Re: [PATCH RFC 0/2] kvm: Improving directed yield in PLE handler

[Avi Kivity]

On 07/12/2012 05:17 AM, Benjamin Herrenschmidt wrote:
>> ARM doesn't have an instruction for cpu_relax(), so it can't intercept
>> it.  Given ppc's dislike of overcommit, and the way it implements
>> cpu_relax() by adjusting hw thread priority, I'm guessing it doesn't
>> intercept those either, but I'm copying the ppc people in case I'm
>> wrong.  So it's s390 and x86.
> 
> No but our spinlocks call __spin_yield()  (or __rw_yield) which does
> some paravirt tricks already.
> 
> We check if the holder is currently running, and if not, we call the
> H_CONFER hypercall which can be used to "give" our time slice to the
> holder.
> 
> Our implementation of H_CONFER in KVM is currently a nop though.

Okay, so you can join the party.  See yield_to() and kvm_vcpu_on_spin().

-- 
error compiling committee.c: too many arguments to function


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