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Date: Thu, 6 Dec 2001 11:53:38 -0800
From: Larry McVoy <lm@bitmover.com>
To: Daniel Phillips <phillips@bonn-fries.net>
Cc: Larry McVoy <lm@bitmover.com>, "David S. Miller" <davem@redhat.com>,
        davidel@xmailserver.org, rusty@rustcorp.com.au,
        Martin.Bligh@us.ibm.com, riel@conectiva.com.br, lars.spam@nocrew.org,
        alan@lxorguk.ukuu.org.uk, hps@intermeta.de,
        linux-kernel@vger.kernel.org
Subject: Re: SMP/cc Cluster description
Message-ID: <20011206115338.E27589@work.bitmover.com>
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In-Reply-To: <E16C4PM-0000qu-00@starship.berlin>; from phillips@bonn-fries.net on Thu, Dec 06, 2001 at 08:42:05PM +0100
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On Thu, Dec 06, 2001 at 08:42:05PM +0100, Daniel Phillips wrote:
> On December 6, 2001 09:02 am, Larry McVoy wrote:
> > On Wed, Dec 05, 2001 at 11:56:17PM -0800, David S. Miller wrote:
> > > These lockless algorithms, instructions like CAS, DCAS, "infinite
> > > consensus number", it's all crap.  You have to seperate out the access
> > > areas amongst different cpus so they don't collide, and none of these
> > > mechanisms do that.
> > 
> > Err, Dave, that's *exactly* the point of the ccCluster stuff.  You get
> > all that seperation for every data structure for free.  Think about
> > it a bit.  Aren't you going to feel a little bit stupid if you do all
> > this work, one object at a time, and someone can come along and do the
> > whole OS in one swoop?  Yeah, I'm spouting crap, it isn't that easy,
> > but it is much easier than the route you are taking.  
> 
> What I don't get after looking at your material, is how you intend to do the 
> locking.  Sharing a mmap across OS instances is fine, but how do processes on 
> the two different OS's avoid stepping on each other when they access the same 
> file?

Exactly the same way they would if they were two processes on a traditional
SMP OS.
-- 
---
Larry McVoy            	 lm at bitmover.com           http://www.bitmover.com/lm 
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