On Sun, Dec 11, 2011 at 02:40:58PM +0200, Dor Laor wrote: > >>When a guest kernel is stopped by the host hypervisor it can look like a soft > >>lockup to the guest kernel. This false warning can mask later soft lockup > >>warnings which may be real. This patch series adds a method for a host > >>hypervisor to communicate to a guest kernel that it is being stopped. The > >>final patch in the series has the watchdog check this flag when it goes to > >>issue a soft lockup warning and skip the warning if the guest knows it was > >>stopped. > >> > >>It was attempted to solve this in Qemu, but the side effects of saving and > >>restoring the clock and tsc for each vcpu put the wall clock of the guest behind > >>by the amount of time of the pause. This forces a guest to have ntp running > >>in order to keep the wall clock accurate. > > Guests need to run NTP regardless, not only the virtualization layer > add some skew, the physical world is not that perfect. > btw: traditional NTP client won't sync the time automatically if the > diff is > 0.5%. > > > > >Having this controlled from userspace means it doesn't work for SIGSTOP > >or for long scheduling delays. What about doing this automatically > >based on preempt notifiers? > > > > > > Isn't it solved by steal time? No. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
