Re: [kvm-devel] [PATCH 2/2] KVM: Use the scheduler preemption hooks to make kvm preemptible

[Luca <kronos.it@gmail.com>]

On 7/11/07, Avi Kivity <avi@qumranet.com> wrote:
> Current kvm disables preemption while the new virtualization registers are
> in use.  This of course is not very good for latency sensitive workloads (one
> use of virtualization is to offload user interface and other latency
> insensitive stuff to a container, so that it is easier to analyze the
> remaining workload).  This patch re-enables preemption for kvm; preemption
> is now only disabled when switching the registers in and out, and during
> the switch to guest mode and back.
[...]
> diff --git a/drivers/kvm/Kconfig b/drivers/kvm/Kconfig
> index 33fa28a..92644b5 100644
> --- a/drivers/kvm/Kconfig
> +++ b/drivers/kvm/Kconfig
> @@ -10,7 +10,7 @@ if VIRTUALIZATION
>
>  config KVM
>         tristate "Kernel-based Virtual Machine (KVM) support"
> -       depends on X86 && EXPERIMENTAL
> +       depends on X86 && EXPERIMENTAL && PREEMPT_HOOKS
>         depends on X86_CMPXCHG64 || 64BIT

select PREEMPT_HOOKS maybe?

Luca