[Users] Enabling CUDA/OpenCL thorns by default in Simfactory?

[Roland Haas]

Hello all,

> I see the enabling/disabling of thorns like CUDA and MPI as part of
> the configuration process, just like deciding what compiler flags to
> use. On most machines you will fight hard to get the configuration
> right without Simfactory, and it's not much different than that.
Modifying the thornlist has a bit of a different flavor to it since (as
Steve pointed out) there is no outward sign ("@", special comment or
anything) that simfactory will modify the file. The file also does not
look like an obvious template and could be (and must since there are
many users out there that do not use the simfactory executable, only the
simfactory option lists) used without simfactory. This is similar to
simfactories current (it still does that, yes?) behaviour of scanning a
parfile for TerminationTrigger::max_walltime (which I *also* find
questionable but was apparently put in on explicit user request).

If we do not want to turn them on by default (we *do* turn off some
thorns we know won't compile but turning something *on* may be different
since the configuration is just fine even without the thorns)
then users have the option of adding an "enabled-thorns" line to the
bluewaters section of their defs.local.ini file. This avoids having to
modify any file that is the ET svn and (for bluewaters) users have to
provide such a section anyway to specify their allocation.

If we enable the thorns by default (this would be a the first time we do
so, yes? At least outside of machines like nvidia or the PI computeN
machines which are semi-private anyway) then we should check that
compiling them is not unusually slow (though almost anything will
compile faster than GRHydro these days) and does not pull in strange
dependencies.

So far (to me) the ET supplied thornlist had more of a character of a
master thorn list that compiles as much of the toolkit as is practical
(eg not Petsc since it is hard to get to work or Boost since it is
huge). So in light of this I would think that the proposed solution of
commenting out the OpenCL/CUDA etc thorns with a distinct comment like
!DISABLED or !REQUIRES-CUDA (and then have simfactory modify only lines
that start with !DISABLED or !REQUIRES.*) would seem like a decent
compromise between having thorn lists that can be used without
simfactory, having most of the information present at one spot (rather
than in the thornlist, the machine.ini file, defs.local.ini, the
simfactory sources) and allowing the use of a master thorn list in the
repository.

Yours,
Roland

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