top for long time, albeit basically, I have grown to distrust its
% CPU column reports. I have an 8-core (quad core Intel i7 920 with hyperthreading) hardware, and see some wild numbers when running a process that should not use more than 5% overall.
top happily reports 50%, and I suspect it is not so.
My question is, is it a known fact that it's inaccurate when several CPUs/cores are present?
mpstat from the
sysstat package, and its showings are much more conservative, certainly within my expectations. I did press
top to switch it to show all the core and us/sy/io stats, but the numbers are substantially higher than with
I know that my expectations could be unfounded as well, but my gut feeling tells me
top is wrong!
The reason I need to know is because the process I am monitoring only guarantees quality of service with CPU usage "less than 80%" (however vague that sounds), and I need to know how much headroom I have left. It's a streaming server.