Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751399AbWBQMTx (ORCPT ); Fri, 17 Feb 2006 07:19:53 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751404AbWBQMTx (ORCPT ); Fri, 17 Feb 2006 07:19:53 -0500 Received: from ebiederm.dsl.xmission.com ([166.70.28.69]:36525 "EHLO ebiederm.dsl.xmission.com") by vger.kernel.org with ESMTP id S1751399AbWBQMTw (ORCPT ); Fri, 17 Feb 2006 07:19:52 -0500 To: Herbert Poetzl Cc: Dave Hansen , "Serge E. Hallyn" , Kirill Korotaev , linux-kernel@vger.kernel.org, vserver@list.linux-vserver.org, Alan Cox , Arjan van de Ven , Suleiman Souhlal , Hubertus Franke , Cedric Le Goater , Kyle Moffett , Greg , Linus Torvalds , Andrew Morton , Greg KH , Rik van Riel , Alexey Kuznetsov , Andrey Savochkin , Kirill Korotaev , Andi Kleen , Benjamin Herrenschmidt , Jeff Garzik , Trond Myklebust , Jes Sorensen Subject: Re: (pspace,pid) vs true pid virtualization References: <20060215145942.GA9274@sergelap.austin.ibm.com> <20060216142928.GA22358@sergelap.austin.ibm.com> <20060216175326.GA11974@sergelap.austin.ibm.com> <20060216184407.GC11974@sergelap.austin.ibm.com> <1140115979.21383.11.camel@localhost.localdomain> <20060217114441.GA17940@MAIL.13thfloor.at> From: ebiederm@xmission.com (Eric W. Biederman) Date: Fri, 17 Feb 2006 05:16:06 -0700 In-Reply-To: <20060217114441.GA17940@MAIL.13thfloor.at> (Herbert Poetzl's message of "Fri, 17 Feb 2006 12:44:41 +0100") Message-ID: User-Agent: Gnus/5.1007 (Gnus v5.10.7) Emacs/21.4 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2863 Lines: 68 Herbert Poetzl writes: > On Fri, Feb 17, 2006 at 03:57:26AM -0700, Eric W. Biederman wrote: >> As for that. When I mad that suggestion to Herbert Poetzl >> his only concern was that a smart init might be too heavy weight >> for lightweight vserver. Generally I like the idea. > > well, may I remind that this solution would require _two_ > init processes for each guest, which could easily make up > 300-400 unnecessary processes in a lightweight server > setup? I take it seriously enough that I remembered the concern, and I think it is legitimate. Figuring out how to safely set the policy is a challenge. That is something a user space daemon trivially gets right. The kernel side of a process is about 10K if the user space side was also lightweight we could have the entire per process cost in the 30K range. 30K*400 = 12000K = 12M. That is significant but we are still cheap enough that it isn't necessarily a show stopper. I think the cost was only one extra process, for the case where you have fakeinit now it would be init, for other cases it would be a daemon that gets setup when you initialize the vserver. If we can get a permission checking model in the kernel right it is potentially much cheaper, to have an enter model. Having user space as a backup to that is still interesting. >> > (Read the last sentence, and in case you're wondering, no I don't have >> > any children in real life) >> >> Speaking of that. One of my coworkers mentioned that it is unfortunate >> that our names don't have the double meaning. So it was suggested we >> call them >> >> Speaking of that problematic naming. One of my coworkers mentioned that >> it is unfortunate that our set of names does not have a double meaning. >> After that the suggestion came up to call them families, instead of guest >> or pidspaces. Although I guess calling them guests is about as bad :) > > well, at least Guests or VEs are terms already used by > existing projects, where pspace sounds somewhat strange. > > at the same time I'd like to point out that *spaces is > a good name for the building blocks, but we definitely > have to name the 'construct' different, i.e. a 'guest' > (or VPS or VE or whatever) is _more_ than just a p-space > it's the sum of all *-spaces required to make it look > like a real linux system. I totally agree. Sorry. This was meant as a humerous tangent! I thought the smiley and the fact I was looking for a name with a double meaning that would have made it easier to get confused would have made that clear! Oh well such is confusion an email :) Eric - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/