I've got a piece of userspace code which is parsing /proc/PID/task/TID/stat to get the cpu usage. I can use HZ to get the jiffies per second but this code could move to another machine which has a different configured value. Is there any way to get the value of HZ from userspace at runtime?
+1
A:
You divide it by the number you get from sysconf(_SC_CLK_TCK).
However, I think this is probably always 100 under Linux regardless of the actual clock tick, it's always presented to userspace as 100.
See man proc(5).
MarkR
2010-10-06 22:09:39
I did read that 100 is always presented to userspace... but wasn't sure /proc counted as userspace :)
Brian Makin
2010-10-06 22:43:14
I'm not certain I understand: does this mean that HZ is not actually the number that the questioner wanted?
Eric Seppanen
2010-10-07 15:40:26
HZ is the number I wanted... but it is a compiled in constant. As long as I'm running on the same machine I compiled for... all is good. But if I move to another machine without recompiling then it might have the wrong value.
Brian Makin
2010-10-08 13:55:49