[PATCH] powerpc/pseries/cpuidle: add polling idle for shared processor guests

[Nicholas Piggin]

On Tue, 10 Oct 2017 17:11:09 +1000
Nicholas Piggin <npiggin at gmail.com> wrote:

> For shared processor guests (e.g., KVM), add an idle polling mode rather
> than immediately returning to the hypervisor when the guest CPU goes
> idle.
> 
> Test setup is a 2 socket POWER9 with 4 guests running, each with vCPUs
> equal to 1/2 of real of CPUs. Saturated each guest with tbench. Using
> polling idle gives about 1.4x throughput.

Actually it's even more noticeable when the host is not over subscribed
by the looks. 2.5x-3x increase in throughput for just a single guest.

Thanks,
Nick