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=-3.5 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS 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 A62CDC4332B for ; Fri, 20 Mar 2020 17:48:57 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 6A8C82072C for ; Fri, 20 Mar 2020 17:48:57 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="h1Kzauch" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6A8C82072C Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 0FD706B0003; Fri, 20 Mar 2020 13:48:57 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 0AE3D6B0005; Fri, 20 Mar 2020 13:48:57 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id F06166B0007; Fri, 20 Mar 2020 13:48:56 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0008.hostedemail.com [216.40.44.8]) by kanga.kvack.org (Postfix) with ESMTP id D62746B0003 for ; Fri, 20 Mar 2020 13:48:56 -0400 (EDT) Received: from smtpin16.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 62A276D8A for ; Fri, 20 Mar 2020 17:48:56 +0000 (UTC) X-FDA: 76616476272.16.wave78_4e05fd1094d47 X-HE-Tag: wave78_4e05fd1094d47 X-Filterd-Recvd-Size: 3358 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) by imf10.hostedemail.com (Postfix) with ESMTP for ; Fri, 20 Mar 2020 17:48:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=REJDSQBSjlxGvUa9yFvVpoZkbE4uGtyMxtUffkDr/yg=; b=h1KzauchMVn1GcHidDQlLm4NDv aK4kqaKyat0c5S0apNaFmVi2M8lBpKqc6HcaPGEx+FFNw4NjYR32w5n0WAiLlaQiNyEfedB+7qoTL E/THmbYmMV4oouS6HA97h/6mPTqu5anVComDHxmPW4cHFSSyakaX+gQtXZhMNNfMHvVSjwaoJ0h2L OUdg+DUV4zfIM1jYNB9gSyndXuMPQpPpoePO6Xnc1zLjP/inzuV8mvsbNGEKjizrXkCo/5ONaqRd7 SqjRvCtsua+M1JEUo9eCXIRJNJsizFMS59zha5v/io1cPAKUeptHjpuXzj4A/3UtnQK12YL/XylLS RApjCAiA==; Received: from willy by bombadil.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1jFLlI-0000w5-Ps; Fri, 20 Mar 2020 17:48:48 +0000 Date: Fri, 20 Mar 2020 10:48:48 -0700 From: Matthew Wilcox To: Eric Biggers Cc: Andrew Morton , linux-xfs@vger.kernel.org, William Kucharski , linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, cluster-devel@redhat.com, linux-mm@kvack.org, ocfs2-devel@oss.oracle.com, linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-erofs@lists.ozlabs.org, linux-btrfs@vger.kernel.org Subject: Re: [PATCH v9 20/25] ext4: Convert from readpages to readahead Message-ID: <20200320174848.GC4971@bombadil.infradead.org> References: <20200320142231.2402-1-willy@infradead.org> <20200320142231.2402-21-willy@infradead.org> <20200320173734.GD851@sol.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200320173734.GD851@sol.localdomain> 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 Fri, Mar 20, 2020 at 10:37:34AM -0700, Eric Biggers wrote: > On Fri, Mar 20, 2020 at 07:22:26AM -0700, Matthew Wilcox wrote: > > From: "Matthew Wilcox (Oracle)" > > > > Use the new readahead operation in ext4 > > > > Signed-off-by: Matthew Wilcox (Oracle) > > Reviewed-by: William Kucharski > > --- > > fs/ext4/ext4.h | 3 +-- > > fs/ext4/inode.c | 21 +++++++++------------ > > fs/ext4/readpage.c | 22 ++++++++-------------- > > 3 files changed, 18 insertions(+), 28 deletions(-) > > > > Reviewed-by: Eric Biggers > > > + if (rac) { > > + page = readahead_page(rac); > > prefetchw(&page->flags); > > - list_del(&page->lru); > > - if (add_to_page_cache_lru(page, mapping, page->index, > > - readahead_gfp_mask(mapping))) > > - goto next_page; > > } > > Maybe the prefetchw(&page->flags) should be included in readahead_page()? > Most of the callers do it. I did notice that a lot of callers do that. I wonder whether it (still) helps or whether it's just cargo-cult programming. It can't possibly have helped before because we did list_del(&page->lru) as the very next instruction after prefetchw(), and they're in the same cacheline. It'd be interesting to take it out and see what happens to performance.