From: Robert Klemme <shortcutter@...>
Date: 2008-12-14T23:17:50+09:00
Subject: Re: Get CPU usage

On 14.12.2008 14:01, Panda Beer wrote:
> Hello everybody,
> 
> I would like to get the % of CPU usage of a current Ruby script.
> For example, I would like to start my script like and allow it to get
> and print this such as:
> 
> /application.rb
> => 12:10 => CPU usage is 3.2%
> => 12:15 => CPU usage is 3.1%
> => 12:20 => CPU usage is 3.1%
> => 12:25 => CPU usage is 3.5%
> 
> Have you got an idea? Many thanks.

$ ruby -e '10.times { 100000.times { 1 + 2 }; p Process.times }'
#<struct Struct::Tms utime=0.062, stime=0.046, cutime=0.0, cstime=0.0>
#<struct Struct::Tms utime=0.109, stime=0.046, cutime=0.0, cstime=0.0>
#<struct Struct::Tms utime=0.156, stime=0.046, cutime=0.0, cstime=0.0>
#<struct Struct::Tms utime=0.203, stime=0.046, cutime=0.0, cstime=0.0>
#<struct Struct::Tms utime=0.25, stime=0.046, cutime=0.0, cstime=0.0>
#<struct Struct::Tms utime=0.296, stime=0.046, cutime=0.0, cstime=0.0>
#<struct Struct::Tms utime=0.343, stime=0.046, cutime=0.0, cstime=0.0>
#<struct Struct::Tms utime=0.406, stime=0.046, cutime=0.0, cstime=0.0>
#<struct Struct::Tms utime=0.453, stime=0.046, cutime=0.0, cstime=0.0>
#<struct Struct::Tms utime=0.5, stime=0.046, cutime=0.0, cstime=0.0>

You could correlate that to real time that has passed.

$ ruby -e 't=Time.now; 10.times { sleep 2; 
pt=Process.times;p((pt.utime+pt.stime)/(Time.now-t)) }'
0.015
0.00749812546863284
0.00499916680553241
0.00374953130858643
0.002999700029997
0.00249979168402633
0.00214270409256482
0.00187488281982376
0.00166657407921782
0.00149992500374981

robert@fussel ~
$ ruby -e 't=Time.now; 10.times {10_000.times {1+2}; 
pt=Process.times;p((pt.utime+pt.stime)/(Time.now-t)) }'
19.25
8.55555555555556
5.13333333333333
4.89473684210526
3.875
3.20689655172414
3.20588235294118
2.86842105263158
2.5952380952381
2.31914893617021

Obviously there is a factor missing...

robert@fussel ~

	robert