mikeb01

public class PopCntBenchmark extends SimpleBenchmark
{
    public int timeIntegerBitCount(int iterations)
    {
        int result = 0;
        for (int i = 0; i < iterations; i++)
        {
            result += Integer.bitCount(i);
        }
        return result;

mikeb01

popcnt %r11d,%ebx
add    0x8(%rsi),%ebx     ;*iadd
                          ; - PopCntTest::main@12 (line 9)
  

mikeb01

mov    %r11d,%r8d
shr    %r8d
and    $0x55555555,%r8d
sub    %r8d,%r11d         ;*isub
                          ; - java.lang.Integer::bitCount@7 (line 1143)
                          ; - PopCntTest::main@9 (line 9)
mov    %r11d,%r8d
shr    $0x2,%r8d
and    $0x33333333,%r11d
and    $0x33333333,%r8d

mikeb01

public final class Integer
{
    public static int bitCount(int i)
    {
        // HD, Figure 5-2
        i = i - ((i >>> 1) & 0x55555555);
        i = (i & 0x33333333) + ((i >>> 2) & 0x33333333);
        i = (i + (i >>> 4)) & 0x0f0f0f0f;
        i = i + (i >>> 8);
        i = i + (i >>> 16);

mikeb01

public class PopCntTest
{
    public static void main(String[] args)
    {
        int result = 0;
        for (int i = 0; i < 1000000000; i++)
        {
            result += Integer.bitCount(i);
        }
        

mikeb01

package com.lmax.disruptor;

import java.util.concurrent.BrokenBarrierException;
import java.util.concurrent.CyclicBarrier;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

import org.junit.Test;

mikeb01

extern "C" {
/* from sys/osfmk/i386/mp.c */

extern void mp_rendezvous(void (*setup_func)(void *),
                          void (*action_func)(void *),
                          void (*teardown_func)(void *),
                          void *arg);

extern int cpu_number(void);
}

mikeb01

#include <stdio.h>

static void cpuid(int op1, int op2, int *data) {
    asm("cpuid" 
        : "=a" (data[0]), "=b" (data[1]), "=c" (data[2]), "=d" (data[3])
        : "a"(op1), "c"(op2));
}

int main (int argc, const char * argv[]) {
    int values[4];

mikeb01

#include <stdio.h>

static void cpuid(int op1, int op2, int *data) {
    asm("cpuid" 
        : "=a" (data[0]), "=b" (data[1]), "=c" (data[3]), "=d" (data[2])
        : "a"(op1), "c"(op2));
}

int main(int argc, char** argv) {
    int values[5];

mikeb01

public void serialisePublishing(final long sequence,
                                final Sequence cursor,
                                final int batchSize) {

    // Guard condition, limit the number of pending publications
    int counter = RETRIES;
    while (sequence - cursor.get() > pendingPublication.length()) {
        if (--counter == 0) {
            Thread.yield();
            counter = RETRIES;