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SubjectRe: Linux 2.2.19pre2
On Thu, 21 Dec 2000, Andrea Arcangeli wrote:

> > The key question is: which of the following do we want?
> >
> > a) A simple, specific accept()-accelerator, and 2.2 remains without
> > an exclusive wq API or
>
> To make the accellerator we need a minimal wake-one support. So a) doesn't
> make sense to me.
>
> > b) A general purpose exclusive wq mechanism which does not correctly
> > support waiting on two queues simultaneuously where one is
> > exclusive or
>
> That's what we had in whole 2.3.x and that is better suitable for 2.2.x
> as it allows to do a) with obviously right approch and minimal effort.
>
> > c) A general purpose exclusive wq mechanism which _does_ support it.
> >
> > Each choice has merit! You seem to want b). davem wants c).
>
> I have not read any email from DaveM who proposes C for
> 2.2.19pre3 (or 2.2.x in general). Are you sure he wasn't talking
> about 2.4.x?

c) will also implement a) in an obviously right and simple way.

I've still not seen ANY reason why we'd want 2.2 to have different
wake-one semantics from 2.4...

> > And given that 2.2 has maybe 2-4 years life left in it, I'd
>
> I hope no ;).

People are still converting their 2.0 systems to 2.2 as
we speak. I really doubt that 2.2 has _less_ than 3 years
of life left ... as much as I hate this idea ;)

> > agree with David. Let's do it once and do it right while the issue
> > is fresh in our minds.
>
> I disagree. The changes to separate the two waitqueues even only
> for accept are not suitable for 2.2.x. Alan filter should forbid
> that changes. They're simply not worthwhile because I cannot
> even think at ...

They're not worthwhile just because you can't think of an example ?

The same could be said of `b)' above. Do you have an example where
that is the preferable semantics ?

If both are equally preferable (ie. nobody can think of any example
where the corner case is being used), why do you keep insisting on
giving 2.2 different wake-one semantics from 2.4 ?

[these wake-one semantics may become rather important for people
backporting drivers to 2.2 over the next years ... or to something
else which nobody has even thought about ... 2-4 years is a long
time, so 2.2 maintainability is still an issue]

regards,

Rik
--
Hollywood goes for world dumbination,
Trailer at 11.

http://www.surriel.com/
http://www.conectiva.com/ http://distro.conectiva.com.br/

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