Re: Disk scheduling policy (Re: NEW_BUFQ_STRATEGY)

On Dec 1, 2003, at 4:23 PM, Thor Lancelot Simon wrote:

> Well, I have yet to encounter one that randomly shuffles blocks
> such that sorting in order of increasing block number would be
> _harmful_.  Indeed, since we can see more information about future
> requests than the disk can, it's not clear to me why the elevator
> sort is not highly beneficial.

Well, I certainly agree that elevator sort is not really *harmful*, so 
long as doing it doesn't defeat any queueing tricks that the disk is 
trying to do.  (This all gets really spooky when your "disk" is really 
a disk array with some huge chunk of cache memory in front of it.)

         -- Jason R. Thorpe <[email protected]>