Description of problem: Intel Core i7 system with 6 VMs has high system utilization in intel_idle driver. Version-Release number of selected component (if applicable): Fedora 20 Linux kernel 3.14.7-200.fc20.x86_64 Intel Core i7 920 Motherboard Supermicro - Chipset Intel X58 How reproducible: persistent Steps to Reproduce: 1. start system 2. start VMs 3. watch system utilization (vmstat) Actual results: system consumes 10% of CPU in sytem tasks Expected results: system should use less resources Additional info: A vmstat: procs -----------memory---------- ---swap-- -----io---- -system-- ----cpu---- r b swpd free buff cache si so bi bo in cs us sy id wa 0 0 0 14361496 171508 664704 0 0 0 68 7107 17688 6 10 84 0 0 0 0 14364152 171508 664704 0 0 0 0 6488 14111 5 11 84 0 1 0 0 14366256 171508 664708 0 0 0 0 6791 14200 6 12 82 0 1 0 0 14367736 171508 664708 0 0 0 32 6624 15677 6 10 84 0 0 0 0 14366164 171508 664708 0 0 0 0 6258 14805 6 9 85 0 0 0 0 14367912 171508 664708 0 0 0 0 6330 14187 6 12 82 0 1 0 0 14370316 171508 664732 0 0 0 0 6793 15457 6 10 84 0 The system has ksm/qemu running so we divide the system calls further into those additional processes. For the math we use: System time of ksm: take system times from /proc/ksm-pid/stat System time of qemu: sum system times from /proc/qemu-pids/stat System time rest: System time /proc/stat - qemu/system - ksm/system The collected data is attached in an rrd graph. As you can see half of the 11% system times go to ksm/qemu. The rest cannot be identified. A perf record -a -g gives as top "consumer" very high utilization in intel_idle driver - 9,16% swapper [kernel.kallsyms] [k] intel_idle - intel_idle - 99,89% cpuidle_enter_state cpuidle_idle_call arch_cpu_idle - cpu_startup_entry 68,72% start_secondary - 31,28% rest_init start_kernel x86_64_start_reservations x86_64_start_kernel - 5,82% ksmd [kernel.kallsyms] [k] memcmp - memcmp - 98,94% memcmp_pages - 96,81% ksm_scan_thread kthread ret_from_fork + 3,19% try_to_merge_with_ksm_page + 1,06% ksm_scan_thread A second server with a similar load does not expose that behaviour. Is that desired? Where should I start to look?
Created attachment 910305 [details] utilization graph
*********** MASS BUG UPDATE ************** We apologize for the inconvenience. There is a large number of bugs to go through and several of them have gone stale. Due to this, we are doing a mass bug update across all of the Fedora 20 kernel bugs. Fedora 20 has now been rebased to 3.17.2-200.fc20. Please test this kernel update (or newer) and let us know if you issue has been resolved or if it is still present with the newer kernel. If you have moved on to Fedora 21, and are still experiencing this issue, please change the version to Fedora 21. If you experience different issues, please open a new bug report for those.
This bug is being closed with INSUFFICIENT_DATA as there has not been a response in over 3 weeks. If you are still experiencing this issue, please reopen and attach the relevant data from the latest kernel you are running and any data that might have been requested previously.