQIbfssyqRV4ifiI4Ecruv2p yJvw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=XFLCZdE5vvLdiZqFWAjPf5wwSUfiIU/6H0OECncmJWY=; b=D26T40/xqoMw+wQNeyVWvNUn0iNMaR4BjtQ2talqF0wo81ZtupHgvAdSx1WgdeR2bT ccOyDhXoUuagE21lE1tzwdfT1bc/TsgFmH2df5QFt8bb1G+8ZBUZ/bJCqOhcCUY9ewYh pU7NS+mpOdo+yMDocGgHwciGSgDK6veOKo4QMJs2zKFwcD4IPATXuGgy+BNTarKVcEh4 z7CGkal1zUVrn7/8ywPZCUb2n2mNtWKh+c7vv6I/fuUyDe0g6VxlaAtGAPmnaxYS8uZ2 Om+AlvS6WyJjxYaGPdocrsMeQYUs0l4Ht4T9aZN1zvoJtEoNbiunL6QBWYYXlaxQYiOw mgTQ== X-Gm-Message-State: AOAM530cAjFAKGNmhoFMTtaihitLz5MTR1kBvc4caY9ZeubZLsB/tUc1 gFHhZ4Lv8FXzL9P/HqzxvKZBUzw= X-Google-Smtp-Source: ABdhPJzsMjjBQX2I2CRruAFtRqgWtzvKsXzY5QaMLocolCxEE9yCB5Rt8Zlx1wd5tyDQ295jrJ1X5A== X-Received: by 2002:a05:620a:21cc:: with SMTP id h12mr525346qka.194.1591747841673; Tue, 09 Jun 2020 17:10:41 -0700 (PDT) Received: from moria.home.lan ([2601:19b:c500:a1:7285:c2ff:fed5:c918]) by smtp.gmail.com with ESMTPSA id c2sm1757836qkl.58.2020.06.09.17.10.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 09 Jun 2020 17:10:40 -0700 (PDT) From: Kent Overstreet To: linux-kernel@vger.kernel.org, akpm@linux-foundation.org, viro@zeniv.linux.org.uk, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org Cc: Kent Overstreet Subject: [PATCH 0/2] generic_file_buffered_read() refactoring & optimization Date: Tue, 9 Jun 2020 20:10:34 -0400 Message-Id: <20200610001036.3904844-1-kent.overstreet@gmail.com> X-Mailer: git-send-email 2.27.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This is a small patch series that's been in the bcachefs tree for awhile. In the buffered read path, we look up a page in the page cache, then copy from that page in a loop - i.e. mixing the data copies in between looking up each individual page. When we're doing large reads from the page cache, this is some pretty major overhead. This just reworks generic_file_buffered_read() to use find_get_pages_contig() and work on an array of pages. It's a pretty significant performance improvement for large buffered reads, and doesn't regress performance on single page reads. As a bonus, generic_file_buffered_read() gets broken up into multiple functions that are _somewhat_ easier to follow. Kent Overstreet (2): fs: Break generic_file_buffered_read up into multiple functions fs: generic_file_buffered_read() now uses find_get_pages_contig mm/filemap.c | 486 +++++++++++++++++++++++++++++---------------------- 1 file changed, 273 insertions(+), 213 deletions(-) -- 2.27.0