2016-07-06 15:58 GMT+08:00 Peter Zijlstra [off-list ref]:

On Wed, Jul 06, 2016 at 02:46:34PM +0800, Wanpeng Li wrote:

quoted

quoted

SO it's easy for ppc to implement such interface. Note that yield_count is
set by powerVM/KVM.
and only pSeries can run a guest for now. :)

I also review x86 related code, looks like we need add one hyer-call to get
such vcpu preemption info?

There is no such stuff to record lock holder in x86 kvm, maybe we
don't need to depend on PLE handler algorithm to guess it if we can
know lock holder vCPU directly.

x86/kvm has vcpu->preempted to indicate if a vcpu is currently preempted
or not. I'm just not sure if that is visible to the guest or how to make
it so.

Yeah, I miss it. I can be the volunteer to do it if there is any idea,
ping Paolo. :)

Regards,
Wanpeng Li