From owner-freebsd-threads@FreeBSD.ORG Sun Nov 16 12:56:18 2003 Return-Path: Delivered-To: freebsd-threads@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id DF91616A4CE; Sun, 16 Nov 2003 12:56:18 -0800 (PST) Received: from ns1.xcllnt.net (209-128-86-226.BAYAREA.NET [209.128.86.226]) by mx1.FreeBSD.org (Postfix) with ESMTP id 6B98A43F93; Sun, 16 Nov 2003 12:56:17 -0800 (PST) (envelope-from marcel@xcllnt.net) Received: from dhcp01.pn.xcllnt.net (dhcp01.pn.xcllnt.net [192.168.4.201]) by ns1.xcllnt.net (8.12.9/8.12.9) with ESMTP id hAGKuHbe052191; Sun, 16 Nov 2003 12:56:17 -0800 (PST) (envelope-from marcel@piii.pn.xcllnt.net) Received: from dhcp01.pn.xcllnt.net (localhost [127.0.0.1]) hAGKuGbH061043; Sun, 16 Nov 2003 12:56:16 -0800 (PST) (envelope-from marcel@dhcp01.pn.xcllnt.net) Received: (from marcel@localhost) by dhcp01.pn.xcllnt.net (8.12.10/8.12.10/Submit) id hAGKuG83061042; Sun, 16 Nov 2003 12:56:16 -0800 (PST) (envelope-from marcel) Date: Sun, 16 Nov 2003 12:56:16 -0800 From: Marcel Moolenaar To: Daniel Eischen Message-ID: <20031116205616.GB60888@dhcp01.pn.xcllnt.net> References: <20031116195342.GA60773@dhcp01.pn.xcllnt.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.4i cc: threads@freebsd.org cc: davidxu@freebsd.org Subject: Re: KSE/ia64 broken X-BeenThere: freebsd-threads@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Threading on FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 16 Nov 2003 20:56:19 -0000 On Sun, Nov 16, 2003 at 03:09:14PM -0500, Daniel Eischen wrote: > On Sun, 16 Nov 2003, Marcel Moolenaar wrote: > > On Sun, Nov 16, 2003 at 02:30:20PM -0500, Daniel Eischen wrote: > > > > > What should I be looking at, [um]c_flags? > > > > mc_flags is very informative. > > > > > $ simple > > > Found completed thread 6000000000014000, uc_flags 0x0, mc_flags 0x8, name initial thread > > > > This is a context created by the kernel. It's one created by getcontext(). > > I'm not sure what you mean by "created by getcontext()". You > mean get_mcontext(), the syscall getcontext(), or userland > _ia64_save_context()? It shouldn't be from the syscall getcontext() > because it is the initial thread. I meant getcontext(2). _ia64_save_context() always creates contexts that have mc_flags=0. Note that all synchronuous contexts created by the kernel have valid return registers. It's not only getcontext(2) that does that. I was sloppy. The context could be the result of an upcall due to a blocking system call. > > Only the kernel needs to preserve the return registers (which is what > > mc_flags indicates) because it needs to be able to resume system calls. > > > > > Switching out thread 6000000000014000, state 0 > > > Threads in waiting queue: > > > Found completed thread 6000000000014000, uc_flags 0x0, mc_flags 0x3, name initial thread > > > > This is an asynchronuous context. Probably the result of a trap, but > > possibly the result of an interrupt. Does this mean that the thread > > has run since it was last found (i.e. the previous context) or do we > > have a case where a context is clobbered (I don't see a switch in)? > > Yes, this is the main thread and has run, blocked, and now completed. > All three statements above are from the KSE scheduler as a result of > an upcall. See my comment above. > The same thread (main thread) is being resumed over and over again > which shouldn't happen for this simple program. Can it be that the thread is deadlocked? There's no forward progress. There's only context switching... -- Marcel Moolenaar USPA: A-39004 marcel@xcllnt.net