在Linux上,使用它可能并不安全,_SC_NPROCESSORS_ONLN
因为它不是POSIX标准的一部分,并且sysconf手册对此进行了说明。因此,有_SC_NPROCESSORS_ONLN
可能不存在:
These values also exist, but may not be standard.
[...]
- _SC_NPROCESSORS_CONF
The number of processors configured.
- _SC_NPROCESSORS_ONLN
The number of processors currently online (available).
一种简单的方法是读取/proc/stat
或/proc/cpuinfo
计数它们:
#include<unistd.h>
#include<stdio.h>
int main(void)
{
char str[256];
int procCount = -1; // to offset for the first entry
FILE *fp;
if( (fp = fopen("/proc/stat", "r")) )
{
while(fgets(str, sizeof str, fp))
if( !memcmp(str, "cpu", 3) ) procCount++;
}
if ( procCount == -1)
{
printf("Unable to get proc count. Defaulting to 2");
procCount=2;
}
printf("Proc Count:%d\n", procCount);
return 0;
}
使用/proc/cpuinfo
:
#include<unistd.h>
#include<stdio.h>
int main(void)
{
char str[256];
int procCount = 0;
FILE *fp;
if( (fp = fopen("/proc/cpuinfo", "r")) )
{
while(fgets(str, sizeof str, fp))
if( !memcmp(str, "processor", 9) ) procCount++;
}
if ( !procCount )
{
printf("Unable to get proc count. Defaulting to 2");
procCount=2;
}
printf("Proc Count:%d\n", procCount);
return 0;
}
在外壳中使用grep的相同方法:
grep -c ^processor /proc/cpuinfo
要么
grep -c ^cpu /proc/stat # subtract 1 from the result