On 18/05/2018 18:04, Eduardo Habkost wrote: >> Without mlock you should always use pv spinlocks. >> >> Otherwise you risk blocking on a lock taken by >> a VCPU that is in turn blocked on IO, where the IO >> is not completing because CPU is being used up >> spinning. > > So the stronger guarantee seems necessary. > > Now what should host userspace do if the user is trying to run an > existing configuration where the CPUID hint was set but memory is > not pinned? As mentioned elsewhere in the thread, there are many ways to pin memory, and mlock is not always necessary. However, I agree with Michael in making the hint provide a stronger guarantee. Paolo
