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=-2.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 0D72AC34022 for ; Wed, 19 Feb 2020 03:24:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D705C24658 for ; Wed, 19 Feb 2020 03:24:51 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=nvidia.com header.i=@nvidia.com header.b="UT3JHa9G" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726817AbgBSDYq (ORCPT ); Tue, 18 Feb 2020 22:24:46 -0500 Received: from hqnvemgate24.nvidia.com ([216.228.121.143]:16425 "EHLO hqnvemgate24.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726467AbgBSDYq (ORCPT ); Tue, 18 Feb 2020 22:24:46 -0500 Received: from hqpgpgate102.nvidia.com (Not Verified[216.228.121.13]) by hqnvemgate24.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA) id ; Tue, 18 Feb 2020 19:23:35 -0800 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate102.nvidia.com (PGP Universal service); Tue, 18 Feb 2020 19:24:46 -0800 X-PGP-Universal: processed; by hqpgpgate102.nvidia.com on Tue, 18 Feb 2020 19:24:46 -0800 Received: from [10.110.48.28] (10.124.1.5) by HQMAIL107.nvidia.com (172.20.187.13) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Wed, 19 Feb 2020 03:24:45 +0000 Subject: Re: [PATCH v6 07/19] mm: Put readahead pages in cache earlier To: Matthew Wilcox CC: , , , , , , , , , References: <20200217184613.19668-1-willy@infradead.org> <20200217184613.19668-12-willy@infradead.org> <20200219010209.GI24185@bombadil.infradead.org> From: John Hubbard X-Nvconfidentiality: public Message-ID: Date: Tue, 18 Feb 2020 19:24:45 -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: <20200219010209.GI24185@bombadil.infradead.org> X-Originating-IP: [10.124.1.5] X-ClientProxiedBy: HQMAIL105.nvidia.com (172.20.187.12) To HQMAIL107.nvidia.com (172.20.187.13) Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1582082615; bh=ZlagFYC7xJwJLLO9AWUODeIShplyyORjVfFAOxTHQbA=; h=X-PGP-Universal:Subject:To:CC:References:From:X-Nvconfidentiality: Message-ID:Date:User-Agent:MIME-Version:In-Reply-To: X-Originating-IP:X-ClientProxiedBy:Content-Type:Content-Language: Content-Transfer-Encoding; b=UT3JHa9GumLgpABiUIYS6tLJDf3T0qe2BkLDiRHe+ga+cBFPusc4s18OsMU/jLBlX E0NSDh7Wn3KmDNpXg+BOI8lgzx9nuhlOISv7Q+A953Wjg9k/Zip3jhxQxFwxXrhrTe mlzaTkOvirZ1Dkj3aIXO2/ZqisJThErxhVI/lGBx6uo30YWSEpJjJbA16XPG9BlUce E3OEkzQk82BcTRY/VG+SWUggGD+iAn6jEAnm7mW6H40rjA32wi90YTYCvMNdy0ZikV ycz4GiE2GTViYC1vPo+1mK6ZrNv30Kr16tydwj5IHm3yOemZstl28tkGDlc3/UIRIS mLk08n5euWN9Q== Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On 2/18/20 5:02 PM, Matthew Wilcox wrote: > On Tue, Feb 18, 2020 at 04:01:43PM -0800, John Hubbard wrote: >> How about this instead? It uses the "for" loop fully and more naturally, >> and is easier to read. And it does the same thing: >> >> static inline struct page *readahead_page(struct readahead_control *rac) >> { >> struct page *page; >> >> if (!rac->_nr_pages) >> return NULL; >> >> page = xa_load(&rac->mapping->i_pages, rac->_start); >> VM_BUG_ON_PAGE(!PageLocked(page), page); >> rac->_batch_count = hpage_nr_pages(page); >> >> return page; >> } >> >> static inline struct page *readahead_next(struct readahead_control *rac) >> { >> rac->_nr_pages -= rac->_batch_count; >> rac->_start += rac->_batch_count; >> >> return readahead_page(rac); >> } >> >> #define readahead_for_each(rac, page) \ >> for (page = readahead_page(rac); page != NULL; \ >> page = readahead_page(rac)) > > I'm assuming you mean 'page = readahead_next(rac)' on that second line. > > If you keep reading all the way to the penultimate patch, it won't work > for iomap ... at least not in the same way. > OK, so after an initial look at patch 18's ("iomap: Convert from readpages to readahead") use of readahead_page() and readahead_next(), I'm not sure what I'm missing. Seems like it would work...? thanks, -- John Hubbard NVIDIA