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I ran a process which uses 100% CPU: stress -c 1.

In powertop, the "Idle stats" tab shows about 120% "C0 active" for the busy logical CPU.

By contrast when turbostat is used, turbostat --show Busy% shows about 100% for this logical CPU, as expected.

What does it mean to have more than 100% "C0 active" in powertop? Is it a bug?


  • My current kernel is a vanilla 5.1 build. The kernel config is mostly derived from Fedora Linux kernel config (but built with localmodconfig).
  • powertop-2.10-2.fc29.x86_64
  • kernel-tools-5.0.9-200.fc29.x86_64 - package containing the turbostat command
# lscpu
Architecture:        x86_64
CPU op-mode(s):      32-bit, 64-bit
Byte Order:          Little Endian
CPU(s):              4
On-line CPU(s) list: 0-3
Thread(s) per core:  2
Core(s) per socket:  2
Socket(s):           1
NUMA node(s):        1
Vendor ID:           GenuineIntel
CPU family:          6
Model:               61
Model name:          Intel(R) Core(TM) i5-5300U CPU @ 2.30GHz
Stepping:            4
CPU MHz:             973.550
CPU max MHz:         2900.0000
CPU min MHz:         500.0000
BogoMIPS:            4589.08
Virtualization:      VT-x
L1d cache:           32K
L1i cache:           32K
L2 cache:            256K
L3 cache:            3072K
NUMA node0 CPU(s):   0-3
Flags:               fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc cpuid aperfmperf pni pclmulqdq dtes64 monitor ds_cpl vmx smx est tm2 ssse3 sdbg fma cx16 xtpr pdcm pcid sse4_1 sse4_2 x2apic movbe popcnt tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm abm 3dnowprefetch cpuid_fault epb invpcid_single pti ssbd ibrs ibpb stibp tpr_shadow vnmi flexpriority ept vpid ept_ad fsgsbase tsc_adjust bmi1 hle avx2 smep bmi2 erms invpcid rtm rdseed adx smap intel_pt xsaveopt dtherm ida arat pln pts flush_l1d
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powertop needs to be calibrated on mobile devices, specifically including your Intel i5-5300U CPU.

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  • When running on battery, powertop can track power consumption as well as system activity. When there are enough measurements, powertop can start to report power estimates. One can get more accurate estimates by using this option to enable a calibration cycle. But the % time in "C0 active" is not a "power estimate", right? – sourcejedi May 7 '19 at 18:58
  • Please try it and report. – K7AAY May 7 '19 at 19:01
  • Thanks for the great question edit! On this basis so far, I do not plan to perform the test which requires leaving the system alone for one hour. – sourcejedi May 7 '19 at 19:13

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