Re: 2.7 thoughts

From: William Lee Irwin III <wli@holomorphy.com>
To: Chris Friesen <cfriesen@nortelnetworks.com>
Cc: Mark Mielke <mark@mark.mielke.cc>, G?bor L?n?rt <lgb@lgb.hu>,
	Stuart Longland <stuartl@longlandclan.hopto.org>,
	Stephan von Krawczynski <skraw@ithnet.com>,
	Fabian.Frederick@prov-liege.be, linux-kernel@vger.kernel.org
Subject: Re: 2.7 thoughts
Date: Fri, 10 Oct 2003 09:44:08 -0700	[thread overview]
Message-ID: <20031010164408.GF727@holomorphy.com> (raw)
In-Reply-To: <3F86DFED.2030507@nortelnetworks.com>

Mark Mielke wrote:
>> Note that I didn't say that the software
>> approach could *guarantee* immediate success. You wouldn't unplug the
>> CPU until your had successfully deregistered the CPU from having anything
>> scheduled for it.
>> Is this not the way things (should) work?

On Fri, Oct 10, 2003 at 12:35:57PM -0400, Chris Friesen wrote:
> Note that if you're doing this for high availability purposes, you 
> already need to have some way of handling a cpu that just dies in the 
> middle of processing.  Once you've done that, you can just re-use that 
> to handle hot removal--it just gets treated like a fault.  This is not 
> to say that you can't try and shut it down nicely first, but its not a 
> hard requirement.

If you've lost the registers in-kernel, you can't even get away with
shooting the process. I'm not sure what extreme HA wants to do with
that, but at a such a point it's not really even possible to figure
out how to extract the thing from whatever critical section it may
have been in.

-- wli