Am 22.04.2015 um 12:24 schrieb Naveen N. Rao: > 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 [If there is a better place/way to expose > this, please let me know]. As an example, with pidstat on ppc64: > > Guest steal time information using mpstat: > ----------------------------------------- > > [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 in host using (locally modified) pidstat: > --------------------------------------------------------------- > > [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 > > > On x86, we can obtain accurate steal time information since it is just the > scheduler run_delay. However, on powerpc, obtaining accurate steal time > information is challenging. This patchset proposes a technique that allows us > to obtain a reasonable (+/- 5%) approximation. Please suggest if there are > better ways to achieve more accurate steal time accounting in the hypervisor. I > am also interested in general feedback on the overall patchset and my approach > for the same. > > > Thanks! > - Naveen When adding new interfaces regarding steal time etc, can you add the s390 list CC? s390 is doing steal time calculation also with hardware support: we have two type of timers, one compares agains the TOD clock, which steps with the wall clock, the other timer steps only if the guest CPU is backed by a real CPU. So, _IF_ this interface is introduced it would be good to have some s390 point of view included in that discussion. Christian -- To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
