do_loops.c

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/* Compile me with -O0 or else you'll get none. */
 
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <assert.h>
#include <fcntl.h>
#include <sys/time.h>
 
#include "do_loops.h"
 
volatile int buf[CACHE_FLUSH_BUFFER_SIZE_INTS];
volatile int buf_dummy = 0;
volatile int *flush = NULL;
volatile int flush_dummy = 0;
volatile double a = 0.5, b = 2.2;
 
void
do_reads( int n )
{
    int i, retval;
    static int fd = -1;
    char buf;
 
    if ( fd == -1 ) {
        fd = open( "/dev/zero", O_RDONLY );
        if ( fd == -1 ) {
            perror( "open(/dev/zero)" );
            exit( 1 );
        }
    }
 
    for ( i = 0; i < n; i++ ) {
        retval = ( int ) read( fd, &buf, sizeof ( buf ) );
        if ( retval != sizeof ( buf ) ) {
            if ( retval < 0 )
                perror( "/dev/zero cannot be read" );
            else
                fprintf( stderr,
                         "/dev/zero cannot be read: only got %d bytes.\n",
                         retval );
            exit( 1 );
        }
    }
}
 
void
fdo_reads( int *n )
{
    do_reads( *n );
}
 
void
fdo_reads_( int *n )
{
    do_reads( *n );
}
 
void
fdo_reads__( int *n )
{
    do_reads( *n );
}
 
void
FDO_READS( int *n )
{
    do_reads( *n );
}
 
void
_FDO_READS( int *n )
{
    do_reads( *n );
}
 
void
do_flops( int n )
{
    int i;
    double c = 0.11;
 
    for ( i = 0; i < n; i++ ) {
        c += a * b;
    }
    dummy( ( void * ) &c );
}
 
void
fdo_flops( int *n )
{
    do_flops( *n );
}
 
void
fdo_flops_( int *n )
{
    do_flops( *n );
}
 
void
fdo_flops__( int *n )
{
    do_flops( *n );
}
 
void
FDO_FLOPS( int *n )
{
    do_flops( *n );
}
 
void
_FDO_FLOPS( int *n )
{
    do_flops( *n );
}
 
void
do_misses( int n, int bytes )
{
    register int i, j, tmp = buf_dummy, len = bytes / ( int ) sizeof ( int );
    dummy( ( void * ) buf );
    dummy( ( void * ) &buf_dummy );
    assert( len <= CACHE_FLUSH_BUFFER_SIZE_INTS );
    for ( j = 0; j < n; j++ ) {
        for ( i = 0; i < len; i++ ) {
            /* We need to read, modify, write here to look
               out for the write allocate policies. */
            buf[i] += tmp;
            /* Fake out some naive prefetchers */
            buf[len - 1 - i] -= tmp;
        }
        tmp += len;
    }
    buf_dummy = tmp;
    dummy( ( void * ) buf );
    dummy( ( void * ) &buf_dummy );
}
 
void
fdo_misses( int *n, int *size )
{
    do_misses( *n, *size );
}
 
void
fdo_misses_( int *n, int *size )
{
    do_misses( *n, *size );
}
 
void
fdo_misses__( int *n, int *size )
{
    do_misses( *n, *size );
}
 
void
FDO_MISSES( int *n, int *size )
{
    do_misses( *n, *size );
}
 
void
_FDO_MISSES( int *n, int *size )
{
    do_misses( *n, *size );
}
 
void
do_flush( void )
{
    register int i;
    if ( flush == NULL )
        flush = ( int * ) malloc( ( 1024 * 1024 * 16 ) * sizeof ( int ) );
    if ( !flush )
        return;
 
    dummy( ( void * ) flush );
    for ( i = 0; i < ( 1024 * 1024 * 16 ); i++ ) {
        flush[i] += flush_dummy;
    }
    flush_dummy++;
    dummy( ( void * ) flush );
    dummy( ( void * ) &flush_dummy );
}
 
void
fdo_flush( void )
{
    do_flush(  );
}
 
void
fdo_flush_( void )
{
    do_flush(  );
}
 
void
fdo_flush__( void )
{
    do_flush(  );
}
 
void
FDO_FLUSH( void )
{
    do_flush(  );
}
 
void
_FDO_FLUSH( void )
{
    do_flush(  );
}
 
void
do_l1misses( int n )
{
    do_misses( n, L1_MISS_BUFFER_SIZE_INTS );
}
 
void
fdo_l1misses( int *n )
{
    do_l1misses( *n );
}
 
void
fdo_l1misses_( int *n )
{
    do_l1misses( *n );
}
 
void
fdo_l1misses__( int *n )
{
    do_l1misses( *n );
}
 
void
FDO_L1MISSES( int *n )
{
    do_l1misses( *n );
}
 
void
_FDO_L1MISSES( int *n )
{
    do_l1misses( *n );
}
 
void
do_stuff( void )
{
    static int loops = 0;
 
    if ( loops == 0 ) {
        struct timeval now, then;
        gettimeofday( &then, NULL );
        do {
            do_flops( NUM_FLOPS );
            do_reads( NUM_READS );
            do_misses( 1, 1024 * 1024 );
            gettimeofday( &now, NULL );
            loops++;
        } while ( now.tv_sec - then.tv_sec < NUM_WORK_SECONDS );
    } else {
        int i = 0;
        do {
            do_flops( NUM_FLOPS );
            do_reads( NUM_READS );
            do_misses( 1, 1024 * 1024 );
            i++;
        } while ( i < loops );
    }
}
 
void
do_stuff_( void )
{
    do_stuff(  );
}
 
void
do_stuff__( void )
{
    do_stuff(  );
}
 
void
DO_STUFF( void )
{
    do_stuff(  );
}
 
void
_DO_STUFF( void )
{
    do_stuff(  );
}
 
void
dummy( void *array )
{
/* Confuse the compiler so as not to optimize
   away the flops in the calling routine    */
/* Cast the array as a void to eliminate unused argument warning */
    ( void ) array;
}
 
void
dummy_( void *array )
{
    ( void ) array;
}
 
void
dummy__( void *array )
{
    ( void ) array;
}
 
void
DUMMY( void *array )
{
    ( void ) array;
}
 
void
_DUMMY( void *array )
{
    ( void ) array;
}
 
/* We have to actually touch the memory to confuse some
 * systems, so they actually allocate the memory.
 * -KSL
 */
void
touch_dummy( double *array, int size )
{
    int i;
    double *tmp = array;
    for ( i = 0; i < size; i++, tmp++ )
        *tmp = ( double ) rand(  );
}