Il 17/03/2014 19:54, Peter Zijlstra ha scritto:
On Mon, Mar 17, 2014 at 01:44:34PM -0400, Waiman Long wrote:
The PV ticketlock code was designed to handle lock holder preemption by
redirecting CPU resources in a preempted guest to another guest that can
better use it and then return the preempted CPU back sooner.
But that's the PV code, not the unfair bit. And your fuller PV thing
doesn't need the unfair option.
I agree. You need three cases:
* non-virt, non-PV: regular qspinlock
* virt (X86_FEATURE_HYPERVISOR), non-PV: test-and-set
* virt, PV: disables test-and-set, adds PV waiting to qspinlock
Paolo
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