From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail172.messagelabs.com (mail172.messagelabs.com [216.82.254.3]) by kanga.kvack.org (Postfix) with SMTP id 507C56B01EE for ; Wed, 7 Apr 2010 04:13:55 -0400 (EDT) Date: Wed, 7 Apr 2010 16:13:51 +0800 From: Wu Fengguang 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: Sender: owner-linux-mm@kvack.org To: Minchan Kim Cc: Taras Glek , Johannes Weiner , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" List-ID: 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, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org