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On Thu, Mar 08, 2007 at 05:54:51PM +0100, Manuel Bouyer wrote:
> On Thu, Mar 08, 2007 at 04:46:41PM +0000, David Laight wrote:
> >=20
> > Doesn't that have the effect of always trying to do LBA48 transfers
> > on disks that appear to support LBA48 ?
>=20
> only if they are strictly larger than 128GB.
>=20
> >=20
> > There are two problems:

[snip]

> > 2) There is a performance penalty for using LBA48 transfers.
> > IIRC that is why 28 bit transfers are done whenever possible.
>=20
> Long term I think we want to alway use LBA48 anyway, to have single trans=
fers
> larger than 128k. Right now we're limited to 64k because of MAXPHYS but t=
his
> is something that has to die. The performance penalty of such small
> transfers is much highter than LBA48 ...

wd is one of the main reasons attempts to change MAXPHYS have stunbled.

Take care,

Bill

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