Re: [Xen-devel] Re: [ANNOUNCE] Xen high-performance x86 virtualization

[Karim Yaghmour <karim@opersys.com>]

Keir Fraser wrote:
> Full recursion needs full virtualization. Our approach offers much
> better performance in the situations where full virtualization isn't
> required -- i.e., where it's feasible to distribute a ported OS.

I noticed that the SOSP Xen paper briefly mentions Jacques Gelinas' work
on VServers (http://www.solucorp.qc.ca/miscprj/s_context.hc). While
Jacques' work hasn't attracted as much public attention as other Linux
virtualization efforts, I've personally found the approach and concepts
quite fascinating. Among other things, most of the code implementing the
contexts is architecture-independent (save for a few syscalls added to
arch/*/kernel/entry.S). So, thinking aloud here, I'm wondering in what
circumstances I'd prefer using something as architecture specific as
Xen over something as architecture independent as Jacques' VServers?
(Granted VServers can't run Windows, but I'm asking this from the angle
of people looking for resource isolation in the Linux context.) Among
other things, VServers are already in use by many ISPs to provide
simultaneous hosting of many "virtual machines" on the same box while
maintaining strict separation between machines and still providing a
secure environment.

Karim

P.S.:
For those who aren't familiar with Jacques' stuff, have a look at this
document here:
http://www.solucorp.qc.ca/miscprj/s_context.hc?prjstate=1&nodoc=0
The actual concepts implemented in VServers are here:
http://www.solucorp.qc.ca/miscprj/s_context.hc?s1=2&s2=0&s3=0&s4=0&full=0&prjstate=1&nodoc=0
-- 
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Pushing Embedded and Real-Time Linux Systems Beyond the Limits
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