On 6/27/18 12:14 AM, Andriy Gapon wrote: > > It seems that TSC calibration in virtual machines sometimes can do more harm > than good. Should we default to trusting the information provided by a > hypervisor? > > Specifically, I am observing a problem on GCE instances where calibrated TSC > frequency is about 10% lower than advertised frequency. And apparently the > advertised frequency is the right one. > > I found this thread with similar reports and a variety of workarounds from > administratively disabling the calibration to switching to a different > timecounter: > https://lists.freebsd.org/pipermail/freebsd-cloud/2017-January/000080.html
I suspect you are probably right that we should just "trust" TSC frequencies provided by a hypervisor. We could perhaps choose to whitelist hypervisors known to provide accurate values if we wanted to be cautious. -- John Baldwin _______________________________________________ [email protected] mailing list https://lists.freebsd.org/mailman/listinfo/freebsd-current To unsubscribe, send any mail to "[email protected]"
