[craig@ayaki tmp]$ echo -n "Readahead: "; sudo blockdev --getra /dev/sda; for (( x = 2; x < 14; x++ )); do echo $((1<<x))kb blocks; time ./io $((1<<x)) test_file; done
Readahead: 256
4kb blocks
read: Success

real	0m38.252s
user	0m0.045s
sys	0m12.866s
8kb blocks
read: Success

real	0m22.145s
user	0m0.021s
sys	0m8.383s
16kb blocks
read: Success

real	0m14.221s
user	0m0.012s
sys	0m5.489s
32kb blocks
read: Success

real	0m10.835s
user	0m0.004s
sys	0m4.500s
64kb blocks
read: Success

real	0m9.752s
user	0m0.003s
sys	0m3.658s
128kb blocks
read: Success

real	0m9.980s
user	0m0.000s
sys	0m3.513s
256kb blocks
read: Success

real	0m9.872s
user	0m0.001s
sys	0m3.245s
512kb blocks
read: Success

real	0m9.814s
user	0m0.000s
sys	0m3.173s
1024kb blocks
read: Success

real	0m9.880s
user	0m0.001s
sys	0m3.170s
2048kb blocks
read: Success

real	0m11.961s
user	0m0.000s
sys	0m3.380s
4096kb blocks
read: Success

real	0m11.374s
user	0m0.002s
sys	0m3.348s
8192kb blocks
read: Success

real	0m11.970s
user	0m0.000s
sys	0m3.312s