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Cpu usage in the output of top

Cpu usage in the output of top

I am looking at the output of top.

Asked by: Guest | Views: 31
Total answers/comments: 1
Guest [Entry]

"First, a couple of sources:
* Top: Linux Command,
* nice article on top usage patterns.

(1) is ""us"" part in the third line
same as ""load average/number of cores""
or something I heard people mentioned
""CPU utilization""?

the ""us"" field shows CPU Time in User Mode. See CPU Modes.

What are ""processes that are not
niced""?

A process ""niceness"" is an internal numeric value that essentially defines how nice a process is being to the CPU. A low priority process, that sleeps and takes very few processing power (cycles) when active is a ""nice"" process.
Niceness can be positive or negative. A negative niceness is a process that is demanding more priority and taking more cycles. Not nice at all. A positive niceness is a process taking few cycles, sleeping most of the time and having low priority. Very nice. See Nice.

So the ""us"" field shows you how much CPU time the negative niceness (the not nice) user mode processes are taking. To see the ""niced"" processes look at the ""ni"" field.

(3) some says ""CPU utilization"" is a
better measurement than load average.
So how to get ""CPU utilization""? If I
sum up the %CPU column for all
processes, is that ""CPU utilization""
or something else different than ""CPU
utilization * number of cores"" and
load average?

To see the CPU utilization, look at the ""id"" field. This is the idle time. CPU utilization is thus, 100 - id."