How can I get instant CPU load values?

Question

I have made a server-client application in which based on CPU usage and load conditions it serves a file request to user.

I am using /proc/loadavg values for this . But this utility gives values averaged out over at least 1 minute.

I want values averaged out over much lesser time like 1 second or 5 seconds.

Answer 1

How about parsing the output from mpstat from the sysstat package? You can get statistics for each processor and set the interval (below is for 2s interval).

Sample output:

$ mpstat -P ALL 2
Linux 3.5.0-19-generic (ubuntu)     11/30/2012  _x86_64_    (4 CPU)

08:34:28 AM  CPU    %usr   %nice    %sys %iowait    %irq   %soft  %steal  %guest   %idle
08:34:30 AM  all    1.01    0.00    1.26    0.00    0.00    0.13    0.00    0.00   97.61
08:34:30 AM    0    2.50    0.00    1.50    0.00    0.00    0.50    0.00    0.00   95.50
08:34:30 AM    1    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00  100.00
08:34:30 AM    2    1.01    0.00    3.02    0.00    0.00    0.00    0.00    0.00   95.98
08:34:30 AM    3    0.50    0.00    0.50    0.00    0.00    0.00    0.00    0.00   99.00

Alternatively, you could implement the algorithm yourself. Take a look here and here.

Another way to do it would be to monitor the difference in idle time vs other usage time in /proc/stat at defined time interval and calculate the load based on that. Here's more info on /proc/stat.