KernelTrap: Improving KVM Performance With A Tickless Kernel

“Avi Kivity suggested that combining KVM, the Kernel-based
Virtual Machine, with the dyntick patch could improve overall KVM
performance. He noted that it would likely improve performance of
both the host by ‘avoiding expensive vmexits due to useless timer
interrupts,’ as well as on the guest by “reducing the load on the
host when the guest is idling (currently an idle guest consumes a
few percent cpu)”. Ingo Molnar pointed out that KVM with his -rt
kernel already works with dynticks enabled on both the host and the
guest, ‘using the dynticks code from the -rt kernel makes the
overhead of an idle guest go down by a factor of 10-15.’ Ingo added
that he hopes the dyntick patch will be ready to be merged into the
upcoming mainline 2.6.21 kernel…”

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