From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Jeff Dike Message-ID: <20040410170707.GA6492@ccure.user-mode-linux.org> References: <185d01c41e23$5996cc00$2000000a@schlepptopp> <189201c41e30$d434cc70$2000000a@schlepptopp> <200404091626.i39GQqsf002414@ccure.user-mode-linux.org> <20040410140840.GB5782@ccure.user-mode-linux.org> <4077FDF9.7070707@upb.de> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Disposition: inline In-Reply-To: <4077FDF9.7070707@upb.de> Subject: [uml-devel] Re: [uml-user] Network lags Sender: user-mode-linux-devel-admin@lists.sourceforge.net Errors-To: user-mode-linux-devel-admin@lists.sourceforge.net List-Unsubscribe: , List-Id: The user-mode Linux development list List-Post: List-Help: List-Subscribe: , List-Archive: Date: Sat, 10 Apr 2004 13:07:07 -0400 Content-Transfer-Encoding: quoted-printable To: Sven =?iso-8859-1?Q?K=F6hler?= Cc: user-mode-linux-user@lists.sourceforge.net, user-mode-linux-devel@lists.sourceforge.net On Sat, Apr 10, 2004 at 04:00:25PM +0200, Sven K=F6hler wrote: > what's so bad about it? It can put the host at risk. There's a VM system for a reason, and it needs swap in order to be able to back out of memory shortages. mlocking large amounts of memory subverts that and increases the possibility of deadlockin= g. There are only a few good reasons for mlocking, and performance isn't one of them: when something would break horribly if a page got swapped, i.e. pending DMA or directIO into it security - gpg wants to mlock a page so it can be sure that secrets on it won't be written to disk Those only involve a page at a time, and don't possibly endanger the system. The amounts of mlocked memory you're talking about are so large that they=20 could endanger the system. > well, what do you mean with managing the host memory? will be some kind=20 > tool or built-in option of the UML-kernel? Both. There is pluggable memory in UML, and a tool on the host to manage memory by moving memory between UMLs and between UMLs and the host. So, this daemon would be watching memory use on the host and the UMLs, and if it saw the host running short, it would find an idle UML and take some memory away from it: uml_mconsole config mem=3D-32M This would free the memory to the host, and pull it away from swap. If the host was fine, but another UML was short of memory, it would then give that memory to the busy UML: uml_mconsole config mem+=3D32M Jeff ------------------------------------------------------- This SF.Net email is sponsored by: IBM Linux Tutorials Free Linux tutorial presented by Daniel Robbins, President and CEO of GenToo technologies. Learn everything from fundamentals to system administration.http://ads.osdn.com/?ad_id=1470&alloc_id638&op=CCk _______________________________________________ User-mode-linux-devel mailing list User-mode-linux-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel