Good day. I have come across the occasional issue of clock drift when running (earlier) kernels inside a virtual machine. The reason for drift is simple enough - host may be under heavy load, guest may not get enough resources to run all the ticks (HZ) it is supposed to. At least to put it simply.
Now, I have been wondering how the introduction of CFS and CONFIG_NOHZ (dynticks) change this, or if they do at all. If I have understood correctly, only the host's scheduler is really involved so it enters the picture when host is running a recent kernel. In a pure hypervisor-only virtualization, that point should be moot. And then we have dynticks. Try as I might, I haven't been able to wrap my head around the combination. What happens to the kernel and timekeeping when guest has NOHZ enabled? My google-fu is not good enough to find the relevant documentation if such even exists on this subject. To top it off, I'm not certain whether my question is trivial, non-issue or just plain weird. Any pointers on where I should look for more information will be appreciated. -- Mika Boström +358-40-525-7347 -=- The flogging will continue [EMAIL PROTECTED] www.iki.fi/bostik -=- until morale improves GPG: 0x039F188E; EC67 5B3A E6E3 6A84 9CB2 94D3 BFCD BD57 039F 188E -- 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/
