[Bug-ddrescue] ddrescue speedup

[Dave Yost]

Hi.

Another idea would be to fork off some threads to do the splitting in 
parallel.  If the disk drivers and/or drives are brilliant, the reads 
should get ordered such that you pay a minimum penalty for rotational 
latency.  The idea is that if there are two reads to be done on the 
same cylinder, then the one rotationally closest to the head will go 
first.

Dave