Re: [PATCH RFC] sched: deferred set priority (dprio)

[Andi Kleen]

> (One example might be virtual machine that runs guest operating system that is
> not paravirtualized or can be paravirtualized only to a limited extent. The VM
> might guess that preemption of VCPU thread that is processing events such as
> IPI interrupts, clock interrupts or certain device interrupts is likely to
> cause overall performance degradation due to other VCPUs spinning for an IPI
> response or spinning waiting for a spinlock, and thought the general kinds of
> these dependencies may be foreseen, but actual dependency chains between VCPUs
> cannot be established at run time.)

PAUSE loop exiting (PLE) can handle it in limited fashion on VMs
even without paravirtualization.

-Andi
-- 
ak@xxxxxxxxxxxxxxx -- Speaking for myself only.
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