Re: SMP/cc Cluster description

Larry McVoy
2001-12-06T23:15:34Z

On Thu, Dec 06, 2001 at 10:55:37PM +0000, Alan Cox wrote:
> > > ftruncate
> >
> > I'm not sure what the point is. We've already agreed that the multiple OS
> > instances will have synchonization to do for file operations, ftruncate
> > being one of them.
> >
> > I thought the question was how N user processes do locking and my answer
> > stands: exactly like they'd do it on an SMP, with mutex_enter()/exit() on
> > some portion of the mapped file. The mapped file is just a chunk of cache
>
> ftrucate invalidates that memory under you, on all nodes. That means you do
> end up needing cross node locking and your file operations simply won't lie
> down and scale cleanly

Wait a second, you're missing something. If you are going to make a single
OS image work on a 64 way (or whatever) SMP, you have all of these issues,
right? I'm not introducing additional locking problems with the design.
--
---
Larry McVoy lm at bitmover.com http://www.bitmover.com/lm