Re: elevator code in kernel

Jens Axboe (axboe@suse.de)
Sat, 29 Apr 2000 01:48:15 +0200

On Fri, Apr 28 2000, Kip Matthew Macy wrote:
> Is it necessary for the elevator sorting code to be hard-coded into the
> kernel?
>
> Elevator sorting offers little or no benefit to higher performance I./O
> devices - An
> extreme example would be RAID controllers that have on card memory that
> can do
> reordering more intelligently themselves. A more general example would
> be a typical
> IDE drive with a 2MB buffer that automatically reorders writes to
> minimize head
> movement.

You raise some good points, and I am making the elevator code more
modular as we speak. That will give different drivers the opportunity
to select the elevator (or not select) the one they want. But elevator
reordering is really not that expensive and can work on much larger
sets of data then the typical drive.

-- 
*  Jens Axboe <axboe@suse.de>
*  Linux CD/DVD-ROM, SuSE Labs
*  http://kernel.dk


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