mrburns:~ liberie$ time dd if=/dev/zero of=img.tst bs=2048 count=1m
1048576+0 records in
1048576+0 records out
2147483648 bytes transferred in 24.689114 secs (86980993 bytes/sec)

real	0m24.811s
user	0m0.290s
sys	0m5.931s