[RFC] callout overhaul: part I

[Attilio Rao]

2007/11/10, Poul-Henning Kamp <phk at phk.freebsd.dk>:
> 1.  About the name
> ------------------
>
> In my proposal I used a generic XXX_ prefix, because nailing the
> name was not the bikeshed I wanted to paint.
>
> You have chosen "callout" but I'm not sure I like that very much,
> this is not really a callout facility, it is a timer facility.
>
> I don't like when core APIs have silly long names, that clutters
> up source code needlessly, so my preference would probably be
> to use a short prefix, something like "tmr", "when", "wake" or
> similar.
>
> But let's take that offline and not start a bikeshed here.

Well, I have no name preference really, so if you have something
better in mind it is good.
For the moment however, as I'm concentrating in adding "missing
support" I want to remain more callout compliant.

> 2.  About XXX_instances
> -----------------------
>
> You propose a XXX_arm() and a XXX_arm_cpu().  That is a pointless
> limitation.
>
> My API proposal said specifically:
>
> > The functions above will actually be wrappers for a more generic
> > set of the same family, which also takes a pointer to a callout-group.
>
> And I guess the meaning of this was too subtle, so I will elaborate:
>
> The fundamental function will be called
>
>         XXX_arm_cg(struct xxx_group *cg, ...)
>
> The xxx_group argument can be NULL, in which case a group is
> chosen for you by unspecified means.

Is this group, in your idea, sorta of a node of the heap you
previously discussed in the thread?

> 3. Two stage conversion
> -----------------------
>
> You propose a two-stage conversion.  That is a bad idea when we
> can do it as efficiently with a one-stage conversion.
>
> Having thought a bit more about the conversion, I think the right
> way to do this is parallel implementations:  Lets add the new
> API and start converting critical code to use it.

This is good.
Speaking of which, perforce can really help in breaking commits in mealpieces.

Thanks,
Attilio


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