Portable way to get system/process information

[lh3]

The wtdbg2 algorithm is largely OS-independent. However, to collect system and process information, it assumes the OS is Linux. It would be good remove this dependency. Here are some portable ways to get the real time, CPU time and peak RAM of the current process, and the number of CPUs and total RAM of the system. These work for Mac and Linux.

#include <sys/resource.h>
#include <sys/time.h>
#include <time.h>
#include <unistd.h>

double cputime(void) // return in CPU seconds, including both user and system CPU time
{
	struct rusage r;
	getrusage(RUSAGE_SELF, &r);
	return r.ru_utime.tv_sec + r.ru_stime.tv_sec + 1e-6 * (r.ru_utime.tv_usec + r.ru_stime.tv_usec);
}

double realtime(void) // return in seconds
{
	struct timeval tp;
	struct timezone tzp;
	gettimeofday(&tp, &tzp);
	return tp.tv_sec + tp.tv_usec * 1e-6;
}

long peakrss(void) // return in bytes
{
	struct rusage r;
	getrusage(RUSAGE_SELF, &r);
#ifdef __linux__
	return r.ru_maxrss * 1024;
#else
	return r.ru_maxrss;
#endif
}

int ncpucore(void)
{
	return sysconf(_SC_NPROCESSORS_ONLN);
}

long totalmem(void) // return in bytes
{
	long pages = sysconf(_SC_PHYS_PAGES);
	long page_size = sysconf(_SC_PAGE_SIZE);
	return pages * page_size;
}

#include <stdio.h>
#include <stdlib.h>

int main(void)
{
	int i, n = 1<<20, *p;
	p = (int*)calloc(n, sizeof(int));
	for (i = 0; i < n; ++i) p[i] = i;
	fprintf(stderr, "ncpu: %d\n", ncpucore());
	fprintf(stderr, "peakrss: %ld\n", peakrss());
	fprintf(stderr, "totalmem: %ld\n", totalmem());
	return 0;
}

[lh3]

PS: it is not necessary to make changes now. These functions are just something that might be useful in future.

[ruanjue]

Thanks, Heng.

mem_share.h is a patchwork, will be split into multiple header files according function.