From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ingo Molnar Subject: Re: [PATCH 5/5 V2] kvm tools: Initialize and use VESA and VNC Date: Tue, 24 May 2011 21:03:56 +0200 Message-ID: <20110524190356.GD6561@elte.hu> References: <20110524085024.GA31453@elte.hu> <4DDB75EC.7000300@redhat.com> <4DDB9510.8030501@redhat.com> <4DDB96CA.1030206@redhat.com> <4DDB9972.5050501@redhat.com> <4DDBC28E.8080009@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Avi Kivity , Paolo Bonzini , Sasha Levin , john@jfloren.net, kvm@vger.kernel.org, asias.hejun@gmail.com, gorcunov@gmail.com, prasadjoshi124@gmail.com To: Pekka Enberg Return-path: Received: from mx3.mail.elte.hu ([157.181.1.138]:46523 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756246Ab1EXTEE (ORCPT ); Tue, 24 May 2011 15:04:04 -0400 Content-Disposition: inline In-Reply-To: Sender: kvm-owner@vger.kernel.org List-ID: * Pekka Enberg wrote: > As for the specific issues you mention, only RCU and locking mechanisms seem > like something that are not trivial to port (although userspace RCU already > exists). Indeed. > [ Porting lockdep to userspace would be one cool feature, though. ] Agreed - we already ran into a few locking bugs that were IMO needlessly difficult to debug - our expectations got spoiled by lockdep i guess! :-) Porting RCU would also have its distinct advantages in terms of scalability. While tools/perf/ probably wont need it (all its scalability-relevant code runs in the kernel), tools/kvm/ definitely looks like a candidate for good user-space RCU primitives. > On Tue, May 24, 2011 at 5:37 PM, Avi Kivity wrote: > > It's a lot easier to use the native userspace stacks. > > We will be using userspace libs where appropriate (like with libvnc). We are using a fair amount of userspace libraries in perf too: -ldw, -lelf, -lnewt, -lslang, we used -laudit too for some time. Thanks, Ingo