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=-4.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, NICE_REPLY_A,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 32180C433DF for ; Fri, 14 Aug 2020 20:10:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0BDBA206DA for ; Fri, 14 Aug 2020 20:10:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597435838; bh=V1LBnLR6GD/H9lBrBNExcAJGbLLMmg8AfmNutpx8vGA=; h=Date:From:To:Cc:Subject:In-Reply-To:References:List-ID:From; b=Bkdh/sKIfuDL2sh0mE3JiOVuUPl3uk53QfZwkHcJyBmrg0vOh9g9xSQ+Eu4dznDDl zNVWO3kpaBJfhnWl/62vSDqjTknWTHKpK1+rJMOo1r8V5JEy5MgxOadQcqcz4k+8l2 14AvcZC67LI6QOPM447kP1B8AuBSVSzHqBPsaxjA= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727120AbgHNUKg (ORCPT ); Fri, 14 Aug 2020 16:10:36 -0400 Received: from mail.kernel.org ([198.145.29.99]:49200 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726265AbgHNUKf (ORCPT ); Fri, 14 Aug 2020 16:10:35 -0400 Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 601C2206B2; Fri, 14 Aug 2020 20:10:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597435835; bh=V1LBnLR6GD/H9lBrBNExcAJGbLLMmg8AfmNutpx8vGA=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=XubzUq1kxjyC5SQygeG3LR9yJ8DHHjdN1/M3aSrVHWlCJtG+SSfQyWOM8RzGMwgpa jb0rRWtCr9/lIactA/ZevYNzPnoeK+pl6wOpiQmtcg83y5wcJCcB+zpDmRuuq58m8V oK0vXvWx3EjM51MLhf4amqoc+oh3gST4/TgjbTqY= Date: Fri, 14 Aug 2020 13:10:34 -0700 From: Andrew Morton To: Zhaoyang Huang Cc: Roman Gushchin , Zhaoyang Huang , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm : sync ra->ra_pages with bdi->ra_pages Message-Id: <20200814131034.f71a91c6827904e12a629e04@linux-foundation.org> In-Reply-To: <1597395824-3325-1-git-send-email-zhaoyang.huang@unisoc.com> References: <1597395824-3325-1-git-send-email-zhaoyang.huang@unisoc.com> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.31; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 14 Aug 2020 17:03:44 +0800 Zhaoyang Huang wrote: > Some system(like android) will turbo read during startup via expanding the > readahead window and then set it back to normal(128kb as usual). However, some > files in the system process context will keep to be opened since it is opened > up and has no chance to sync with the updated value as it is almost impossible > to change the files attached to the inode(processes are unaware of these things) How about making VM_READAHEAD_PAGES a variable? Provide a kernel boot parameter to alter the default setting. Userspace can then restore the usual value later in boot?