Originally posted by: SystemAdmin

// --- OS ---
AIX ep5710g 3 5

// --- Compiler ---
IBM XL C/C++ Enterprise Edition V8.0 for AIX
Version: 08.00.0000.0014

// --- Calling the prtconf command
> prtconf | grep Processors
Number Of Processors: 16

// --- User program foo.cpp ----
#include <iostream>
#include <unistd.h>
#include <sys/systemcfg.h>

int main()
{

//

---

// SC_NPROCESSORS_CONF Number of processors configured.
std::cout << "_SC_NPROCESSORS_CONF\t ="
<< sysconf(_SC_NPROCESSORS_CONF)
<< std::endl;

//

---

// _SC_NPROCESSORS_ONLN Number of processors online
std::cout << "_SC_NPROCESSORS_ONLN\t ="
<< sysconf(_SC_NPROCESSORS_ONLN)
<< std::endl;

//

---

// ncpus Identifies the number of CPUs active on a machine.
// Uniprocessor (UP) machines are identified by a 1.
// Values greater than 1 indicate multiprocessor (MP) machines.
std::cout << "_system_configuration.ncpus\t ="
<< _system_configuration.ncpus
<< std::endl;
return 0;
}
//

---

> xlC_r foo.cpp

> ./a.out
_SC_NPROCESSORS_CONF =*32*
_SC_NPROCESSORS_ONLN =*32*
_system_configuration.ncpus =*32*
It seems that number of proceesors produced by prtconf and sysconf() are inconsistent.

Thanks,

Alex Vinokur
#AIX-Forum

Originally posted by: flodstrom

Although I still find it somewhat confusing with regards to IBM and their definition of processors, CPU's, etc., but the numbers you see are most likely correct. This is due to the fact that SMT most likely is enabled, which in your case means that AIX see's 32 CPU's (2 SMT threads/processor).

For example, you can check if SMT is enabled with this command:

lsattr -E -l proc0
#AIX-Forum