RFR: os::processor_id() for Mac OS X

[Gerard Ziemski]

hi all,

Please review this simple feature adding os::processor_id() implementation for Mac OS X:

http://cr.openjdk.java.net/~gziemski/zgc_os_processor_id/webrev/src/hotspot/os/bsd/os_bsd.cpp.udiff.html <http://cr.openjdk.java.net/~gziemski/zgc_os_processor_id/webrev/src/hotspot/os/bsd/os_bsd.cpp.udiff.html>

Here is a standalone test using such implementation:

#include <stdio.h>
#include <unistd.h>
#include <cpuid.h>
#include <pthread.h>

int get_cpu_id() {
  uint32_t EAX = 0; // must be set to 0
  uint32_t EBX = 0;
  uint32_t ECX = 0;
  uint32_t EDX = 0;
  __cpuid(1, EAX, EBX, ECX, EDX);
  // Check EDX for Advanced Programmable Interrupt Controller
  if ((EDX & bit_APIC) != 0) {
    // EBX[bits 31:24] Local APIC ID: The initial APIC-ID is used to identify the executing logical processor.
    return (EBX >> 24) & 0xFF;
  }
  return 0;
}

void *tick(void *void_ptr)
{
  int thread_id = *((int *)void_ptr);
  for (int i=0; i<10; i++) {
    printf("thread: %2d running on cpu: %d\n", thread_id, get_cpu_id());
    sleep(1);
  }
  return NULL;
}

int main(int argc, const char * argv[]) {
  int count = 32;
  pthread_t thread[count];
  for (int i=0; i<count; i++) {
    pthread_create(&thread[i], NULL, tick, &i);
  }
  for (int i=0; i<count; i++) {
    pthread_join(thread[i], NULL);
  }
  return 0;
}

-------------------------------------------
Outputs:

thread:  2 running on cpu: 4
thread:  3 running on cpu: 5
thread:  4 running on cpu: 2
thread:  6 running on cpu: 1
thread:  6 running on cpu: 5
thread:  7 running on cpu: 1
thread:  8 running on cpu: 7
thread:  9 running on cpu: 5
thread:  9 running on cpu: 7
thread: 10 running on cpu: 3
thread: 11 running on cpu: 3
thread: 12 running on cpu: 2
thread: 13 running on cpu: 3
thread: 15 running on cpu: 1
thread: 16 running on cpu: 3
thread: 17 running on cpu: 7
thread: 18 running on cpu: 3
thread: 19 running on cpu: 5
thread: 19 running on cpu: 2
thread: 21 running on cpu: 2
thread: 22 running on cpu: 7
…

cheers