write.c

UNIX下编程同步与异步write的效率比较。包含apue.h、error2e.c、write.c

#include "apue.h"
#include <unistd.h>
#include <fcntl.h>
#include <sys/times.h>



#define FILENAMESIZE 80
#define SIZE 1024
#define TESTTIMES 8




int main( int argc, char *argv[] )
{ 
	struct tms begin, end;
	clock_t Begin, End;
	char outfilename[FILENAMESIZE],
		* buffer;
	long filesize, loops, buffersize, n;
	pid_t outfile;
	double sys_click, stime, utime, total;
	
	if( argc == 2 )
	{
		strcpy( outfilename, argv[1] );
		if( ( outfile = open( outfilename, O_WRONLY | O_CREAT | O_TRUNC, 0644 ) ) == -1 )
			err_sys( "Open outfile error!\n" );
	}
	else if( argc == 3 )
	{
		if( strcmp( argv[2], "sync" ) != 0 )
			err_sys( "Arguments error!\n" );
		else
		{ 
			strcpy( outfilename, argv[1] );
			if( ( outfile = open( outfilename, O_WRONLY | O_CREAT | O_TRUNC | O_SYNC, 0644 ) ) == -1 )
				err_sys( "Open outfile error!\n" );
		}
	}
	else
		err_sys( "Argument error!\n" );
		
	if( ( filesize = lseek( STDIN_FILENO, 0, SEEK_END ) ) == -1 )
		err_sys( "SEEK_END file error!\n" );
	if( ( buffer = (char *)malloc( filesize * sizeof(char) + 1 ) ) == NULL )
		err_sys( "Malloc error!\n" );
	if( lseek( STDIN_FILENO, 0, SEEK_SET ) == -1 )
		err_sys( "SEEK_SET file error!\n" );
	if( read( STDIN_FILENO, buffer, filesize ) != filesize )
		err_sys( "Read file error!\n" );
	buffer[filesize] = '\0' ;
	
	sys_click = sysconf( _SC_CLK_TCK );
	printf("  BUFFERSIZE   \tUsercpu_time(s)\t Syscpu_time(s)\t  Clock_time(s)\t  Loop_times   \n");
	for( buffersize = SIZE, n = 0; n < TESTTIMES; buffersize *= 2, n++ )
	{
		loops = 0;
		Begin = times( &begin );
		lseek( outfile, 0, SEEK_SET );
		while( loops * buffersize < filesize )
		{
			if( write( outfile, buffer + loops * buffersize, buffersize ) == -1 )
				err_sys( "Write error!\n" );
			loops++;
		}
		End = times( &end );
		utime = (double)( end.tms_utime - begin.tms_utime ) / sys_click;
		stime = (double)( end.tms_stime - begin.tms_stime ) / sys_click;
		total = (double)( End - Begin ) / sys_click;
		printf( " %11d\t %4.6f\t %4.6f\t  %4.6f\t%10d\n", buffersize, utime, stime, total, loops );
	}

	free( buffer );
	
	return 0;
}