Hi Roman,
On Sat, Mar 28, 2009 at 4:40 PM, Roman Pearce <rpear...@gmail.com> wrote:
>
> /* Linux */
> #include <sched.h>
> int sched_getaffinity(pid_t pid, unsigned int cpusetsize, cpu_set_t
> *mask);
>
> static inline int num_processors()
> {
> unsigned int bit;
> int np;
> cpu_set_t aff;
> memset(&aff, 0, sizeof(aff) );
> sched_getaffinity(0, sizeof(aff), &aff );
> for(np = 0, bit = 0; bit < 8*sizeof(aff); bit++)
> np += (((char *)&aff)[bit / 8] >> (bit % 8)) & 1;
> return np;
> }
>
>
> /* Mac OS X */
> #include <sys/types.h>
> #include <sys/sysctl.h>
> static inline int num_processors()
> {
> int np = 1;
> size_t length = sizeof( np );
> sysctlbyname("hw.ncpu", &np, &length, NULL, 0);
> return np;
> }
>
>
> /* Windows NT */
> #include <windows.h>
> static inline int num_processors()
> {
> SYSTEM_INFO info;
> GetSystemInfo(&info);
> return info.dwNumberOfProcessors;
> }
Thanks a lot for the code!
I just tried the following code on several linuxes (Debian, Ubuntu,
Gentoo, Red Hat, OpenSUSE) and on OS X 10.5 Intel and it seems to just
work everywhere:
#include "unistd.h"
#include "stdio.h"
int main()
{
int ncpus;
ncpus = sysconf(_SC_NPROCESSORS_ONLN);
printf("%d", ncpus);
return 0;
}
It will not work on windows, but is there some reason to use a
different code for linux and Mac, if the above seems to be working
just fine?
Ondrej
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