Re: [Swsusp-devel] Re: Dropping CONFIG_PM_DISK?

From: Arjan van de Ven
Date: Mon Mar 01 2004 - 09:41:59 EST


On Mon, Mar 01, 2004 at 10:33:43PM +0800, Michael Frank wrote:
> On Mon, 01 Mar 2004 14:47:23 +0100, Arjan van de Ven <arjanv@xxxxxxxxxx>
> wrote:
>
> >
> >>Then one could just drop in a driver from 2.4 and use it.
> >>
> >>People having time to make new "pretty" drivers could
> >>also use this facility for cross checking.
> >
> >I'm sorry but this is a load of bull ;)
>
> Thank you, I do fully concur with you from an ideal scientific perspective
> where resources are not constrained. Applying the same perspective I might
> like to craft lots of drivers in assembler or even reinvent whatever...,
> but I do not live an ideal world.

I do not live an ideal world, However I do live in a practical world of
having to put distribution kernels together.
>
> >New kernel revisions come with a new API. If we keep the old one around
> >forever that achieves two things
> >1) The kernel bloats up
>
> By a few %, only when old API is used, the benefits far outweighs the cost.

Ehm no. You entirely forget the cost where the new API and old API need to
work together, which is a significant complexity explosion. When linux grows
a new API that touches so many drivers, there's a good reason for that, eg
the API improves something or makes something possible.
Making powermanagement work is hard, even with 1 API to worry about. With 2
interfering API's it becomes outright impossible and untrackable.
That's not a scientific perspective, that's a practical perspective where
the scientific theory maybe says you can have 2 parallel api's that never
interact ;)

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