On Mon, Jan 29, 2018 at 1:50 PM, Eduardo Habkost <ehabkost@xxxxxxxxxx> wrote: > On Mon, Jan 29, 2018 at 01:37:05PM -0800, Jim Mattson wrote: >> For GCE, "you might be migrated to Skylake" is pretty much a >> certainty. Even if you're in a zone that doesn't currently have >> Skylake machines, chances are pretty good that it will have Skylake >> machines some day in the not-too-distant future. > > This kind of scenario is why I suggest a "we promise you're not > going to be migrated to Skylake" bit instead a "you may be > migrated to Skylake" bit. The hypervisor could prevent migration > to Skylake hosts if management software chose to enable this bit, > and guests would choose the safest option (i.e. assume the worst) > if running on older hypervisors that don't set the bit. Giving customers this option promises the logistical nightmare of provisioning sufficient pre-Skylake-era machines in all pools until sufficient post-Skylake-era machines can be deployed to replace them. >> In general, making these kinds of decisions based on F/M/S is probably >> unwise when running in a VM. > > Certainly. That's why I suggest not trusting f/m/s unless the > hypervisor is explicitly saying it's accurate. > > -- > Eduardo
