results_buffered_ra256
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[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: 256 4kb blocks read: Success real 0m9.786s user 0m0.034s sys 0m1.840s 8kb blocks read: Success real 0m9.868s user 0m0.020s sys 0m1.698s 16kb blocks read: Success real 0m9.836s user 0m0.009s sys 0m1.591s 32kb blocks read: Success real 0m10.078s user 0m0.007s sys 0m1.691s 64kb blocks read: Success real 0m9.819s user 0m0.008s sys 0m1.688s 128kb blocks read: Success real 0m9.876s user 0m0.002s sys 0m1.685s 256kb blocks read: Success real 0m9.811s user 0m0.001s sys 0m1.643s 512kb blocks read: Success real 0m9.861s user 0m0.001s sys 0m1.671s 1024kb blocks read: Success real 0m9.811s user 0m0.002s sys 0m1.728s 2048kb blocks read: Success real 0m9.985s user 0m0.001s sys 0m1.820s 4096kb blocks read: Success real 0m9.845s user 0m0.002s sys 0m1.832s 8192kb blocks read: Success real 0m9.789s user 0m0.000s sys 0m1.921s