On Tue, Dec 01, 2020 at 02:48:11PM +0100, Thomas Gleixner wrote: > On Mon, Nov 30 2020 at 16:16, Marcelo Tosatti wrote: > >> Besides, Linux guests don't sync the TSC via IA32_TSC write, > >> but rather use IA32_TSC_ADJUST which currently doesn't participate > >> in the tsc sync heruistics. > > > > Linux should not try to sync the TSC with IA32_TSC_ADJUST. It expects > > the BIOS to boot with synced TSCs. > > That's wishful thinking. > > Reality is that BIOS tinkerers fail to get it right. TSC_ADJUST allows > us to undo the wreckage they create. > > Thanks, > > tglx Have not seen any multicore Dell/HP systems require that. Anyway, for QEMU/KVM it should be synced (unless there is a bug in the sync logic in the first place).
