[libvirt] time: event poll may become un-triggerable after changing system clock.

zhang bo oscar.zhangbo at huawei.com
Wed May 13 00:54:49 UTC 2015

On 2015/5/12 16:56, Daniel P. Berrange wrote:

> On Tue, May 12, 2015 at 04:14:37PM +0800, zhang bo wrote:

>> So, Is there any other better solution? thanks in advance.
> Simply don't change the system time by massive deltas. Libvirt is not going
> to be the only app to be affected. As you mention it is going to hit the
> pthread_cond_wait() call which will likely affect pretty much every single
> non-trivial process running on the system. I'd expect other apps have much
> the same problem with calculating poll sleeps too.
> If you need to massively change the system time this should be done at
> single user mode, or do a reboot. Once a system is running it should be
> kept synced with NTPD which will only ever change system time in very
> small increments and so once cause thsi problem.
> Regards,
> Daniel

Thank you Daniel. 
Would you please explain more about what "single user mode" mean here? and does "reboot" refers to
"rebooting the os" or "rebooting the process libvirtd"?  I think it's "the process", right?

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