On 14.09.2019 10:52, Juergen Gross wrote: > This is achieved by switching the scheduler to no longer see vcpus as > the primary object to schedule, but "schedule units". Each schedule > unit consists of as many vcpus as each core has threads on the current > system. The vcpu->unit relation is fixed.
There's another aspect here that, while perhaps obvious, I didn't realize so far: Iirc right now schedulers try to place vCPU-s on different cores, as long as there aren't more runnable vCPU-s than there are cores. This is to improve overall throughput, since vCPU-s on sibling hyperthreads would compete for execution resources. With a fixed relation this is going to be impossible. Otoh I can of course see how, once we have proper virtual topology, this allows better scheduling decisions inside the guest, in particular if - under the right circumstances - it is actually wanted to run two entities on sibling threads. Jan _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
