int
ci_get_cpu_khz(unsigned* cpu_khz_out)
{
FILE* f;
char buf[80];
if( ! ci_cpu_khz ) {
/* We only go get the khz if we need to. Obviously it's sensible for
* performance, but also we need to do this because we can't call fclose
* once the system is fully initialized, since our overridden version of
* fclose needs to get the fdtable-lock. (Note: we would ideally just
* ensure we always call the 'real' libc fclose from here, but since this
* gets linked into the ciapp library, finding real libc is not so easy)
* Therefore, it is important that this function get called early, to
* ensure that we can't deadlock on ourselves by calling fclose when the
* fdtable lock is held.
*/
f = fopen("/proc/cpuinfo", "r");
if( !f ) return -errno;
while( 1 ) {
if( !fgets(buf, sizeof(buf), f) ) {
fclose (f);
return -EIO;
}
if( try_get_hz(buf, &ci_cpu_khz) ) break;
}
fclose (f);
}
if( cpu_khz_out ) *cpu_khz_out = ci_cpu_khz;
return 0;
}
int
ci_get_cpu_khz(unsigned* cpu_khz_out)
{
FILE* f;
char buf[80];
if( ! ci_cpu_khz ) {
/* On powerpc /proc/cpuinfo gives reliable information, hence no need to
* measure.
* On x86 cpuinfo readings might be ugely inaccurate when cpu_scaling
* is enabled */
#ifndef __powerpc__
if( ci_measure_cpu_khz(&ci_cpu_khz) )
goto end;
else
ci_log("Warning measured cpu_khz not stable, querying /proc/cpuinfo");
#endif
/* We only go get the khz if we need to. Obviously it's sensible for
* performance, but also we need to do this because we can't call fclose
* once the system is fully initialized, since our overridden version of
* fclose needs to get the fdtable-lock. (Note: we would ideally just
* ensure we always call the 'real' libc fclose from here, but since this
* gets linked into the ciapp library, finding real libc is not so easy)
* Therefore, it is important that this function get called early, to
* ensure that we can't deadlock on ourselves by calling fclose when the
* fdtable lock is held.
*/
f = fopen("/proc/cpuinfo", "r");
if( !f ) return -errno;
while( 1 ) {
if( !fgets(buf, sizeof(buf), f) ) {
fclose (f);
return -EIO;
}
if( try_get_hz(buf, &ci_cpu_khz) ) break;
}
fclose (f);
}
#ifndef __powerpc__
end:
#endif
if( cpu_khz_out ) *cpu_khz_out = ci_cpu_khz;
return 0;
}
