Re: [Qemu-devel] kvmclock, Migration, and NTP clock jitter

2015-01-21 Thread Mohammed Gamal
On Fri, Jan 16, 2015 at 11:21 AM, Mohammed Gamal < mohammed.ga...@profitbricks.com> wrote: > On Thu, Jan 15, 2015 at 06:27:54PM +0100, Paolo Bonzini wrote: > > > > > > On 15/01/2015 17:39, Mohammed Gamal wrote: > > > The increase in the jitter and offset values is well within the 500 ppm > > > fre

Re: [Qemu-devel] kvmclock, Migration, and NTP clock jitter

2015-01-16 Thread Mohammed Gamal
On Thu, Jan 15, 2015 at 06:27:54PM +0100, Paolo Bonzini wrote: > > > On 15/01/2015 17:39, Mohammed Gamal wrote: > > The increase in the jitter and offset values is well within the 500 ppm > > frequency tolerance limit, and therefore are easily corrected by > > subsequent NTP clock sync events, bu

Re: [Qemu-devel] kvmclock, Migration, and NTP clock jitter

2015-01-15 Thread Paolo Bonzini
On 15/01/2015 17:39, Mohammed Gamal wrote: > The increase in the jitter and offset values is well within the 500 ppm > frequency tolerance limit, and therefore are easily corrected by > subsequent NTP clock sync events, but some live migrations do cause much > higher jitter and offset jumps, whic

[Qemu-devel] kvmclock, Migration, and NTP clock jitter

2015-01-15 Thread Mohammed Gamal
Hi, I've seen some strange time behavior in some of our VMs usually triggered by live migration. In some VMs we have seen some significant time drift which NTP was not able to correct after doing a live migration. I've not been able so far to reproduce the same case, however, I did notice that li