Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750751AbWBIUCw (ORCPT ); Thu, 9 Feb 2006 15:02:52 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750754AbWBIUCw (ORCPT ); Thu, 9 Feb 2006 15:02:52 -0500 Received: from mustang.oldcity.dca.net ([216.158.38.3]:11955 "HELO mustang.oldcity.dca.net") by vger.kernel.org with SMTP id S1750751AbWBIUCv (ORCPT ); Thu, 9 Feb 2006 15:02:51 -0500 Subject: Re: preempt-rt, NUMA and strange latency traces From: Lee Revell To: =?ISO-8859-1?Q?S=E9bastien_Dugu=E9?= Cc: Steven Rostedt , "linux-kernel@vger.kernel.org" , Ingo Molnar In-Reply-To: <1139484275.5706.19.camel@frecb000686> References: <1139311689.19708.36.camel@frecb000686> <1139395534.21471.13.camel@frecb000686> <1139465045.30058.31.camel@mindpipe> <1139484275.5706.19.camel@frecb000686> Content-Type: text/plain; charset=ISO-8859-1 Date: Thu, 09 Feb 2006 15:02:44 -0500 Message-Id: <1139515365.30058.91.camel@mindpipe> Mime-Version: 1.0 X-Mailer: Evolution 2.5.90 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1244 Lines: 30 On Thu, 2006-02-09 at 12:24 +0100, S?bastien Dugu? wrote: > On Thu, 2006-02-09 at 01:04 -0500, Lee Revell wrote: > > On Wed, 2006-02-08 at 11:45 +0100, S?bastien Dugu? wrote: > > > The more I think about it, the more I tend to believe it's hardware > > > related. It seems as if the CPU just hangs for ~27 ms before > > > resuming processing. > > > > That would be an exceptionally long latency - you would probably notice > > it if the mouse froze, VOIP dropped out, ping stops, etc for 30ms. > > > > It's a test machine and I use it remotely with console redirected so > no mouse, no RT applications aside from my silly nanosleep() loop. But > I do notice that that test sometimes takes more time (ie when I get > those weird latencies). Argh. You would think the vendors would consider a 30ms delay unacceptable. This is big enough to show up on an MRTG graph of ping times ferchrissake. I guess the assumption is that most hardware will never be used for even soft RT work... Lee - 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/