Subject: Re: [openib-general] [PATCH 5/5] [RFC] Infiniband: connection abstraction

From: Grant Grundler <[email-masked]>
Date: Wed, 18 Jan 2006 10:49:45 -0800

On Wed, Jan 18, 2006 at 10:19:01AM -0800, Sean Hefty wrote:
> Roland Dreier wrote:
> > > +	UCMA_MAX_BACKLOG	= 128
> >
> >Is there any reason that we might want to make this a tunable?  Maybe
> >as a module parameter that's writable in sysfs...
> 
> There's no reason not to make this tunable.

Yes, there are reasons to NOT make something a tunable:
o increases system complexity (admin)
o increases the amount of documentation (learning curve)
o increases test matrix/cost (devel/support cost)
o generally hurts performance (var vs a constant of the same value)

Any reason to make something a tunable has to compensate
for the above drawbacks. An answer to Roland's question
is a reasonable prerequisite if someone wants add a tunable.

IB doesn't have the much in /sys/class/infiniband* or module parameters
and I think that's a Good Thing.

grant