On 19/04/21 18:32, Sean Christopherson wrote:
If false positives are a big concern, what about adding another pass to the loop and only yielding to usermode vCPUs with interrupts in the second full pass? I.e. give vCPUs that are already in kernel mode priority, and only yield to handle an interrupt if there are no vCPUs in kernel mode. kvm_arch_dy_runnable() pulls in pv_unhalted, which seems like a good thing.
pv_unhalted won't help if you're waiting for a kernel spinlock though, would it? Doing two passes (or looking for a "best" candidate that prefers kernel mode vCPUs to user mode vCPUs waiting for an interrupt) seems like the best choice overall.
Paolo
