System administration command. Set the latency in the elevator algorithm used to schedule I/O activities for the specified block devices. If no options are given, print the current settings for devices.
Set the maximum coalescing factor allowed on writes when reads are pending to N.
Print help message, then exit.
Set the maximum read latency (basically, the number of sectors to read before writes are allowed) to N. The default is 8192.
Print version number, then exit.
Set the maximum write latency (sectors to write before allowing a read) to N. The default is 16384.