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Date: Fri, 2 Jan 2004 13:38:37 -0500 (EST)
From: Andre Guibert de Bruet <andy@siliconlandmark.com>
To: Oliver Brandmueller <ob@e-Gitt.NET>
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cc: freebsd-current@freebsd.org
Subject: Re: Hot Swapping CPUs?
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On Fri, 2 Jan 2004, Tom wrote:

> On Fri, 2 Jan 2004, Oliver Brandmueller wrote:
>
> > to the base functionality for CPU hot swapping. One would need (apart
> > from a Motherboard that's able to that ;-)) some control over CPUs now,
> > like disabling a physical CPU during runtime (which could also be done
> > automatically on certain filure onditions).
>
>   sysctl already exposes some variabled to control CPUs on an SMP system.
>
>   It is a pretty hard to detect a CPU failure in software, because the
> software detection will fail at the same time the CPU does.

Right. A hardware watchdog is what's required to effectively check for
fail{ed,ing} cpus. With software, you're left either polling or guessing
that a cpu has gone offline for hardware reasons when it doesn't run
anything on its queue.

> > Is there any work in progress in this direction? Would be a very neat
> > feature for high availability systems.

Find me a x86 motherboard (with specs, preferably) that supports cpu
failure-monitoring and hot-swapping and I'll volunteer time to hack up
some code for you. (We have a need for this functionality in our x86-farm
at work, so I'd get to do it on the clock. :) )

Regards,

> Andre Guibert de Bruet | Enterprise Software Consultant >
> Silicon Landmark, LLC. | http://siliconlandmark.com/    >