Re: [patch] SMP alternatives

From: Andi Kleen
Date: Wed Nov 23 2005 - 17:22:59 EST

On Wed, Nov 23, 2005 at 02:15:24PM -0800, Linus Torvalds wrote:
> On Wed, 23 Nov 2005, Andi Kleen wrote:
> >
> > > THAT is what I'd like to have CPU support for. Not for UP (it's going
> > > away), and not for the kernel (it's never single-threaded).
> >
> > There is one reasonly interesting special case that will probably stay
> > around: single CPU guest in a virtualized environment.
> .. and then the _virtualizer_ should just set the bit.

That wouldn't work if it's limited limited to ring 3.

Also currently at least the Xen the driver interfaces seem to
rely on lock, but perhaps that can be changed.

> However, quite frankly, virtualization is overhyped, in my opinion. And if
> it forces people to run UP because of performance issues, it's simply not
> acceptable for a lot of loads.

I don't think it'll force them to that, it will just be a common
use case. e.g. you start a separate VM to run your firewall in.
Do you really need it multithreaded?


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