Question

I need to measure, in C++ on Linux (and other Unix-like systems), the CPU (not wall clock) time taken by a long computation, so I’m using clock(). Problem: on 32 bit systems, this wraps around after about 2000 or 4000 seconds.

What’s the recommended workaround for this?

Answer 1

You want to use getrusage which fills the following struct:

struct rusage {     struct timeval ru_utime; /* user time used */     struct timeval ru_stime; /* system time used */     ... }; 

For completion, struct timeval:

struct timeval {     time_t      tv_sec;     /* seconds */     suseconds_t tv_usec;    /* microseconds */ }; 

As always, consult the manpage for details (man getrusage)