> not guaranteed to be precise. For example a SMI (System Management > Interrupt) could interrupt the software flow that is attempting to write > the time-stamp counter immediately prior to the WRMSR. This could mean > the value written to the TSC could vary by thousands to millions of > clocks.
Yes SMI is a disaster area for any real time activity (and many other things ;) ), but many systems actually make little use of it, especially once the USB is owned by the OS. For synchronization you can retry the sync if it isn't within an acceptable range. The odds of getting an SMI mid sync setup should be very very low, so the odds of repeating the failure several times should be negligible and after a few tries you could give up and assume the hardware is buggered then fall back to HPET. Alan -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
