Linux HZ checker

22 01 2008

HZ defined how many ticks the internal timer interrupt in 1sec, which means the number of jiffies count in 1 sec.

Different architecture/machine may have different HZ value, you can check using this script from the timer interrupt:

#!/bin/sh
while [ 1 ]; do
A=`cat /proc/interrupts | grep timer | cut -d ‘:’ -f 2 |sed -e ‘s/[^0-9]//g’`
sleep 1
B=`cat /proc/interrupts | grep timer | cut -d ‘:’ -f 2 |sed -e ‘s/[^0-9]//g’`
C=$(($B-$A));
echo “HZ:$C”
done

it is around 250 in my desktop running 2.6, but 100 in my mips 2.4 embedded board.

Sometimes we may need to know the time in seconds from jiffies in kernel.

time(sec) = jiffies/HZ;

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