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metaylor
10th April 2009, 05:59 PM
I have three questions regarding the System Monitor Information.

First, question is can anyone tell me when the information displayed on the System tab of System monitor is collected? Is it being collected during the boot process, log on process or when System Monitor is launched?

Second question is whether the cpuinfo or cpuid commands are used to gather this information? If not what commands are used?

Third question is whethe these commands are executed via some service or process and if so, which?

stlouis
11th April 2009, 03:33 AM
First off, your "proc tables" stores information about your kernels current state, like cpu, disk, network, memory, etc...

If you go to your /proc directory, you may cat or vi the files, to see current information. You may have to navigate to subdirectories to gather certain information.

Second, take a look at this article. It explains how to get statistical cpu information, using tools such as top, sar and mpstat. very powerful

http://www.cyberciti.biz/tips/how-do-i-find-out-linux-cpu-utilization.html

Here's another good article on command-line tools you may find useful;

http://www.unixguide.net/linux/linuxshortcuts.shtml

Last but not least, the above should answer this question as well.

metaylor
12th April 2009, 05:57 AM
Thanks for the information I can use it.

However, I am actually trying to understand at what point CPU information is gathered. The reason is I have a program that reads the CPU speed for Intel CPUs from the CPU registers. I can run the program from a terminal and from an ICON on the desktop.

I have a particular senario in which I run the program from the ICON then log off. Because I set the session to remember current session at logout the effect is the program automatically runs the next time I log on. However, the CPU speed values are higher than than are seen when I run the program manually from terminal or double-clicking ICON.

In trying to understand this, I ran the program manually and while it is running I launch system monitor and check system tab and I have observed that the progarm reports an increase in the value of the CPU speed.

If I add a "sleep 10" to the script that runs the program then the CPU speed values are the same regardless of whether I run manually, or whether the program is run automatically at login.

My theory is that the system monior (or something else) is using the CPUInfo and/or CPUID command which results in this but I am not sure if this is valid theory.

I hope this additional info is helpful