From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261436AbVFJXTV (ORCPT ); Fri, 10 Jun 2005 19:19:21 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261410AbVFJXS6 (ORCPT ); Fri, 10 Jun 2005 19:18:58 -0400 Received: from e35.co.us.ibm.com ([32.97.110.133]:31376 "EHLO e35.co.us.ibm.com") by vger.kernel.org with ESMTP id S261436AbVFJXQZ (ORCPT ); Fri, 10 Jun 2005 19:16:25 -0400 Date: Fri, 10 Jun 2005 16:16:47 -0700 From: "Paul E. McKenney" To: Lee Revell Cc: Andrea Arcangeli , Tim Bird , linux-kernel@vger.kernel.org, bhuey@lnxw.com, tglx@linutronix.de, karim@opersys.com, mingo@elte.hu, pmarques@grupopie.com, bruce@andrew.cmu.edu, nickpiggin@yahoo.com.au, ak@muc.de, sdietrich@mvista.com, dwalker@mvista.com, hch@infradead.org, akpm@osdl.org Subject: Re: Attempted summary of "RT patch acceptance" thread Message-ID: <20050610231647.GK1300@us.ibm.com> Reply-To: paulmck@us.ibm.com References: <20050608022646.GA3158@us.ibm.com> <42A8D1F3.8070408@am.sony.com> <20050609235026.GE1297@us.ibm.com> <1118372388.32270.6.camel@mindpipe> <20050610154745.GA1300@us.ibm.com> <20050610173728.GA6564@g5.random> <1118436338.6423.48.camel@mindpipe> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1118436338.6423.48.camel@mindpipe> User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jun 10, 2005 at 04:45:38PM -0400, Lee Revell wrote: > On Fri, 2005-06-10 at 19:37 +0200, Andrea Arcangeli wrote: > > You don't need to add it to the document, but as a further pratical > > example of troublesome hardware besides VGA (could be a software issue > > and not hardware issue though) > > The VGA problems were due to (X, not kernel!) driver bugs. Recent > versions of X are thought to be OK. > > It's the exact same issue described in this paper, scroll down to > section 4.5. > > http://www.cs.utah.edu/~regehr/papers/hotos7/hotos7.html > > There's absolutely nothing the kernel or PREEMPT_RT can do about this, > AFAICT even RTAI would be affected, because X lets userspace drivers > talk directly to the hardware including wedging the PCI bus. Cute! I suppose that Eric Piel's approach would avoid this problem if implemented on a NUMA machine with all processes making use of video being affinitied to the NUMA node containing the video card. ;-) Sounds like I need to add "antisocial hardware" to the list of things that need to be inspected to validate realtime latencies. Thanx, Paul