I've seen the CPU usage go over 100%. How is this possible? Is it because I have four CPU cores, so 100% isn't really the max?
Also, when a program does this, what else can I do in top besides using the
AFAIK top shows the CPU usage in relation to the power of 1 core, i.e if your task takes up 200% CPU then it's occupying two cores.
From the top man-page
k: %CPU -- CPU usage The task's share of the elapsed CPU time since the last screen update, expressed as a percentage of total CPU time. In a true SMP environment, if 'Irix mode' is Off, top will operate in number of CPUs. You toggle 'Irix/Solaris' modes with the 'I' interactive com- mand.
So, yes, top shows CPU percentage PER core, but you can toggle this behaviour be pressing 'I'.
Yes, if a process in top goes over 100% or top shows >1.0 in load, this means that more than one core is occupied, or the system is oversubscribed. Oversubscription means that there is more work to be put onto the core than is phsyically manageble.
top you can also sort the view by different parameters (like used memory). If you want to look what you can sort by, refer to the help or man page for
You can also see all kind of information about the processes themselves, like Virtual or resident memory used by the process and if it's sleeping or currently running, as well as cpu time used.
The load average in the top, if needed, can also be viewed by the