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Introduction
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The purpose of idlestat is to measure how long we have been in the different
idle and operating states.
Idlestat uses kernel's FTRACE function to monitor and capture C-state and
P-state transitions of CPUs over a time interval. It extracts the following
information from trace file:
- Times when CPUs entered and exited a certain C-state
- Times when CPUs entered and exited a certain P-state
- Raised IRQs
Following a successful run, idlestat calculates and reports the following
information:
- Total, average, minimum and maximum time spent in each C-state,
per-CPU.
- Total, average, minimum and maximum time spent in each P-state,
per-CPU.
- Total, average, minimum and maximum time during which all CPUs in
a cluster were in the same C-state, per-cluster.
- Number of times a certain IRQ caused a CPU to exit idle state,
per-CPU and per-IRQ
Requirements
------------
1. It must be run as root in order to access /sys/kernel/debug.
2. It requires tracing to be enabled in the kernel
Example Usage
-------------
./idlestat -d -o myoutput -t 10
where,
-d : dump the states at the end
-o : output file to store the traces
-t : the duration in seconds
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