How to Determine Cpu and Memory Consumption from Inside a Process

Measure CPU/memory consumption

To calculate the percentage of the used CPU, you can use Alexsis Wilke advice for using getrusage() and divide by the total runtime as you calculated in your question.
This will give you the average percentage of the used CPU for a single CPU. If you are using many processors, you can also divide by the number of processors.

Tracking CPU and Memory usage per process

Press Win+R, type perfmon and press Enter. When the Performance window is open, click on the + sign to add new counters to the graph. The counters are different aspects of how your PC works and are grouped by similarity into groups called "Performance Object".

For your questions, you can choose the "Process", "Memory" and "Processor" performance objects. You then can see these counters in real time

You can also specify the utility to save the performance data for your inspection later. To do this, select "Performance Logs and Alerts" in the left-hand panel. (It's right under the System Monitor console which provides us with the above mentioned counters. If it is not there, click "File" > "Add/remove snap-in", click Add and select "Performance Logs and Alerts" in the list".) From the "Performance Logs and Alerts", create a new monitoring configuration under "Counter Logs". Then you can add the counters, specify the sampling rate, the log format (binary or plain text) and log location.

C++: Measuring memory usage from within the program, Windows and Linux [duplicate]

To know how much physical memory your process takes you need to query the process working set or, more likely, the private working set. The working set is (more or less) the amount of physical pages in RAM your process uses. Private working set excludes shared memory.

See

• What is private bytes, virtual bytes, working set?
• How to interpret Windows Task Manager?
• https://blogs.msdn.microsoft.com/tims/2010/10/29/pdc10-mysteries-of-windows-memory-management-revealed-part-two/

for terminology and a little bit more details.

There are performance counters for both metrics.

(You can also use QueryWorkingSet(Ex) and calculate that on your own, but that's just nasty in my opinion. You can get the (non-private) working set with GetProcessMemoryInfo.)

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But the more interesting question is whether or not this helps your program to make useful decisions. If nobody's asking for memory or using it, the mere fact that you're using most of the physical memory is of no interest. Or are you worried about your program alone using too much memory?

You haven't said anything about the algorithms it employs or its memory usage patterns. If it uses lots of memory, but does this mostly sequentially, and comes back to old memory relatively rarely it might not be a problem. Windows writes "old" pages to disk eagerly, before paging out resident pages is completely necessary to supply demand for physical memory. If everything goes well, reusing these already written to disk pages for something else is really cheap.

If your real concern is memory thrashing ("virtual memory will be of no use due to swapping overhead"), then this is what you should be looking for, rather than trying to infer (or guess...) that from the amount of physical memory used. A more useful metric would be page faults per unit of time. It just so happens that there are performance counters for this too. See, for example Evaluating Memory and Cache Usage.

I suspect this to be a better metric to base your decision on.

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