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SMP alternativesSMP alternativesPosted Dec 15, 2005 12:35 UTC (Thu) by NAR (subscriber, #1313)Parent article: SMP alternatives Virtualization systems (and Xen in particular) are implementing the ability to configure the number of (virtual) CPUs in each running instance on the fly, in response to the load on each. So it may really be that a busy, virtualized server will have CPUs hot-plugged into it, and that those processors will go away when the load drops. Why bother with hotplugging virtual processors? Isn't it simpler to add more resources (e.g. more CPU splices per second) on the host to the particular virtualized server?
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SMP alternatives Posted Dec 15, 2005 15:26 UTC (Thu) by bronson (subscriber, #4806) [Link] Yes, as long as you have more slices per second to give.
Once you've maxed out a single processor, your only recourse is to run the VM on more processors. AFAIK there's no good way of doing this unless the VM is partitioned (parallelized?) as well. Multiple virtual CPUs is the best way of doing this.
But the VM doesn't care! why not always run it in a quad-cpu configuration? Because that wastes cycles if it's just being run on a single CPU.
That's just a guess. It seems an overcomplex solution to me but I haven't looked at the code yet.
SMP alternatives Posted Dec 18, 2005 19:26 UTC (Sun) by bk (guest, #25617) [Link] Can these processors be on different physical machines? This sounds like an implementation of SSI clustering, which is pretty cool.
SMP alternatives Posted Dec 21, 2005 7:08 UTC (Wed) by csamuel (✭ supporter ✭, #2624) [Link] No.Xen is still running on a single system and whilst you can migrate a system between Xen servers (if you've got a shared filesystem that can cope) it only runs on one or the other with a tiny pause for the actual transition.
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