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Display CPU usage in percentage

Terminal - Display CPU usage in percentage
NUMCPUS=`grep ^proc /proc/cpuinfo | wc -l`; FIRST=`cat /proc/stat | awk '/^cpu / {print $5}'`; sleep 1; SECOND=`cat /proc/stat | awk '/^cpu / {print $5}'`; USED=`echo 2 k 100 $SECOND $FIRST - $NUMCPUS / - p | dc`; echo ${USED}% CPU Usage
2012-10-02 03:57:51
User: toxick
Functions: awk echo sleep wc
Display CPU usage in percentage

Using the output of 'ps' to determine CPU usage is misleading, as the CPU column in 'ps' shows CPU usage per process over the entire lifetime of the process. In order to get *current* CPU usage (without scraping a top screen) you need to pull some numbers from /proc/stat. Here, we take two readings, once second apart, determine how much IDLE time was spent across all CPUs, divide by the number of CPUs, and then subtract from 100 to get non-idle time.


There is 1 alternative - vote for the best!

Terminal - Alternatives
ps aux | awk {'sum+=$3;print sum'} | tail -n 1

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What others think

Granted this only works on devices where HZ=100. Alternatively, this may work for other systems:

HZ=`awk '/\#define HZ/ {print $3}' /usr/include/asm-generic/param.h`; NUMCPUS=`grep ^proc /proc/cpuinfo | wc -l`; FIRST=`cat /proc/stat | awk '/^cpu / {print $5}'`; sleep 1; SECOND=`cat /proc/stat | awk '/^cpu / {print $5}'`; USED=`echo 4 k 100 $SECOND $FIRST - $NUMCPUS $HZ \* / 100 \* - p | dc`; echo ${USED}% CPU Usage

Deriving HZ from the include files.

Comment by toxick 164 weeks and 2 days ago

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