Cache coherency, clustering, and Kernel virtualization

[Matthew Dillon]

:On Sat, Sep 02, 2006 at 11:49:36AM -0700, Matthew Dillon wrote:
:>     Sounds kinda like what IBM did with linux on its mainframes, eh?  But I
:>     am going to do it with DragonFly and my expectation is that performance
:>     within a virtual kernel will be within 20% of the performance of a
:>     real kernel.
:
:And why reinvent the wheel? Xen is providing exactly that -- light
:weight virtualisation similiar to what IBM provided in hardware.
:It has the big advantage of being proven technology and does support
:multiple kernel already.
:
:Performance numbers are available as well, depending on usage pattern
:the impact is quite low.
:
:Joerg

    Xen is the one that runs a linux kernel as the primary OS?  I really
    have no desire to make DragonFly dependant on some other OS for 
    features.  And, frankly, I'm not sure I would consider Xen to be
    contemporary to an actual native user-mode kernel.  They are two very
    different beasts, with very different levels of integration.  Just
    because it is a virtualization technology doesn't mean it is the
    right virtualization technology for us.

    I don't want DragonFly to get into the code bloat rut, where making
    a feature work requires bringing together several huge and distinct
    projects and then praying that they don't become incompatible with
    each other over time.

					-Matt
					Matthew Dillon 
					<dillon at xxxxxxxxxxxxx>