From owner-freebsd-current@FreeBSD.ORG Mon Jul 12 20:39:44 2004 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 4E6AC16A4CE for ; Mon, 12 Jul 2004 20:39:44 +0000 (GMT) Received: from fledge.watson.org (fledge.watson.org [204.156.12.50]) by mx1.FreeBSD.org (Postfix) with ESMTP id ED94343D3F for ; Mon, 12 Jul 2004 20:39:43 +0000 (GMT) (envelope-from robert@fledge.watson.org) Received: from fledge.watson.org (localhost [127.0.0.1]) by fledge.watson.org (8.12.11/8.12.11) with ESMTP id i6CKdO1O053264; Mon, 12 Jul 2004 16:39:24 -0400 (EDT) (envelope-from robert@fledge.watson.org) Received: from localhost (robert@localhost)i6CKdO3d053261; Mon, 12 Jul 2004 16:39:24 -0400 (EDT) (envelope-from robert@fledge.watson.org) Date: Mon, 12 Jul 2004 16:39:24 -0400 (EDT) From: Robert Watson X-Sender: robert@fledge.watson.org To: Johan Pettersson In-Reply-To: <20040712223557.095e8b1c.manlix@demonized.net> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII cc: freebsd-current@freebsd.org cc: avleeuwen@piwebs.com cc: skywizard@mybsd.org.my Subject: Re: Native preemption is the culprit [was Re: today's CURRENT lockups] X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 12 Jul 2004 20:39:44 -0000 On Mon, 12 Jul 2004, Johan Pettersson wrote: > > Per my earlier post, I've experienced similar unreliability. The work > > around I'm using is to build with "#define PREEMPTION" from param.h > > disabled. This results in a quite usable kernel, although quite > > probably more poor interrupt handling latency, etc. > > Do you or John or any one else know whats can cause this? Is there any > ongoing work to fix this? It's not currently clear what the cause is -- reports suggest that it's an existing bug that's getting triggered by preemption, although I wouldn't rule out a bug in the preemption implementation itself. I'm currently setting up a box with NMI to see if I can get some more useful information, as serial break isn't cutting it (suggesting a leaked spin lock or critical section). I don't have an ETA, but I'm guessing that we'll have some sort of resolution in the next day or two. If not, I guess we back out the change, or disable PREEMPTION by default. Robert N M Watson FreeBSD Core Team, TrustedBSD Projects robert@fledge.watson.org Principal Research Scientist, McAfee Research