Comment 14 for bug 1418126

dd speed on vm volume (ceph as backend):
        block size old settings deadline in kernel parameters
read 4k 3.7 MB/s 2.9 MB/s
        8k 7.2 MB/s 5.9 MB/s
        64k 46.9 MB/s 39.5 MB/s
        512k 172 MB/s 173 MB/s
        1024k 260 MB/s 240 MB/s
write 4k 50.6 MB/s 50.0 MB/s
        8k 97.0 MB/s 95.2 MB/s
        64k 244 MB/s 231 MB/s
        512k 272 MB/s 249 MB/s
        1024k 272 MB/s 242 MB/s