From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Thu, 3 Nov 2005 20:52:02 -0800 From: Andrew Morton Subject: Re: [Lhms-devel] [PATCH 0/7] Fragmentation Avoidance V19 Message-Id: <20051103205202.4417acf4.akpm@osdl.org> In-Reply-To: <1131035000.24503.135.camel@localhost.localdomain> References: <200511021747.45599.rob@landley.net> <43699573.4070301@yahoo.com.au> <200511030007.34285.rob@landley.net> <20051103163555.GA4174@ccure.user-mode-linux.org> <1131035000.24503.135.camel@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Badari Pulavarty Cc: jdike@addtoit.com, rob@landley.net, nickpiggin@yahoo.com.au, gh@us.ibm.com, mingo@elte.hu, kamezawa.hiroyu@jp.fujitsu.com, haveblue@us.ibm.com, mel@csn.ul.ie, mbligh@mbligh.org, kravetz@us.ibm.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, lhms-devel@lists.sourceforge.net List-ID: Badari Pulavarty wrote: > > > With Badari's patch and UML memory hotplug, the infrastructure is > > there to make this work. The one thing I'm puzzling over right now is > > how to measure memory pressure. > > Yep. This is the exactly the issue other product groups normally raise > on Linux. How do we measure memory pressure in linux ? Some of our > software products want to grow or shrink their memory usage depending > on the memory pressure in the system. Since most memory is used for > cache, "free" really doesn't indicate anything -they are monitoring > info in /proc/meminfo and swapping rates to "guess" on the memory > pressure. They want a clear way of finding out "how badly" system > is under memory pressure. (As a starting point, they want to find out > out of "cached" memory - how much is really easily "reclaimable" > under memory pressure - without swapping). I know this is kind of > crazy, but interesting to think about :) Similarly, that SGI patch which was rejected 6-12 months ago to kill off processes once they started swapping. We thought that it could be done from userspace, but we need a way for userspace to detect when a task is being swapped on a per-task basis. I'm thinking a few numbers in the mm_struct, incremented in the pageout code, reported via /proc/stat. -- 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