Re: [PATCH v4 16/19] IB/mad: Add Intel Omni-Path Architecture defines

["ira.weiny" <ira.weiny-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>]

On Fri, Apr 03, 2015 at 05:33:55PM -0600, Hefty, Sean wrote:
> >  /* Registration table sizes */
> >  #define MAX_MGMT_CLASS		80
> > -#define MAX_MGMT_VERSION	8
> > +#define MAX_MGMT_VERSION	0x83
> 
> It's unfortunate that this results in a big jump in used versions.  Mad_priv.h defines this:

It is unfortunate.

> 
> struct ib_mad_port_private {
> 	...
> 	struct ib_mad_mgmt_version_table version[MAX_MGMT_VERSION];
> 
> struct ib_mad_mgmt_version_table {
> 	struct ib_mad_mgmt_class_table *class;
> 	struct ib_mad_mgmt_vendor_class_table *vendor;
> };
> 
> This ends up allocating about 2K of data per port of NULL pointers.  Not a huge deal, but still.

I agree this is not ideal but this is not a large amount of space.  Nor is this
something which is dynamically being allocated.

> 
> I don't have a great fix here.  Maybe the version[] array can be the necessary size, with some sort of simple mapping function from version to the index?

I did not have a great fix either.  Hence the current implementation.

Frankly I don't know of many systems that have more than a few ports and at 2K
each this does not seem like a big deal.

Ira

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