The transparent huge page shrinker

My application supports many different operating systems, not only Linux. I try to keep my code base portable, I am willing to add workarounds for specific operating systems to my application if it will provide a significant benefit to my users and the workaround is relatively small. However, in this case I don't think is worth the effort. In my opinion the current Linux support of transparent huge pages is a mess (to be fair, on Windows it is even worse) and I prefer to simply wait until the situation improves and hopefully transparent huge pages will eventually be enabled by default.

#include <stdlib.h>
#include <unistd.h>
#include <sys/mman.h> // Also used for various posix functions, cross platform
const int alignment = 1 << 21;
const int size = 16 << 21;
int main( void ) {
    void *x = aligned_alloc( alignment, size );

#ifdef MADV_HUGEPAGE
    if ( x != NULL ) {
        madvise( x, size, MADV_HUGEPAGE  );
    }
#endif

    printf( "Go run: grep -i hugepage /proc/meminfo\nPausing for 60 seconds.\n" );
    sleep( 60 );

    return 0;
}

    system("echo \"requested 32MB of anon huge pages:\";\
            grep -i hugepage /proc/meminfo");
    //printf( "Go run: grep -i hugepage /proc/meminfo\nPausing for 60 seconds.\n" );
    //sleep( 60 );

requested 32MB of anon huge pages:
AnonHugePages:      6144 kB
ShmemHugePages:        0 kB
FileHugePages:         0 kB
HugePages_Total:       0
HugePages_Free:        0
HugePages_Rsvd:        0
HugePages_Surp:        0
Hugepagesize:       2048 kB

#ifdef MADV_HUGEPAGE
    if ( x != NULL ) {
        madvise( x, size, MADV_HUGEPAGE )
        for ( int i = 0; i < size; i += alignment ) {
            ((char *)x)[i] = 0;
        }
    }
#endif