Hi, We (a cloud hosting provider) has recently observed a couple of strange lockups when physical node runs significant amount of Win2008R2 kvm appliances, one may see collection of those lockups at the link below. After checking a lot of ideas without any valuable result, I have suggested that nested per-thread cgroup placement created by libvirt may lead to this problem(libvirt puts emulator and each of vcpu threads into separate sub-cgroup). Disabling such behavior, e.g. having only one cgroup per kvm process per cgroup type solved this problem, at least it didn`t happen on most stressful tests we`re able to do. Since it is generally unusual for well-known kernel mechanism, such as cgroups, to broke way like this, I hope we`ve found a quite rare kind of bug. Just for the record, the bug also may happen using linux guest, but much rarely, one or two orders of magnitude. We have stayed on default scheduler granularity value at this tests, if it matters. For anyone who wants to see entire timeline of this bug, please see [1]. [1]. http://www.spinics.net/lists/kvm/msg85956.html -- 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
