How can I measure CPU time of a specific set of threads?

I run C++ program in Linux.

There are several threads pool (for computation, for io, for … such things).

The system call clock() gives me a way to measure the CPU time spent by all the CPU cores for the process.

However, I want to measure the CPU time spent only by the threads in the computation threads pool.

How can I achieve it?

Thanks 😀

Answer

To get CPU clock ID of every thread you can use: pthread_getcpuclockid and using this CPU clock ID you can retrieve the current thread CPU time using: clock_gettime.

Following is the sample code to demonstrate the same:

struct timespec currTime;
clockid_t threadClockId;

//! Get thread clock Id
pthread_getcpuclockid(pthread_self(), &threadClockId);
//! Using thread clock Id get the clock time
clock_gettime(threadClockId, &currTime);