How to get total cpu usage in Linux using C++

by

cat /proc/stat

http://www.linuxhowtos.org/System/procstat.htm

I agree with this answer above. The cpu line in this file gives the total number of “jiffies” your system has spent doing different types of processing.

What you need to do is take 2 readings of this file, seperated by whatever interval of time you require. The numbers are increasing values (subject to integer rollover) so to get the %cpu you need to calculate how many jiffies have elapsed over your interval, versus how many jiffies were spend doing work.

e.g.
Suppose at 14:00:00 you have

cpu 4698 591 262 8953 916 449 531

total_jiffies_1 = (sum of all values) = 16400

work_jiffies_1 = (sum of user,nice,system = the first 3 values) = 5551

and at 14:00:05 you have

cpu 4739 591 289 9961 936 449 541

total_jiffies_2 = 17506

work_jiffies_2 = 5619

So the %cpu usage over this period is:

work_over_period = work_jiffies_2 – work_jiffies_1 = 68

total_over_period = total_jiffies_2 – total_jiffies_1 = 1106

%cpu = work_over_period / total_over_period * 100 = 6.1%

Hope that helps a bit.

More Related Contents:

  1. some problems about c++ try catch [closed]
  2. How do I find the location of the executable in C? [duplicate]
  3. print call stack in C or C++
  4. C++ Dynamic Shared Library on Linux
  5. How to get memory usage at runtime using C++?
  6. How can I create directory tree in C++/Linux?
  7. How to create a single instance application in C or C++
  8. C++ standard library and Boehm garbage collector
  9. Get the compiler options from a compiled executable?
  10. Send and Receive a file in socket programming in Linux with C/C++ (GCC/G++)
  11. Is it safe to fork from within a thread?
  12. Seeking and reading large files in a Linux C++ application
  13. How to disassemble a binary executable in Linux to get the assembly code?
  14. Cancelling a thread using pthread_cancel : good practice or bad
  15. Linking libstdc++ statically: any gotchas?
  16. Why does the library linker flag sometimes have to go at the end using GCC?
  17. How to set up googleTest as a shared library on Linux
  18. Linking g++ 4.8 to libstdc++
  19. How to pretty-print STL containers in GDB?
  20. Could you recommend some guides about Epoll on Linux [closed]
  21. C and C++ programming on Ubuntu 11.10 [closed]
  22. “relocation R_X86_64_32S against ” linking Error
  23. Linux c++ error: undefined reference to ‘dlopen’
  24. How to fix: /usr/lib/libstdc++.so.6: version `GLIBCXX_3.4.15′ not found
  25. version `CXXABI_1.3.8′ not found (required by …) [duplicate]
  26. Exception running boost asio ssl example
  27. Find available network interfaces in C/C++? [closed]
  28. Check keypress in C++ on Linux
  29. How to get the username in C/C++ in Linux?
  30. How to assert if a std::mutex is locked?

Leave a Comment