alloc_cost.m

/*
 * compare [NSObject alloc] with malloc(sizeof(NSObject))
 *
 * build:
 *   cc -Wall -g -framework Foundation alloc_cost.m
 *
 * result:
 *   % ./a.out
 *     sizeof(NSObject)=4
 *     elapsed time of [NSObject alloc] = 0.235727
 *     elapsed time of malloc(sizeof(NSObject)) = 0.073298
 *   on MacBook C2D.
 *
 *   => malloc seems to be 3 times faster,
        though NSObject would be very sophisticated and
        sizeof(NSObject) may not be the correct metrix.
 *
 */

#include <stdio.h>
#include <sys/time.h>
#import <Foundation/Foundation.h>
#define LOOP_COUNT (1024 * 1024)
#define START_TIMER gettimeofday(&start, NULL);
#define STOP_TIMER  gettimeofday(&stop, NULL);

long elapsed(struct timeval *start, struct timeval *stop) {
  return (stop->tv_sec * 1000000 + stop->tv_usec) -
    (start->tv_sec * 1000000 + start->tv_usec);
}

int main(int argc, char *argv[])
{
  NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];

  int i;
  struct timeval start, stop;

  printf("sizeof(NSObject)=%ld\n", sizeof(NSObject));

  START_TIMER;
  for (i=0; i<LOOP_COUNT; i++) {
    NSObject *obj = [NSObject alloc];
  }
  STOP_TIMER;

  printf("elapsed time of [NSObject alloc] = %f\n", (float)elapsed(&start, &stop) / LOOP_COUNT);

  START_TIMER;
  for (i=0; i<LOOP_COUNT; i++) {
    void *obj = malloc(sizeof(NSObject));
  }
  STOP_TIMER;


  printf("elapsed time of malloc(sizeof(NSObject)) = %f\n", (float)elapsed(&start, &stop) / LOOP_COUNT);

  [pool release];
  return 0;
}