results_buffered_ra4096
text/plain
[craig@ayaki tmp]$ echo -n "direct=f Readahead: "; sudo blockdev --getra /dev/sda; for (( x = 2; x < 14; x++ )); do echo $((1<<x))kb blocks; echo 1 | sudo tee -a /proc/sys/vm/drop_caches >/dev/null; time ./io $((1<<x)) test_file; done direct=f Readahead: 4096 4kb blocks read: Success real 0m10.178s user 0m0.015s sys 0m1.167s 8kb blocks read: Success real 0m10.037s user 0m0.006s sys 0m1.180s 16kb blocks read: Success real 0m10.303s user 0m0.004s sys 0m1.230s 32kb blocks read: Success real 0m10.870s user 0m0.003s sys 0m1.148s 64kb blocks read: Success real 0m10.194s user 0m0.004s sys 0m1.080s 128kb blocks read: Success real 0m10.401s user 0m0.004s sys 0m1.233s 256kb blocks read: Success real 0m10.087s user 0m0.000s sys 0m1.202s 512kb blocks read: Success real 0m10.061s user 0m0.001s sys 0m1.280s 1024kb blocks read: Success real 0m10.161s user 0m0.003s sys 0m1.301s 2048kb blocks read: Success real 0m10.246s user 0m0.000s sys 0m1.291s 4096kb blocks read: Success real 0m9.996s user 0m0.002s sys 0m1.366s 8192kb blocks read: Success real 0m9.997s user 0m0.001s sys 0m1.599s