#include <stdio.h>
#include <sys/time.h>
#include <stdlib.h>
#include <sys/mman.h>

// Testing on Mid-2014 MacBook Pro:

// OSX                                   : $ gcc -O0 -std=c99 -o mlock-test mlock-test.c && ./mlock-test
// OSX                                   : - mlock_status 0
// OSX                                   : - elapsed_without_mlock 0.003493 seconds
// OSX                                   : - elapsed_with____mlock 0.027737 seconds (7.9 times slower), average per mlock() 0.000000 seconds

// Testing OS on VMware Workstation on OSX on Mid-2014 MacBook Pro:

// Ubuntu 14.04                          : $ gcc -O0 -std=c99 -o mlock-test mlock-test.c && ./mlock-test
// Ubuntu 14.04                          : - mlock_status -99039
// Ubuntu 14.04                          : - elapsed_without_mlock 0.003451 seconds
// Ubuntu 14.04                          : - elapsed_with____mlock 0.015507 seconds (4.5 times slower), average per mlock() 0.000000 seconds

// CentOS 6.6                            : $ gcc -O0 -std=c99 -o mlock-test mlock-test.c && ./mlock-test
// CentOS 6.6                            : - mlock_status -99039
// CentOS 6.6                            : - elapsed_without_mlock 0.003735 seconds
// CentOS 6.6                            : - elapsed_with____mlock 11.424610 seconds (3058.9 times slower), average per mlock() 0.000114 seconds

// Testing OS on EC2 c3.8xlarge instance via "AWS Marketplace" Launch:

// "CentOS 6 (x86_64) - with Updates HVM": # sudo yum install glibc gcc
// "CentOS 6 (x86_64) - with Updates HVM": # gcc -O0 -std=c99 -o mlock-test mlock-test.c && ./mlock-test
// "CentOS 6 (x86_64) - with Updates HVM": - mlock_status 0
// "CentOS 6 (x86_64) - with Updates HVM": - elapsed_without_mlock 0.004739 seconds
// "CentOS 6 (x86_64) - with Updates HVM": - elapsed_with____mlock 73.994046 seconds (15614.5 times slower), average per mlock() 0.000740 seconds
// "CentOS 6 (x86_64) - with Updates HVM": [root@ip-10-130-32-44 ~]# gcc -O0 -std=c99 -o mlock-test mlock-test.c && ./mlock-test

// "CentOS 7 (x86_64) with Updates HVM"  : $ sudo yum install glibc gcc
// "CentOS 7 (x86_64) with Updates HVM"  : $ gcc -O0 -std=c99 -o mlock-test mlock-test.c && ./mlock-test
// "CentOS 7 (x86_64) with Updates HVM"  : - mlock_status -99039
// "CentOS 7 (x86_64) with Updates HVM"  : - elapsed_without_mlock 0.003984 seconds
// "CentOS 7 (x86_64) with Updates HVM"  : - elapsed_with____mlock 15.466390 seconds (3882.2 times slower), average per mlock() 0.000155 seconds

// Testing OS on EC2 c3.8xlarge instance via "Quick Start" Launch:

// ami-1ecae776: Amazon Linux 2015.03    : $ sudo yum install glibc gcc
// ami-1ecae776: Amazon Linux 2015.03    : $ gcc -O0 -std=c99 -o mlock-test mlock-test.c && ./mlock-test
// ami-1ecae776: Amazon Linux 2015.03    : - mlock_status -99039
// ami-1ecae776: Amazon Linux 2015.03    : - elapsed_without_mlock 0.003959 seconds
// ami-1ecae776: Amazon Linux 2015.03    : - elapsed_with____mlock 0.120816 seconds (30.5 times slower), average per mlock() 0.000001 seconds

// ami-d05e75b8: Ubuntu 14.04            : $ sudo apt-get update
// ami-d05e75b8: Ubuntu 14.04            : $ sudo apt-get install build-essential
// ami-d05e75b8: Ubuntu 14.04            : $ gcc -O0 -std=c99 -o mlock-test mlock-test.c && ./mlock-test
// ami-d05e75b8: Ubuntu 14.04            : - mlock_status -99039
// ami-d05e75b8: Ubuntu 14.04            : - elapsed_without_mlock 0.004230 seconds
// ami-d05e75b8: Ubuntu 14.04            : - elapsed_with____mlock 0.049550 seconds (11.7 times slower), average per mlock() 0.000000 seconds

// ami-12663b7a: RedHat 7.1              : $ sudo yum install glibc gcc
// ami-12663b7a: RedHat 7.1              : $ gcc -O0 -std=c99 -o mlock-test mlock-test.c && ./mlock-test
// ami-12663b7a: RedHat 7.1              : - mlock_status -99039
// ami-12663b7a: RedHat 7.1              : - elapsed_without_mlock 0.003817 seconds
// ami-12663b7a: RedHat 7.1              : - elapsed_with____mlock 0.079827 seconds (20.9 times slower), average per mlock() 0.000001 seconds

static double
get_time_in_seconds(void)
{
    struct timeval tv;
    gettimeofday(&tv, NULL);
    return (double)tv.tv_sec + 1.e-6 * (double)tv.tv_usec;
}

int
main()
{
    double elapsed_without_mlock;
    double elapsed_with____mlock;
    size_t len = 42;
    int    iterations = 100000;
    int    mlock_status = 0;
    {
        double start_time = get_time_in_seconds();
        for (int i = 0; i < iterations; i++) {
            char * p = malloc(len);
            mlock_status += mlock(p, len);
        }
        double end_time = get_time_in_seconds(); 
        elapsed_with____mlock = end_time - start_time;
    }
    {
        double start_time = get_time_in_seconds();
        for (int i = 0; i < iterations; i++) {
            char * p = malloc(len);
        }
        double end_time = get_time_in_seconds(); 
        elapsed_without_mlock = end_time - start_time;
    }
    printf("- mlock_status %d\n", mlock_status);
    printf("- elapsed_without_mlock %f seconds\n", elapsed_without_mlock);
    printf("- elapsed_with____mlock %f seconds (%.1f times slower), average per mlock() %f seconds\n", elapsed_with____mlock, elapsed_with____mlock / elapsed_without_mlock, (elapsed_with____mlock - elapsed_without_mlock) / iterations);
}