[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-users] Re: Xen is a feature
* Avi Kivity <avi@xxxxxxxxxx> wrote: > Ingo Molnar wrote: >>> There is in fact a way to get dom0 support with nearly no changes to >>> Linux, but it involves massive changes to Xen itself and requires >>> hardware support: run dom0 as a fully virtualized guest, and assign >>> it all the resources dom0 can access. It's probably a massive effort >>> though. >>> >>> I've considered it for kvm when faced with the "I want a thin >>> hypervisor" question: compile the hypervisor kernel with PCI support >>> but nothing else (no CONFIG_BLOCK or CONFIG_NET, no device drivers), >>> load userspace from initramfs, and assign host devices to one or more >>> privileged guests. You could probably run the host with a heavily >>> stripped configuration, and enjoy the slimness while every interrupt >>> invokes the scheduler, a context switch, and maybe an IPI for good >>> measure. >>> >> >> This would be an acceptable model i suspect, if someone wants a 'slim >> hypervisor'. >> >> We can context switch way faster than we handle IRQs. Plus in a >> slimmed-down config we could intentionally slim down aspects of the >> scheduler as well, if it ever became a measurable performance issue. >> The hypervisor would run a minimal user-space and most of the >> context-switching overhead relates to having a full-fledged user-space >> with rich requirements. So there's no real conceptual friction between >> a 'lean and mean' hypervisor and a full-featured native kernel. >> > > The context switch would be taken by the Xen scheduler, not the Linux > scheduler. [...] The 'slim hypervisor' model i was suggesting was a slimmed down _Linux_ kernel. Ingo _______________________________________________ Xen-users mailing list Xen-users@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-users
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