On Tue, Oct 14, 2014 at 04:11:18AM -0700, Thomas Shao wrote: > In current hyper-v time sync service,it only gets the initial clock time > from the host. It didn't process the following time samples. This change > introduced a module parameter called host_time_sync. If it is set to true, > the guest will periodically sychronize it's time with the host clock using > host time sample. By default it is disabled, because we still recommend > user to configure NTP for time synchronization.
I really don't see the need for this. We have NTP. If the guests want to, they may use it. Otherwise, they have a free running clock, just like real machines. > + /* > + * Use the Hyper-V time sample to adjust the guest time. The > + * algorithm is: If the sample offsets exceeds 1 second, we > + * directly set the clock to the server time. If the offset is So the guests will experience random time jumps in the kernel, without any rhyme or reason? > + * less than 1ms, we ignore the time sample. Otherwise we adjust > + * the clock. > + */ So when using this kernel module, the sychronization is never expected to be better than one millisecond. That is not too good. I expect NTP can do better. So what was the point of this change again? Thanks, Richard -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
