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performancecpucpu-usageramqnx
Boernii
Boernii

Reputation: 131

How to get CPU load / RAM usage out of QNX?

I'm currently trying to get information about the CPU load and RAM usage out of an PowerPC with QNX running on it. The idea is to write that information in a text file with a time stamp over a certain amount of time, but this ain't my problem here once I have the information as a "standard value". My programm will be in C++ and I already did this kind of program for Windows (via PDH API). Maybe you have page like this but for QNX? Probably I'm looking for the wrong keywords.

Can you help me with this problem? Any kind of direction would be most welcome as I'm new to QNX and this kind of programming. Thanks a lot!

Upvotes: 1

Views: 14434

Answers (1)

maverick
maverick

Reputation: 436

You will work with the /proc filesystem.

  1. From the command line you can check the size of the memory space of the process that has process ID = 1234 by:

ls -l /proc/1234/as

"as" stands for "address space" and the size of this virtual file will indicate a good estimate of the memory used by the process in question, 1236992 bytes in this example:

-rw-r--r-- 1 root root 1236992 Aug 21 21:25 as

To get the same value programmatically you will need to use the stat() function on the /proc/PID/as file.

You can refer the following page in the documentation for a more detailed explanation of the same: http://www.qnx.com/developers/docs/660/index.jsp?topic=%2Fcom.qnx.doc.neutrino.cookbook%2Ftopic%2Fs3_procfs_pid_directories.html

  1. In order to get the CPU time (system/user) used by the process you can use the DCMD_PROC_INFO devctly() on the /proc/PID/as file. You will need to refer the "utime" and "stime" members of the debug_process_t structure passed to the devctl().

You can find a detailed explanation and sample code on the following page in the QNX documentation: http://www.qnx.com/developers/docs/660/index.jsp?topic=%2Fcom.qnx.doc.neutrino.cookbook%2Ftopic%2Fs3_procfs_DCMD_PROC_INFO.html

Upvotes: 3

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