[openib-general] [PATCH][RFC] kDAPL: remove dat wrapper funct ion dat_ia_query()

[James Lentini]

There is precedent for including a pointer to the function pointer 
table in each top level object. The OpenIB stack does this; each IB 
object (ib_pd, ib_qp, ib_mr, etc.) contain a pointer to the ib_device 
structure. Of course I know that just because it was done before 
doesn't make it right.

james

On Mon, 13 Jun 2005, James Lentini wrote:

>
>
> On Sun, 12 Jun 2005, Tom Duffy wrote:
>
>> On Sat, 2005-06-11 at 11:20 +0200, Christoph Hellwig wrote:
>>> Currently every dapl object embedds dapl_common which has a pointer
>>> to the dapl_ia.  Now fixing that mess up a little every dat object
>>> can have a dat_ia pointer (without the utter _common braindamage)
>>> and there's one additional dereference, while saving one pointer per
>>> allocated object.
>> 
>> The compiler should be smart enough to not make the access any more
>> costly since they contain that struct and don't have a pointer to it,
>
> I believe the "one additional dereference" Christoph was referring to occurs 
> if we implement his proposal and define dat objects as follows:
>
> struct dat_ia {
> 	struct dat_provider *provider;
> 	union dat_context context;
> }
>
> struct dat_foo {
> 	struct dat_ia *ia;
> 	union dat_context context;
> }
>
>> but I do agree that the _common structure is not ideal and sorta ugly.
>
> I like it on the basis that if gathers up the common structure members in one 
> place, hence making maintenance of these fields easier in the future. 
> Granted, there are only two of them, so losing it wouldn't be a big deal.
>
>> 
>> -tduffy
>> 
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