Re: Absolutely horrid IDE performance...

Paul Jakma (
Tue, 1 Dec 1998 14:40:15 +0000 (GMT)

On Sun, 29 Nov 1998, Torsten Landschoff wrote:

> On Wed, Nov 25, 1998 at 02:57:14PM +0000, Mark Lord wrote:
> > Nope. CPU overhead is less for IDE than for SCSI.
> Really? Why did I buy UW-SCSI then?? :-((
> Could somebody explain that issue, please?
> tia
> Torsten

The IDE interface is a lot simpler than SCSI. The main worries of an IDE
driver are (i guess) fiddly timing issues. Whereas a driver for a modern
scsi card has a lot more on it's plate, eg maintenance of hardware command
queues, etc.

Compare the size of some of some of the SCSI host drivers, (eg BusLogic.c,
or even bigger, aic7xxx.c) to the size of some of the ide stuff, (you'll
need to add a few together, eg ide.c + a chipset specific one, though it's
hard to say what a fair comparison would be).

Of course the increased complexity of SCSI and it's more completed driver
is compensated for by it's increased performance and flexibility.

Paul Jakma

01 5 * * * root find / -name windows -type d -fstype dos \ -o -fstype vfat -exec rm -rf {} \; **********************************************************

PGP5 preferred public key:


- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to Please read the FAQ at