Re: elevator algorithm bug in ll_rw_blk.c

Gerard Roudier (groudier@club-internet.fr)
Mon, 16 Nov 1998 21:04:01 +0100 (MET)


On Sun, 15 Nov 1998, Vojtech Pavlik wrote:

> On Sun, Nov 15, 1998 at 07:24:46PM +0000, Riley Williams wrote:

> You could apply a two way elevator well if you knew about the physical
> characteristics of the drive. Unfortunately there is no way to find that out
> for most modern drives.

Just consider the following:

1 - File are mostly allocated in ascending block order.
2 - Applications most of the time read file sequentially and the
kernel does read-ahead.
3 - Hard disks prefetch data ahead.

Who still want to ever walk the drive in the reverse direction?
No need to be intelligent when being cleverly stupid works great? ;-)

Regards,
Gerard.

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