On 07/18/2018 09:15 PM, Konrad Rzeszutek Wilk wrote: > On Tue, Jul 17, 2018 at 05:59:27PM -0400, Waiman Long wrote: >> On a VM with only 1 vCPU, the locking fast path will always be >> successful. In this case, there is no need to use the the PV qspinlock >> code which has higher overhead on the unlock side than the native >> qspinlock code. > Why not make this global? That is for both KVM and Xen and any > other virtualized guest that uses this? Right, I will send another patch for Xen. The pvqspinlock code has to be explicitly opted in. Right now, both Xen and KVM used it in the tree. I am not sure about other out-of-tree modules. There is nothing I can do for those. Cheers, Longman