Bogdan.Costescu at iwr.uni-heidelberg.de
Thu Sep 29 08:34:28 EDT 2005
On Wed, 28 Sep 2005, Greg M. Kurtzer wrote:
>> But your MPI implementation likely requires the X libraries, and
>> perhaps a few interpreters
> Can you elaborate on why an MPI implementation would require Xlibs?
I can't read Donald's mind - I suppose that he refers not to the
communication libraries, but the associated tools, like profiling or
debugging ones... which points to a packaging problem: why associate
the 2 when the purpose is clearly different (runtime vs. development) ?
But this raises another packaging vs. usage question: how much
fine-grained can the packages be made ? Let's consider the 2 extremes:
1. Put everything in one package.
easy to install (rpm -i M.rpm or yum install M)
everything is installed (so no users complaining of missing parts)
large(r) package size (bad for ramdisks, speed of transfer)
2. Put any files that have any chance of being used for a different
purpose or in a different way in a different package, like libraries
in one package, startup/runtime binaries in another, CLI tools in yet
another, X tools in another, Java (and implicitly X) tools in another,
etc. and spend time finding proper dependencies for each package.
small individual package size
difficult to install in the right order (yum helps here)
packages might be missed
The last 2 are actually those that IMHO make a negative impression.
The fact that automatic dependency resolution can be done
automatically is not the whole story, even in the (ideal) situation
where all software (including end-user applications) is packaged.
There is still the issue of how users want to use the various parts of
the software, which are now in different packages and might not be
installed by the admin, because they were not deemed important enough
or because the dependency chain did not bring them in automatically:
for example, running a MPI application requires only the runtime parts
of the MPI distribution, which means that development parts,
documentation, etc. might not be installed. And at this point the
admin wants to be on the safe side or is confused by the multitude of
packages and installs most (all) packages anyway - and then where's
the advantage over the single package that provides everything ?
An intermediate solution is to add some meta-packages that have no
content, but only dependencies from the fine-grained packages. This
helps a bit those admins that know in principle what is needed, but a
meta-package might still bring in too many dependencies and confuses
even more a clueless admin. [same applies to yum groups]
> No need to replicate technologies that already exist for this purpose.
IMHO, it's even worse to use existing technologies in an improper or
inefficient way: because you can, you don't necessarily have to. Just
as an example, I'll take one of your commands:
> # yum --installroot /vnfs/default install/remove moooo
If you want to install a number crunching application that doesn't
need any fancy libs, it's much faster to use 'rpm -i' than 'yum
install'. IMHO running 'yum update' nightly on compute nodes is a
waste, especially when you make the effort of getting all kinds of
optimized libraries and optimizing compilers to speed up the
application that runs on the very same nodes.
IWR - Interdisziplinaeres Zentrum fuer Wissenschaftliches Rechnen
Universitaet Heidelberg, INF 368, D-69120 Heidelberg, GERMANY
Telephone: +49 6221 54 8869, Telefax: +49 6221 54 8868
E-mail: Bogdan.Costescu at IWR.Uni-Heidelberg.De
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