From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Tue, 1 Nov 2005 16:01:42 +0100 From: Ingo Molnar Subject: Re: [Lhms-devel] [PATCH 0/7] Fragmentation Avoidance V19 Message-ID: <20051101150142.GA10636@elte.hu> References: <4366A8D1.7020507@yahoo.com.au> <4366C559.5090504@yahoo.com.au> <4366D469.2010202@yahoo.com.au> <20051101135651.GA8502@elte.hu> <1130854224.14475.60.camel@localhost> <20051101142959.GA9272@elte.hu> <1130856555.14475.77.camel@localhost> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1130856555.14475.77.camel@localhost> Sender: owner-linux-mm@kvack.org Return-Path: To: Dave Hansen Cc: Mel Gorman , Nick Piggin , "Martin J. Bligh" , Andrew Morton , kravetz@us.ibm.com, linux-mm , Linux Kernel Mailing List , lhms List-ID: * Dave Hansen wrote: > > then we need to see that 100% solution first - at least in terms of > > conceptual steps. > > I don't think saying "truly 100%" really even makes sense. There will > always be restrictions of some kind. For instance, with a 10MB kernel > image, should you be able to shrink the memory in the system below > 10MB? ;) think of it in terms of filesystem shrinking: yes, obviously you cannot shrink to below the allocated size, but no user expects to be able to do it. But users would not accept filesystem shrinking failing for certain file layouts. In that case we are better off with no ability to shrink: it makes it clear that we have not solved the problem, yet. so it's all about expectations: _could_ you reasonably remove a piece of RAM? Customer will say: "I have stopped all nonessential services, and free RAM is at 90%, still I cannot remove that piece of faulty RAM, fix the kernel!". No reasonable customer will say: "True, I have all RAM used up in mlock()ed sections, but i want to remove some RAM nevertheless". > There is also no precedent in existing UNIXes for a 100% solution. does this have any relevance to the point, other than to prove that it's a hard problem that we should not pretend to be able to solve, without seeing a clear path towards a solution? Ingo -- 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