> On Oct 4, 2018, at 5:00 AM, Paolo Bonzini <pbonzini@xxxxxxxxxx> wrote: > >> On 04/10/2018 09:54, Vitaly Kuznetsov wrote: >> - Check if pure TSC can be used on SkyLake+ systems (where TSC scaling >> is supported). > > Not if you want to migrate to pre-Skylake systems. > >> - Check if non-masterclock mode is still needed. E.g. HyperV's TSC page >> clocksource is a single page for the whole VM, not a per-cpu thing. Can >> we think that all the buggy hardware is already gone? > > No. :( We still get reports whenever we break 2007-2008 hardware. > > Does the KVM non-masterclock mode actually help? It’s not clear to me exactly how it’s supposed to work, but it seems like it’s trying to expose per-vCPU adjustments to the guest. Which is dubious at best, since the guest can’t validly use them for anything other than sched_clock, since they aren’t fully corrected by anything KVM can do. _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
