Date: Tue, 26 Oct 2004 17:07:09 -0400 From: John Baldwin <jhb@FreeBSD.org> To: Stephan Uphoff <ups@tree.com> Cc: freebsd-current@FreeBSD.org Subject: Re: number of CPUs and IPI panic Message-ID: <200410261707.09293.jhb@FreeBSD.org> In-Reply-To: <1098811105.20390.16988.camel@palm.tree.com> References: <20041020221659.33824.qmail@web21124.mail.yahoo.com> <200410211705.45147.jhb@FreeBSD.org> <1098811105.20390.16988.camel@palm.tree.com>
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On Tuesday 26 October 2004 01:18 pm, Stephan Uphoff wrote: > On Thu, 2004-10-21 at 17:05, John Baldwin wrote: > > On Wednesday 20 October 2004 09:05 pm, Stephan Uphoff wrote: > > > Can you try the attached patch? > > > ( Hope it still applies since it is a few weeks old) > > > > > > If this does not work I have a few more questions next week. > > > > Unfortunately it can enable interrupts with sched_lock held which can > > result in deadlocks due to ithread preemption (IIRC, maybe not as badly > > with the newer preemption code.) > > The code only enables interrupts for TLB shootdowns. > In this case it is guaranteed that it holds the smp_ipi_mtx that as a > side effect protects it against preemption and holds no other spin > mutex. > I don't see the problem. I must have missed the TLB shootdown detail then when I looked over it. We send some other IPI's such as IPI_AST while holding sched_lock and if we enabled interrupts during that we could have problems. > I am thinking about implementing the bitmap based stuff be talked about > a few weeks ago to avoid having more than one queued IPI of the same > type. -- John Baldwin <jhb@FreeBSD.org> <>< http://www.FreeBSD.org/~jhb/ "Power Users Use the Power to Serve!" - http://www.FreeBSD.org/
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