set logscale y
set logscale x
set xlabel "Block Size in Bytes"
set ylabel "Time to Write 2 Mbyte"
set terminal postscript color
set output "myfile.ps"
set title "Time to Write a 2 Mbyte File Using Different Block Sizes\nTime in System Ticks "
plot "plot_data" using 1:2 title 'O_Sync' with linespoints, \
"plot_data" using 1:3 t 'Without O_Sync' w linespoints