I think that processing things inside comments is confusing (if that's
what's happening), unless there's some special tag in the comment, e.g.
@@. Wouldn't it make more sense for SimFactory to accept the list of
uncommented thorns, and disable if appropriate?
Cheers,
Steve
On 05/27/2014 12:01 PM, Ian Hinder wrote:
On 27 May 2014, at 17:23, Erik Schnetter <[email protected]
<mailto:[email protected]>> wrote:
On Tue, May 27, 2014 at 10:51 AM, Frank Loeffler <[email protected]
<mailto:[email protected]>> wrote:
On Tue, May 27, 2014 at 09:46:29AM -0500, Frank Loeffler wrote:
> Wouldn't that mean that every checkout on such a machine fails,
because
> simfactory would unconditionally add these thorns to the thornlist,
> regardless of whether they are actually present or not?
Replying to myself: Is this really what Simfactory does - or does it
only "enable" these thorns when they are present in the
thornlist, but
commented out? If the latter is the case I think it should be fine,
although it might still confuse people that don't even look at the
simfactory configuration of the machine, and use a thornlist with
such a
thorn commented out, but not present. Could we somehow let these
users
give a hint why Cactus fails with 'thorn not found', when the
original
thornlist clearly commented it out?
As per our previous discussion, the standard ET thorn list will (and
this is the current state)
1. Check out all CUDA and OpenCL thorns, on ALL machines
2. Disable all CUDA and OpenCL thorns when building Cactus, on ALL
machines
If you are using this standard thorn list directly, then this is the
only reasonable way to go; other choices don't make sense.
Simfactory pre-processes thorn lists, in the same way it
pre-processes option lists and parameter files, expanding variables.
It is important to have such a pre-processing step, since it avoids
having to do this manually. This is how Simfactory "fixes" things for
various machines, it is an important part of how it works.
Blue Waters supports both CUDA and OpenCL. We now have two options:
1. Use the standard ET thorn list there, i.e. disabling CUDA and
OpenCL by default
2. Automatically enable CUDA and OpenCL thorns
As others mentioned, it does not make sense to enable CUDA and OpenCL
everywhere, since it would not be supported everywhere. Enabling the
thorns but adding a mechanism that turns these thorns into dummy
thorns that do nothing also doesn't make sense -- think of a BSSN
thorn written in CUDA; turning it into a dummy thorn that does
nothing on a non-CUDA machine would just mean that BSSN evolution
doesn't happen there. There are machines that support CUDA and there
are machines that don't, and if you want to use CUDA then you will
need to get an error message when you try to use a machine that
doesn't support CUDA.
So -- how do we want to support CUDA on Blue Waters?
1. Ask people to manually change the thorn list, in effect asking
them to maintain one thorn list per machine
2. Let Simfactory do this, since it already knows what works on what
machine and what doesn't
I don't think there are any other choices.
In case you are wondering: What I propose won't break checking out
thorns on any machine, and won't break the build on any machine, and
won't require people to do special things for special machines. I
regularly build on many machines, and I do so in an automated manner,
and I don't maintain per-machine thorn lists or parameter files.
Simfactory has an MDB that encodes all the machines' peculiarities,
and the information there is sufficient to use all of our machines
efficiently, and in an automated manner.
There is the argument of "this would surprise people". If we are
worried about people being surprised that a CUDA thorn can't be
activated on a non-CUDA machine, then maybe we need to raise our
expectations a bit.
I have been "surprised" in the past when I saw a thorn commented out
in the thornlist, and Cactus trying to build it because SimFactory has
enabled it on a particular machine. I had no idea what was going on,
and couldn't believe that simfactory was doing this when I found that
it was. I think if something is commented out, it should be ignored.
Maybe we could add a feature to the Cactus thornlist language for
"included if available"? e.g.
? Arrangement/Thorn
SimFactory could expand this, and Cactus would ignore it by default.
This is similar to the existing "!" comments which are used by
GetComponents, and ignored by Cactus. At least this way, it doesn't
look like it has been commented out.
--
Ian Hinder
http://numrel.aei.mpg.de/people/hinder
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