On oraclelinux with kernel 2.6.18 it works as inteded.
On oraclelinux with kernel 2.6.39 there is always a critical alarming shown but in real the cpu usage is always below 10%. It seems that there isn't checked against cpu used anymore but against cpu free.
CRITICAL - 2 CPU cores - CPU(all) 95.0% used > 90%, CPU0 97.0% used > 90%, CPU1 93.0% used > 90%
-> but CPU usage is very low
So something changed in the kernel version between 2.6.18 and 2.6.39 in relation to /proc/stat
I had a small look at the changelog of those kernels and found a possible reason for this issue in kenel uupdate 2.6.37 at "Memory management":
/proc/stat: Make reading /proc/stat scalable (commit), fix scalability of irq sum of all cpu (commit)
On oraclelinux with kernel 2.6.18 it works as inteded. On oraclelinux with kernel 2.6.39 there is always a critical alarming shown but in real the cpu usage is always below 10%. It seems that there isn't checked against cpu used anymore but against cpu free.
CRITICAL - 2 CPU cores - CPU(all) 95.0% used > 90%, CPU0 97.0% used > 90%, CPU1 93.0% used > 90% -> but CPU usage is very low
So something changed in the kernel version between 2.6.18 and 2.6.39 in relation to /proc/stat
I had a small look at the changelog of those kernels and found a possible reason for this issue in kenel uupdate 2.6.37 at "Memory management": /proc/stat: Make reading /proc/stat scalable (commit), fix scalability of irq sum of all cpu (commit)
Please have a look at: http://kernelnewbies.org/Linux_2_6_37
Feel free to contact me for testing!