From owner-freebsd-arch@FreeBSD.ORG Mon Oct 11 21:27:51 2004 Return-Path: Delivered-To: freebsd-arch@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id C721D16A4CE for ; Mon, 11 Oct 2004 21:27:51 +0000 (GMT) Received: from mail3.speakeasy.net (mail3.speakeasy.net [216.254.0.203]) by mx1.FreeBSD.org (Postfix) with ESMTP id 9CD5F43D4C for ; Mon, 11 Oct 2004 21:27:51 +0000 (GMT) (envelope-from jhb@FreeBSD.org) Received: (qmail 32560 invoked from network); 11 Oct 2004 21:27:51 -0000 Received: from dsl027-160-063.atl1.dsl.speakeasy.net (HELO server.baldwin.cx) ([216.27.160.63]) (envelope-sender ) encrypted SMTP for ; 11 Oct 2004 21:27:50 -0000 Received: from [10.50.40.210] (gw1.twc.weather.com [216.133.140.1]) (authenticated bits=0) by server.baldwin.cx (8.12.11/8.12.11) with ESMTP id i9BLRH6W042482; Mon, 11 Oct 2004 17:27:47 -0400 (EDT) (envelope-from jhb@FreeBSD.org) From: John Baldwin To: Stephan Uphoff Date: Mon, 11 Oct 2004 16:54:14 -0400 User-Agent: KMail/1.6.2 References: <1095468747.31297.241.camel@palm.tree.com> <20041005130308.GA2586@peter.osted.lan> <1097437808.80398.4.camel@palm.tree.com> In-Reply-To: <1097437808.80398.4.camel@palm.tree.com> MIME-Version: 1.0 Content-Disposition: inline Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <200410111654.14502.jhb@FreeBSD.org> X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on server.baldwin.cx cc: Peter Holm cc: Julian Elischer cc: "freebsd-arch@freebsd.org" Subject: Re: scheduler (sched_4bsd) questions X-BeenThere: freebsd-arch@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Discussion related to FreeBSD architecture List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 11 Oct 2004 21:27:51 -0000 On Sunday 10 October 2004 03:50 pm, Stephan Uphoff wrote: > On Tue, 2004-10-05 at 09:03, Peter Holm wrote: > > On Mon, Oct 04, 2004 at 12:42:53PM -0700, Julian Elischer wrote: > > > > OK, I got a crash dump now, after a few modifications to kern_shutdown.c > > > > There are however a few strange things worth noticing: > > > > 1) The are no panic string: > > > > Mounted root from ufs:/dev/ad0s1a. > > pid 1146: corrected slot count (2->1) > > [thread 100796] > > Stopped at sched_add+0x13: movl 0x14c(%esi),%ebx > > > > 2) The gdb stack trace gets a bit weird at: > > > > #8 0xc07812da in calltrap () at ../../../i386/i386/exception.s:140 > > #9 0xc05f0018 in flock (td=0x0, uap=0x0) at > > ../../../kern/kern_descrip.c:2138 #10 0xc0619fd1 in setrunqueue > > (td=0xc2319180, flags=0x0) at kern_switch.c:521 #11 0xc061921f in > > sched_wakeup (td=0xc2319180) at ../../../kern/sched_4bsd.c:859 > > > > Where did flock() come from? > > > > The full console output is at http://www.holm.cc/stress/log/cons82.html > > > > - Peter > > I am still puzzled. > My newest pet theory is that the sorting of the kg_runq is corrupted > before setrunqueue is called. > Directly changing td_priority while the thread is on the run queue would > be an explanation. > However the only instance that I found is what I think is a rare > condition where sleepq_resume_thread may be called while the thread is > on a runqueue. (John - what did I miss this time ...) This is a good find! > Peter could you try this patch? > > Index: subr_sleepqueue.c > =================================================================== > RCS file: /cvsroot/src/sys/kern/subr_sleepqueue.c,v > retrieving revision 1.11 > diff -u -r1.11 subr_sleepqueue.c > --- subr_sleepqueue.c 19 Aug 2004 11:31:41 -0000 1.11 > +++ subr_sleepqueue.c 10 Oct 2004 18:18:55 -0000 > @@ -642,7 +642,7 @@ > /* Adjust priority if requested. */ > MPASS(pri == -1 || (pri >= PRI_MIN && pri <= PRI_MAX)); > if (pri != -1 && td->td_priority > pri) > - td->td_priority = pri; > + sched_prio(td, pri); > setrunnable(td); > mtx_unlock_spin(&sched_lock); > } > > Should it crash again could you walk the kg_runq to verify the sorting? > > Thanks > Stephan -- John Baldwin <>< http://www.FreeBSD.org/~jhb/ "Power Users Use the Power to Serve" = http://www.FreeBSD.org