Resource Usage Library

This is a statically linkable version of the GNU Time program. Much of the code is ported from that project. You can find more informaiton about the GNU Time project at [[http://directory.fsf.org/wiki/Time]].

Usage

This library can be used in two ways. It can be used to track resources used by the entire process in much the same way as GNU Time. It can also be used to track resource usage of single threads.

Process Resources

To track the resources used by a process create a variable of type struct resuse and pass that to the resuse_start() function with the scope set to RESUSE_SCOPE_PROC. At the point that you want to collect resources at use the function resuse_end() passing in the same resuse object.

Example

int main(int argc, char * argv[]){
	struct resuse resuse;
	resuse_start(&resuse, RESUSE_SCOPE_PROC);
	
	// ...
	
	resuse_end(&resuse);
	
	// ...
}

Thread Resources

To track the resources used by a single thread follow the same directions as for a process, but change the scope to RESUSE_SCOPE_THREAD. Note that to collect thread resources _GNU_SOURCE must be defined.

Example

void * thread(void* param){
	struct resuse resuse;
	resuse_start(&resuse, RESUSE_SCOPE_THREAD);
	
	// ...
	
	resuse_end(&resuse);
	
	// ...
}

Printing Ouput

After collecting the resource data libresuse provides resuse_fprint() which will format and print the results. resuse_fprint() takes as a parameter a format string which works similarly to printf(). It uses % followed by a unique character that will be expanded into the correct resource information.

Recognized commands

This is a list of commands that resuse_fprintf() recognizes.

• % == A literal `%'
• D == Average unshared data size in KB
• E == Elapsed real (wall clock) time in [hour:]min:sec
• F == major page faults (required physical I/O)
• I == File system inputs
• K == Average total mem usage
• M == Maximum resident set size in KB
• O == File system outputs
• P == Percent of CPU this job got
• R == Minor page faults
• S == System (kernel) time
• U == User time
• W == Times swapped out
• X == Average amount of shared text in KB
• Z == Page size
• c == Involuntary context switches
• e == Elapsed real time in seconds
• k == Signals delivered
• p == Average unshared stack size in KB
• r == Socket messages received
• s == Socket messages sent
• t == Average resident set size in KB
• w == Voluntary context switches

Example

Printing the real, user, and system time a process existed:

resuse_fprint(stdout, "Real Time: %E, User Time: %U, System Time: %S, CPU Usage: %P\n", &resuse);