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KVM Protecting host

Posted: 2011/08/28 11:39:50
by swallowtail
Being a fairly long term Xen user, I am trying to now learn KVM.

On my old CentOS 5.6 server, after having been stung in the past by a runaway guest consuming host CPU time to the point of making the entire group unresponsive, I made some changes as advised at - namely the following:

(dom0-min-mem 512)
(auto-balloon-dom0 no)

Grub menu.lst:
kernel /xen.gz-2.6.18-238.19.1.el5 dom0_mem=512M loglvl=all guest_loglvl=all

And finally edit /etc/rc.local:
xm sched-credit -d Domain-0 -w 512

Those settings have on a couple of occasions now saved my host's CPU time, allowing me to kill a badly behaving guest.

So - my question is, are similar techniques required under KVM to protect the host's CPU time? My new server will not be oversubscribed for guest RAM, so I am planning on disabling swap as per comments here That will prevent the host from swapping guest processes to disk, thus helping maintain responsiveness, but the interwebs seems pretty thin on detail about CPU scheduling for a KVM host... anyone shed any light / recommendations?