Hi I noticed that the xen has support for smp in the xen0 kernel. However once I boot up with it I can only see 1 cpu. I understand this to be that xen0 is a guest within xen, but what does this actully mean, where is xen in realtion to the xen0 kernel? Thanks Shaz _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
> I noticed that the xen has support for smp in the xen0 kernel. However > once I boot up with it I can only see 1 cpu. I understand this to be > that xen0 is a guest within xen, but what does this actully mean, > where is xen in realtion to the xen0 kernel?Xen lives under *everything* in the system. It is responsible for sharing CPU and memory between *all* domains, including dom0. Although dom0 controls IO devices and Xen''s control interface, it''s still Xen itself that sits at the lowest layer and manages sharing. Xen 2.0.x: * Domains (including dom0) can only run on one CPU. * Xen can handle multiple CPUs, so by running multiple domains you can still use all your CPUs. Xen 3.0: * Domains can run on multiple CPUs. This can be more or less than the number of real CPUs. * Dom0 must boot initially on the number of CPUs in the machine, although I believe it can subsequentially relinquish them. * Xen is SMP and responsible for the low-level time sharing of the real CPUs between virtual CPUs running on them. Cheers, Mark _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
On 8/4/05, Mark Williamson <mark.williamson@cl.cam.ac.uk> wrote:> > I noticed that the xen has support for smp in the xen0 kernel. However > > once I boot up with it I can only see 1 cpu. I understand this to be > > that xen0 is a guest within xen, but what does this actully mean, > > where is xen in realtion to the xen0 kernel? > > Xen lives under *everything* in the system. It is responsible for sharing CPU > and memory between *all* domains, including dom0. Although dom0 controls IO > devices and Xen''s control interface, it''s still Xen itself that sits at the > lowest layer and manages sharing. > > Xen 2.0.x: > * Domains (including dom0) can only run on one CPU. > * Xen can handle multiple CPUs, so by running multiple domains you can still > use all your CPUs. > > Xen 3.0: > * Domains can run on multiple CPUs. This can be more or less than the number > of real CPUs. > * Dom0 must boot initially on the number of CPUs in the machine, although I > believe it can subsequentially relinquish them. > * Xen is SMP and responsible for the low-level time sharing of the real CPUs > between virtual CPUs running on them. > > Cheers, > Mark >Thanks for that Mark It''s made things clearer. I''m just writing a simple document about xen and how to install it, and this aspect came up. Looks a lot clearer now. Thanks Shahzad _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users