From owner-p4-projects@FreeBSD.ORG Fri Oct 22 03:37:06 2004 Return-Path: Delivered-To: p4-projects@freebsd.org Received: by hub.freebsd.org (Postfix, from userid 32767) id 7893616A4D0; Fri, 22 Oct 2004 03:37:06 +0000 (GMT) Delivered-To: perforce@freebsd.org Received: from green.homeunix.org (freefall.freebsd.org [216.136.204.21]) by hub.freebsd.org (Postfix) with ESMTP id E41BD16A4CE; Fri, 22 Oct 2004 03:37:05 +0000 (GMT) Received: from green.homeunix.org (green@localhost [127.0.0.1]) by green.homeunix.org (8.13.1/8.13.1) with ESMTP id i9M3b5bt079820; Thu, 21 Oct 2004 23:37:05 -0400 (EDT) (envelope-from green@green.homeunix.org) Received: (from green@localhost) by green.homeunix.org (8.13.1/8.13.1/Submit) id i9M3b0ph079819; Thu, 21 Oct 2004 23:37:00 -0400 (EDT) (envelope-from green) Date: Thu, 21 Oct 2004 23:37:00 -0400 From: Brian Fundakowski Feldman To: John Baldwin Message-ID: <20041022033700.GL1072@green.homeunix.org> References: <200410192159.i9JLxNLE003024@repoman.freebsd.org> <417592DB.6050609@elischer.org> <200410201258.26325.jhb@FreeBSD.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200410201258.26325.jhb@FreeBSD.org> User-Agent: Mutt/1.5.6i 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: Fri, 22 Oct 2004 03:37:07 -0000 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? -- Brian Fundakowski Feldman \'[ FreeBSD ]''''''''''\ <> green@FreeBSD.org \ The Power to Serve! \ Opinions expressed are my own. \,,,,,,,,,,,,,,,,,,,,,,\