Comment # 2 on bug 1199970 from Jan Kara

And marvin7 reaim-io-disk-ext4 regression:

                            good-27b38686           bad-077d0c2c
Hmean     disk-1       3456.22 (   4.15%)     3267.97 (  -1.53%)
Hmean     disk-25    219298.25 (  -1.17%)   198938.99 * -10.34%*
Hmean     disk-49    436201.78 (  -0.30%)   378865.98 * -13.40%*
Hmean     disk-73    600000.00 (   0.82%)   504608.30 * -15.21%*
Hmean     disk-97    734848.49 *  -4.29%*   621794.87 * -19.02%*
Hmean     disk-121   828767.12 (  -0.46%)   666055.05 * -20.00%*
Hmean     disk-145   877016.13 (  -2.82%)   744863.01 * -17.47%*
Hmean     disk-169   944134.08 (  -0.00%)   803486.53 * -14.90%*
Hmean     disk-193   900466.56 *  -4.82%*   851470.59 * -10.00%*