Note
This analysis type is available as part of energy analysis. Energy analysis is provided by the Intel® VTune™ Amplifier for Systems only. Energy analysis collection is supported for target Android*, Windows* or Linux* devices.
The CPU Sleep States analysis monitors system hardware sleep states and explores how software behaviors are affecting those sleep states. To consume less power, different hardware components enter sleep states when they are idle. Ideally, hardware would enter a deep sleep state and stay there for a relatively long time before actively executing a workload again.
Use CPU Sleep States analysis data to analyze processor wake-up causes (for example, when the processor transitions from a sleep state to an active state). You can also determine if your application is causing wake-ups via timers. CPU Sleep States analysis can provide the call stack of the source code that scheduled a timer that later caused a wake-up.
To reduce energy consumption, you can eliminate unnecessary processor wake-ups either by eliminating or by coalescing timers wherever possible. CPU Sleep State analysis provides a timeline of wake-up activity, the causes of the wake-ups, and filters that can be used to isolate different behaviors and root causes of the wake-ups. VTune Amplifier detects the following causes of the processor wake-ups:
Kernel Timer
User Timer
IPI : Inter Processor Interrupt
IRQ : Interrupt Request
During the sleep state analysis collection, Intel® VTune™ Amplifier traces processor sleep state transitions and tries to identify the cause of each wake-up. The results show a timeline of the processor sleep states - C-states (the larger the C-state, the deeper the sleep and the greater the power saving) and wake-up activity per physical core. You can use filters to show the relevant data or zoom into periods of frequent wake-up activity to determine what might be causing the hardware to consume more power than necessary.
CPU Sleep State Analysis Results
VTune Amplifier displays the results of the CPU Sleep State analysis in the Platform Power Analysis viewpoint with the following windows. Some windows may or may not appear, depending on the data collected:
Summary window displays a summary of the data collected.
Core Wake-ups window displays wake-up objects which caused the core to switch from a sleep state to an active state.
Correlate Metrics window displays timelines for C-States per package and core, core frequencies, and kernel and user wakelocks, aligned on the same time scale.
CPU C/P States window displays sleep state data collected. The data is displayed according to the hierarchy for the platform on which the data was collected.