From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S267413AbUHZE3j (ORCPT ); Thu, 26 Aug 2004 00:29:39 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S267460AbUHZE3j (ORCPT ); Thu, 26 Aug 2004 00:29:39 -0400 Received: from parcelfarce.linux.theplanet.co.uk ([195.92.249.252]:418 "EHLO www.linux.org.uk") by vger.kernel.org with ESMTP id S267413AbUHZE3h (ORCPT ); Thu, 26 Aug 2004 00:29:37 -0400 Date: Thu, 26 Aug 2004 05:29:36 +0100 From: viro@parcelfarce.linux.theplanet.co.uk To: Kyle Moffett Cc: Chris Wright , LKML , Rik van Riel , Tim Hockin , Mike Waychison , ReiserFS List , Hans Reiser Subject: Re: Using fs views to isolate untrusted processes: I need an assistant architect in the USA for Phase I of a DARPA funded linux kernel project Message-ID: <20040826042936.GR21964@parcelfarce.linux.theplanet.co.uk> References: <410D96DC.1060405@namesys.com> <20040825205618.GA7992@hockin.org> <30958D95-F6ED-11D8-A7C9-000393ACC76E@mac.com> <412D2BD2.2090408@sun.com> <20040825180615.Z1973@build.pdx.osdl.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Aug 26, 2004 at 12:16:43AM -0400, Kyle Moffett wrote: > I'm well aware of the technique, but I was wondering if there was any > extra VFS baggage associated with a normal bind mount that might > be eliminated by restricting a different version of a bind mount to only > files. That's why I asked later if anybody had benchmarked the bind > mount system to see how well it would scale to 1000 bound files and > directories. If it's not a performance issue then I really don't care > less, > but I have a somewhat old box that must make do as a fileserver, so > I'm very interested in maximizing the performance. I don't care much > about extra RAM consumption, only about CPU and bus usage. Files and directories are not different in that respect - the only overhead is price of hash lookup when crossing the binding in either case. 1000 bindings shouldn't be a problem - it's 3--5 per hash chain. Wrt memory, it's one struct vfsmount allocated per binding - IOW, about 80Kb total for 1000 of those.