From owner-p4-projects@FreeBSD.ORG Tue Oct 26 21:15:43 2004 Return-Path: Delivered-To: p4-projects@freebsd.org Received: by hub.freebsd.org (Postfix, from userid 32767) id 2E4AF16A4EA; Tue, 26 Oct 2004 21:15:43 +0000 (GMT) Delivered-To: perforce@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id CB42916A4CE for ; Tue, 26 Oct 2004 21:15:42 +0000 (GMT) Received: from mail6.speakeasy.net (mail6.speakeasy.net [216.254.0.206]) by mx1.FreeBSD.org (Postfix) with ESMTP id 7839C43D45 for ; Tue, 26 Oct 2004 21:15:42 +0000 (GMT) (envelope-from john@baldwin.cx) Received: (qmail 10921 invoked from network); 26 Oct 2004 21:15:42 -0000 Received: from dsl027-160-063.atl1.dsl.speakeasy.net (HELO server.baldwin.cx) ([216.27.160.63]) (envelope-sender ) encrypted SMTP for ; 26 Oct 2004 21:15:41 -0000 Received: from zion.baldwin.cx (zion.baldwin.cx [192.168.0.7]) by server.baldwin.cx (8.12.11/8.12.11) with ESMTP id i9QLFcqw009558; Tue, 26 Oct 2004 17:15:38 -0400 (EDT) (envelope-from john@baldwin.cx) Received: from zion.baldwin.cx (localhost [127.0.0.1]) by zion.baldwin.cx (8.12.10/8.12.10) with ESMTP id i9QLFc8h015284; Tue, 26 Oct 2004 17:15:38 -0400 (EDT) (envelope-from john@zion.baldwin.cx) Received: from localhost (localhost [[UNIX: localhost]]) by zion.baldwin.cx (8.12.10/8.12.10/Submit) id i9QLFbLF015283; Tue, 26 Oct 2004 17:15:37 -0400 (EDT) (envelope-from john) From: John Baldwin To: Brian Fundakowski Feldman Date: Tue, 26 Oct 2004 16:51:19 -0400 User-Agent: KMail/1.6 References: <200410192159.i9JLxNLE003024@repoman.freebsd.org> <200410201258.26325.jhb@FreeBSD.org> <20041022033700.GL1072@green.homeunix.org> In-Reply-To: <20041022033700.GL1072@green.homeunix.org> MIME-Version: 1.0 Content-Disposition: inline Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <200410261651.19567.jhb@FreeBSD.org> X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on server.baldwin.cx cc: Perforce Change Reviews cc: Julian Elischer Subject: Re: PERFORCE change 63396 for review X-BeenThere: p4-projects@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: p4 projects tree changes List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 26 Oct 2004 21:15:43 -0000 On Thursday 21 October 2004 11:37 pm, Brian Fundakowski Feldman wrote: > On Wed, Oct 20, 2004 at 12:58:26PM -0400, John Baldwin wrote: > > On Tuesday 19 October 2004 06:19 pm, Julian Elischer wrote: > > > John Baldwin wrote: > > > >http://perforce.freebsd.org/chv.cgi?CH=63396 > > > > > > > >Change 63396 by jhb@jhb_tibook on 2004/10/19 21:58:24 > > > > > > > > Update. > > > > > > > >Affected files ... > > > > > > > >.. //depot/projects/smpng/sys/notes#21 edit > > > > > > > >Differences ... > > > > > > > >==== //depot/projects/smpng/sys/notes#21 (text+ko) ==== > > > > > > > >@@ -33,6 +33,10 @@ > > > > - Untested > > > > - Don't allow kthreads to get signalled and do bad things > > > > - Untested > > > >+- Change amd64 to use [ls]fence instructions for memory barriers. > > > >+ - Untested (and no hardware, maybe peter can test) > > > >+- Turn off the ipiwakeups in 4BSD since the currently implementation > > > > can + lead to IPI deadlocks > > > > > > the implementation of IPIs or the implementation of IPIwakeup? > > > > Kind of hard to say. The problem is if a CPU tries to send two IPI_AST's > > without enabling interrupts in between. The first IPI may not be > > delivered when the second one is requested because the target of the > > first IPI has interrupts disabled for some reason (doing a TLB shootdown > > is the worst case scenario). The other CPU won't enable interrupts to > > allow the first AST until it's shootdown is acknowledged. Since the > > first IPI is never delivered, then the second IPI attempt will never be > > able to deliver an IPI, resulting in either a panic or deadlock. My quad > > xeon is highly unstable on HEAD, btw, and this does seem to help it. > > Isn't this what I said a few weeks ago was probably the problem? I have no idea, but ups@ brought this up a couple of weeks ago when we met for lunch. -- John Baldwin <>< http://www.FreeBSD.org/~jhb/ "Power Users Use the Power to Serve!" - http://www.FreeBSD.org/