Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932336Ab0DGIOB (ORCPT ); Wed, 7 Apr 2010 04:14:01 -0400 Received: from mga09.intel.com ([134.134.136.24]:57047 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932115Ab0DGINy (ORCPT ); Wed, 7 Apr 2010 04:13:54 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.51,377,1267430400"; d="scan'208";a="507031835" Date: Wed, 7 Apr 2010 16:13:51 +0800 From: Wu Fengguang To: Minchan Kim Cc: Taras Glek , Johannes Weiner , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" Subject: Re: Downsides to madvise/fadvise(willneed) for application startup Message-ID: <20100407081351.GA20322@localhost> References: <4BBA6776.5060804@mozilla.com> <20100406095135.GB5183@cmpxchg.org> <20100407022456.GA9468@localhost> <4BBBF402.70403@mozilla.com> <20100407071408.GA17892@localhost> <20100407074732.GC17892@localhost> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1137 Lines: 28 Minchan, > A few month ago, I saw your patch about enhancing readahead. > At that time, many guys tested several size of USB and SSD which are > consist of nand device. > The result is good if we does readahead untile some crossover point. > So I think we need readahead about file I/O in non-rotation device, too. > > But startup latency is important than file I/O performance in some machine. > With analysis at that time, code readahead of application affected slow startup. > In addition, during bootup, cache hit ratio was very small. > > So I hoped we can disable readahead just only code section(ie, roughly > exec vma's filemap fault). :) > > I don't want you to solve this problem right now. > Just let you understand embedded system's some problem > for enhancing readahead in future. :) Yeah, I've never heard of such a demand, definitely good to know it! Thanks, Fengguang -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/