Steal time accounts the time duration during which a guest vcpu was ready to run, but was not scheduled to run by the hypervisor. This is particularly relevant in cloud environment where customers would want to use this as an indicator that their guests are being throttled. However, as it stands today, guest steal time information is not visible from the hypervisor. For cloud service providers, this is problematic since they would want to overcommit cpu resources to achieve optimum resource utilization while at the same time ensuring guests are not throttled. It is useful for service providers to have access to the guest steal time data so that they can base their overcommit/guest packing decisions on this. Higher guest steal time can be used as a trigger to change how the guests are scheduled, or even migrate guests out of a system. This patchset attempts to make the guest steal times available in the host. This is achieved by introducing a new field in per-task statistics (/proc/<pid>/stat and /proc/<pid>/task/<pid>/stat) to accumulate per-vcpu steal time. Programs (such as pidstat) can then be enhanced to report this information on a per-thread basis. This should also work for nested virtualization: steal time information for the guest is readable via /proc/stat, while steal time information for guests hosted on this hypervisor is readable via /proc/<pid>/task/*/stat. Also, mpstat always shows steal time information for current (self) guest on a per-cpu basis. And pidstat can be enhanced to report the same for the hosted guests on a per-vcpu basis. As an example: Guest (self) steal time information using mpstat: ------------------------------------------------ mpstat is run from within the guest. [root@rhel7-img ~]# mpstat -P ALL 1 Linux 3.19.0nnr (rhel7-img) 04/15/2015 _ppc64_ (4 CPU) 03:13:23 PM CPU %usr %nice %sys %iowait %irq %soft %steal %guest %gnice %idle 03:13:24 PM all 12.25 0.00 1.25 0.00 1.00 2.25 13.75 0.00 0.00 69.50 03:13:24 PM 0 46.53 0.00 0.00 0.00 0.00 4.95 45.54 0.00 0.00 2.97 03:13:24 PM 1 0.00 0.00 0.00 0.00 0.00 4.04 3.03 0.00 0.00 92.93 03:13:24 PM 2 0.00 0.00 0.00 0.00 3.96 0.99 2.97 0.00 0.00 92.08 03:13:24 PM 3 3.00 0.00 4.00 0.00 0.00 0.00 4.00 0.00 0.00 89.00 03:13:24 PM CPU %usr %nice %sys %iowait %irq %soft %steal %guest %gnice %idle 03:13:25 PM all 12.59 0.00 0.00 0.00 0.00 0.25 12.35 0.00 0.00 74.81 03:13:25 PM 0 50.00 0.00 0.00 0.00 0.00 0.98 49.02 0.00 0.00 0.00 03:13:25 PM 1 0.98 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 99.02 03:13:25 PM 2 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100.00 03:13:25 PM 3 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100.00 03:13:25 PM CPU %usr %nice %sys %iowait %irq %soft %steal %guest %gnice %idle 03:13:26 PM all 12.99 0.00 0.00 0.00 0.25 0.00 12.75 0.00 0.00 74.02 03:13:26 PM 0 51.96 0.00 0.00 0.00 0.00 0.00 48.04 0.00 0.00 0.00 03:13:26 PM 1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100.00 03:13:26 PM 2 0.00 0.00 0.00 0.00 0.98 0.00 2.94 0.00 0.00 96.08 03:13:26 PM 3 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100.00 03:13:26 PM CPU %usr %nice %sys %iowait %irq %soft %steal %guest %gnice %idle 03:13:27 PM all 12.53 0.00 1.00 0.25 0.00 0.25 12.03 0.00 0.00 73.93 03:13:27 PM 0 51.02 0.00 0.00 0.00 0.00 0.00 48.98 0.00 0.00 0.00 03:13:27 PM 1 0.00 0.00 4.04 0.00 0.00 0.00 0.00 0.00 0.00 95.96 03:13:27 PM 2 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100.00 03:13:27 PM 3 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100.00 Average: CPU %usr %nice %sys %iowait %irq %soft %steal %guest %gnice %idle Average: