From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx175.postini.com [74.125.245.175]) by kanga.kvack.org (Postfix) with SMTP id 8C9996B005D for ; Tue, 15 Jan 2013 19:09:59 -0500 (EST) Date: Tue, 15 Jan 2013 16:09:57 -0800 From: Andrew Morton Subject: Re: [PATCH 2/2] mm: forcely swapout when we are out of page cache Message-Id: <20130115160957.9ef860d7.akpm@linux-foundation.org> In-Reply-To: <20130111044327.GB6183@blaptop> References: <1357712474-27595-1-git-send-email-minchan@kernel.org> <1357712474-27595-3-git-send-email-minchan@kernel.org> <20130109162602.53a60e77.akpm@linux-foundation.org> <20130110022306.GB14685@blaptop> <20130110135828.c88bcaf1.akpm@linux-foundation.org> <20130111044327.GB6183@blaptop> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Minchan Kim Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Dan Magenheimer , Sonny Rao , Bryan Freed , Hugh Dickins , Rik van Riel , Johannes Weiner On Fri, 11 Jan 2013 13:43:27 +0900 Minchan Kim wrote: > Hi Andrew, > > On Thu, Jan 10, 2013 at 01:58:28PM -0800, Andrew Morton wrote: > > On Thu, 10 Jan 2013 11:23:06 +0900 > > Minchan Kim wrote: > > > > > > I have a feeling that laptop mode has bitrotted and these patches are > > > > kinda hacking around as-yet-not-understood failures... > > > > > > Absolutely, this patch is last guard for unexpectable behavior. > > > As I mentioned in cover-letter, Luigi's problem could be solved either [1/2] > > > or [2/2] but I wanted to add this as last resort in case of unexpected > > > emergency. But you're right. It's not good to hide the problem like this path > > > so let's drop [2/2]. > > > > > > Also, I absolutely agree it has bitrotted so for correcting it, we need a > > > volunteer who have to inverstigate power saveing experiment with long time. > > > So [1/2] would be band-aid until that. > > > > I'm inclined to hold off on 1/2 as well, really. > > Then, what's your plan? My plan is to sit here until someone gets down and fully tests and fixes laptop-mode. Making it work properly, reliably and as-designed. Or perhaps someone wants to make the case that we just don't need it any more (SSDs are silent!) and removes it all. > > > > The point of laptop_mode isn't to save power btw - it is to minimise > > the frequency with which the disk drive is spun up. By deferring and > > then batching writeout operations, basically. > > I don't get it. Why should we minimise such frequency? Because my laptop was going clickety every minute and was keeping me awake. > It's for saving the power to increase batter life. It might well have that effect, dunno. That wasn't my intent. Testing needed! > As I real all document about laptop_mode, they all said about the power > or battery life saving. > > 1. Documentation/laptops/laptop-mode.txt > 2. http://linux.die.net/man/8/laptop_mode > 3. http://samwel.tk/laptop_mode/ > 3. http://www.thinkwiki.org/wiki/Laptop-mode Documentation creep ;) Ten years ago, gad: http://lwn.net/Articles/1652/ -- 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