[PATCH 0/2] KVM: add support for Pause-Loop exit

[Tim Gardner]

On 03/05/2010 07:42 AM, Andy Whitcroft wrote:
> Add kernel side support for KVM Pause-Loop exit.  This allows long lock
> spins in virtual machines to relinquish CPUs to other VMs.
>
> -apw
>
> Zhai, Edwin (2):
>    KVM: introduce kvm_vcpu_on_spin
>    KVM: VMX: Add support for Pause-Loop Exiting
>
>   arch/x86/include/asm/vmx.h |    4 +++
>   arch/x86/kvm/vmx.c         |   51 +++++++++++++++++++++++++++++++++++++++++++-
>   include/linux/kvm_host.h   |    1 +
>   virt/kvm/kvm_main.c        |   15 +++++++++++++
>   4 files changed, 70 insertions(+), 1 deletions(-)
>
>

These 2 clean upstream cherry-picks appear to preserve existing behavior 
if the module parameters ple_gap and ple_window are _not_ set.

In general I'm not in favor of adding features at this late stage, 
especially since there will be a backported kernel with this feature 
with the L+1 release.

These however appear benign while providing some performance benefit, so 
ACK from me. Please remember to add the upstream commit IDs.

rtg
-- 
Tim Gardner tim.gardner at canonical.com