all 12.91 0.00 0.54 0.01 0.04 0.12 12.39 0.00 0.00 74.00 Average: 0 51.36 0.00 0.03 0.00 0.03 0.26 48.27 0.00 0.00 0.05 Average: 1 0.02 0.00 1.54 0.02 0.02 0.15 0.36 0.00 0.00 97.89 Average: 2 0.00 0.00 0.52 0.00 0.09 0.02 0.36 0.00 0.00 99.02 Average: 3 0.05 0.00 0.07 0.00 0.02 0.09 0.34 0.00 0.00 99.43 Steal time information for hosted guests in host using (locally modified) pidstat: --------------------------------------------------------------------------------- pidstat is being run in the host. [naveen@xxxxxxxxxx sysstat]$ ./pidstat -C qemu -tIu 1 Linux 3.19.0nnr (xxxxxxxxxx.in.ibm.com) 04/15/2015 _ppc64_ (64 CPU) 04:43:20 AM UID TGID TID %usr %system %guest %CPU %steal CPU Command 04:43:22 AM 1008 3001 - 0.00 0.00 54.21 3.39 45.79 12 qemu-system-ppc 04:43:22 AM 1008 - 3005 0.00 0.00 54.21 3.39 0.00 12 |__qemu-system-ppc 04:43:22 AM UID TGID TID %usr %system %guest %CPU %steal CPU Command 04:43:23 AM 1008 3001 - 0.00 0.00 52.00 3.25 46.00 12 qemu-system-ppc 04:43:23 AM 1008 - 3003 0.00 0.00 2.00 0.12 46.00 12 |__qemu-system-ppc 04:43:23 AM 1008 - 3005 0.00 0.00 45.00 2.81 0.00 12 |__qemu-system-ppc 04:43:23 AM 1008 - 3006 0.00 0.00 6.00 0.38 0.00 12 |__qemu-system-ppc 04:43:23 AM UID TGID TID %usr %system %guest %CPU %steal CPU Command 04:43:24 AM 1008 3001 - 0.00 2.00 50.00 3.25 67.00 12 qemu-system-ppc 04:43:24 AM 1008 - 3001 0.00 1.00 0.00 0.06 0.00 12 |__qemu-system-ppc 04:43:24 AM 1008 - 3003 0.00 0.00 8.00 0.50 49.00 12 |__qemu-system-ppc 04:43:24 AM 1008 - 3004 0.00 0.00 2.00 0.12 5.00 12 |__qemu-system-ppc 04:43:24 AM 1008 - 3005 0.00 0.00 38.00 2.38 3.00 12 |__qemu-system-ppc 04:43:24 AM 1008 - 3006 0.00 1.00 0.00 0.06 8.00 12 |__qemu-system-ppc 04:43:24 AM UID TGID TID %usr %system %guest %CPU %steal CPU Command 04:43:25 AM 1008 3001 - 0.00 0.00 51.00 3.19 47.00 12 qemu-system-ppc 04:43:25 AM 1008 - 3003 0.00 0.00 27.00 1.69 47.00 12 |__qemu-system-ppc 04:43:25 AM 1008 - 3004 0.00 1.00 0.00 0.06 0.00 12 |__qemu-system-ppc 04:43:25 AM 1008 - 3005 0.00 1.00 23.00 1.50 0.00 12 |__qemu-system-ppc 04:43:25 AM 1008 - 3006 0.00 0.00 2.00 0.12 0.00 12 |__qemu-system-ppc 04:43:25 AM UID TGID TID %usr %system %guest %CPU %steal CPU Command 04:43:26 AM 1008 3001 - 0.00 0.00 51.00 3.18 53.00 12 qemu-system-ppc 04:43:26 AM 1008 - 3003 0.00 0.00 9.00 0.56 50.00 12 |__qemu-system-ppc 04:43:26 AM 1008 - 3005 0.00 0.00 16.00 1.00 3.00 12 |__qemu-system-ppc 04:43:26 AM 1008 - 3006 0.00 0.00 26.00 1.62 0.00 12 |__qemu-system-ppc Average: UID TGID TID %usr %system %guest %CPU %steal CPU Command Average: 1008 3001 - 0.00 0.18 51.54 3.23 50.12 - qemu-system-ppc Average: 1008 - 3001 0.02 0.02 0.00 0.00 0.00 - |__qemu-system-ppc Average: 1008 - 3003 0.00 0.03 15.89 0.99 48.24 - |__qemu-system-ppc Average: 1008 - 3004 0.00 0.05 11.70 0.73 0.56 - |__qemu-system-ppc Average: 1008 - 3005 0.00 0.06 20.03 1.26 0.58 - |__qemu-system-ppc Average: 1008 - 3006 0.00 0.03 3.93 0.25 0.72 - |__qemu-system-ppc - Naveen ------ Changes since RFC: Updated description to clarify few aspects that I got questions about. No code changes. Naveen N. Rao (3): procfs: add guest steal time in /proc/<pid>/stat kvm/x86: report guest steal time in host kvm/powerpc: report guest steal time in host arch/powerpc/include/asm/kvm_host.h | 1 + arch/powerpc/kernel/asm-offsets.c | 1 + arch/powerpc/kvm/book3s_hv.c | 2 ++ arch/powerpc/kvm/book3s_hv_rmhandlers.S | 3 +++ arch/x86/kvm/x86.c | 1 + fs/proc/array.c | 6 ++++++ include/linux/sched.h | 7 +++++++ kernel/fork.c | 2 +- 8 files changed, 22 insertions(+), 1 deletion(-) -- 2.3.7 -- 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
