$ time (dd if=/dev/zero of=zerofile bs=1M count=500;sync);rm zerofile
Feb. 1, 2012, 5:35 p.m. — DAVEB
Creates a 500MB blank file and times how long it takes to finish writing the entire thing to disk (sync)
time the entire dd + sync operation, and then remove the temporary file
time
dd + sync
Works with Bash; not tested in other environments