C-State

C-State residencies are collected from hardware and/or the operating system (OS).

For systems that collect OS C-State residencies, CPU C-states are core power states requested by the Operating System Directed Power Management (OSPM) infrastructure that define the degree to which the processor is "idle".

For systems that collect hardware C-State residencies, CPU C-States are obtained by reading the processor’s MSRs which count the actual time spent in each C-State.

C-States range from C0 to Cn. C0 indicates an active state. All other C-states (C1-Cn) represent idle sleep states where the processor clock is inactive (cannot execute instructions) and different parts of the processor are powered down. As the C-States get deeper, the exit latency duration becomes longer (the time to transition to C0) and the power savings becomes greater.

Note

This metric is collected as part of energy analysis. Collecting energy analysis data with Intel® SoC Watch is available for target Android*, Windows*, or Linux* devices and provided only with the Intel System Studio. Import and viewing of the Intel SoC Watch results is supported with any version of the VTune Amplifier.

For more complete information about compiler optimizations, see our Optimization Notice.
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