Hi, Weeks ago, I developed my app under ubuntu-11.10 (kernel 3.0) with lilbvirt-0.9.10. In my code , I used virDomainGetCPUStats to query cpu usage info of domains, and it worked well. However, today, I port my code to ubuntu-10.04.4 (kernel 2.6.32) with libvirt-0.9.10, I find the function virDomainGetCPUStats can't work and complains "this function is not supported by the connection driver: virDomainGetCPUStats". I guess the kernel difference cause this problem because the libvirt is the same on two operating systems. I wonder what features of kernel are required to support virDomainGetCPUStats? I thought cgroup is a prerequisite. The following are .config files of two kernels. ubuntu-11.10 CONFIG_CGROUP_FREEZER=y CONFIG_CGROUP_DEVICE=y CONFIG_CPUSETS=y CONFIG_PROC_PID_CPUSET=y CONFIG_CGROUP_CPUACCT=y CONFIG_RESOURCE_COUNTERS=y CONFIG_CGROUP_MEM_RES_CTLR=y CONFIG_CGROUP_MEM_RES_CTLR_SWAP=y CONFIG_CGROUP_MEM_RES_CTLR_SWAP_ENABLED=y CONFIG_CGROUP_PERF=y CONFIG_CGROUP_SCHED=y CONFIG_FAIR_GROUP_SCHED=y CONFIG_RT_GROUP_SCHED=y CONFIG_BLK_CGROUP=y ubuntu-10.04.4 CONFIG_CGROUP_NS=y CONFIG_CGROUP_FREEZER=y CONFIG_CGROUP_DEVICE=y CONFIG_CPUSETS=y CONFIG_PROC_PID_CPUSET=y CONFIG_CGROUP_CPUACCT=y CONFIG_RESOURCE_COUNTERS=y CONFIG_CGROUP_MEM_RES_CTLR=y CONFIG_CGROUP_MEM_RES_CTLR_SWAP=y CONFIG_CGROUP_SCHED=y CONFIG_FAIR_GROUP_SCHED=y CONFIG_RT_GROUP_SCHED=y CONFIG_MM_OWNER=y As you can see, CPUSET and CPUACCT are enabled in both kernels. So what else features of kernel are required to support virDomainGetCPUStats? harvey