tgamblin

9 ms·

31.
by tgamblin 3y ago
Love this article and the push to build awareness of what modern SAT solvers can do. It's worth mentioning that there are higher level abstractions that are far more accessible than SAT. If I were teaching a course on this, I would
32.
Simplifying HPC dependency solving with logic programming(arxiv.org)
3 points by tgamblin 3y ago|0 comments
33.
by tgamblin 4y ago
I work at LLNL so I work with people who make cool simulations all the time. The coolest ones I’ve seen lately were the ones that helped with last year’s big fusion ignition shot at NIF. There is a (very) recent article summarizing how simu
34.
Is there a feasible preimage attack for any hash function today?(crypto.stackexchange.com)
2 points by tgamblin 4y ago|2 comments
35.
by tgamblin 4y ago
Spack packages are parameterized, so there is one `package.py` file per package, not several, and you can have many versions and options declared. See, e.g., `zstd`: https://github.com/spack/spack/blob/deve
36.
by tgamblin 4y ago
Maybe I should clarify: > it basically boils down to removing that directory + the environment module file that EasyBuild generated for it Another important thing is knowing what depends on that package (so you don't remove somethin
37.
by tgamblin 4y ago
> So how would I know whether the prebuilt binaries were built in a longer path than I install to? All the public ones are built with very long padding; if you make your own you're currently on your own. > Is there at least a way
38.
by tgamblin 4y ago
> do prebuilt binaries rerouted to be installed in a predefined path they were built in or is it also flexible? Prebuilt binaries don't have to go in a fixed prefix -- we'll relocate RPATHs, shebangs, strings in text files, and
39.
by tgamblin 4y ago
Yep, it works with Lmod ( https://lmod.readthedocs.io ) and environment modules ( https://modules.sourceforge.net ). See the tutorial on setting up modules for what the integration looks like: * https://spack
40.
by tgamblin 4y ago
HPC isn't exactly special, and neither to some extent is Spack. Spack's gotten some attention in talks at, e.g., CppCon. The big differentiator is really the degree to which people want to tune and customize their builds in HPC v
41.
by tgamblin 4y ago
Yep! I'm not a nix expert but my understanding is that this is typically done with overlays. So you can, say, swap out openmpi for mpich, but mpich requires a different version of hwloc that conflicts with the one defined in some othe
42.
by tgamblin 4y ago
Sorry to hear this. We have a lot of connections with the high energy physics community, which is why ROOT and Gaudi are even in Spack to begin with. There is an #hep channel on https://slack.spack.io , and we talk to those folk
43.
by tgamblin 4y ago
The Spack DSL for defining versions, options, etc. is declarative. That part of a package exposes options to the solver and very much allows reuse, in the sense that the same package can be built many different ways, and even with differ
44.
by tgamblin 4y ago
Main differences with Nix: * Spack has a dependency solver (concretizer). nixpkgs is managed by humans who do the dependency solving for you over time. What this means practically is that you can install 5 versions of some package with di
45.
by tgamblin 4y ago
I'd love to have both of these, to be honest.
46.
by tgamblin 4y ago
We have a guide for this written by Adam Stewart, probably our most prolific (package) contributor: * https://spack.readthedocs.io/en/latest/replace_conda_homebre... The thing you'll likely notice most about
47.
by tgamblin 4y ago
If I have to pick one difference, the fundamental one is that Spack does dependency resolution with a solver, while EB does not. So, in Spack, you write a package.py file (like say the one for gromacs: https://github.com/spa
48.
by tgamblin 4y ago
Original author here -- since I know that people click the comments to decide whether to read further, here's a (biased?) summary: Spack is aimed at end users, developers, and admins. It's used primarily in HPC at the moment but i
49.
by tgamblin 4y ago
Have you looked at Spack ( https://github.com/spack/spack )? Disclaimer: I lead the project. Spack essentially is nix with dependency resolution. spack packages can have conditional (nearly) anything: versions, options
50.
GitHub announces stance on sha256 stability(github.blog)
18 points by tgamblin 4y ago|2 comments
51.
by tgamblin 4y ago
Spack installs the software and generates the modules (you can customize how). See https://spack-tutorial.readthedocs.io/en/latest/tutorial_mod...
52.
by tgamblin 4y ago
Co-author/spack guy/occasional frequenter of Nix fora here. Aside from what p4ul said above, the main architectural differences between Nix and Spack are: 1. Spack has a dependency solver (the "concretizer"), Nix doe
53.
Using Answer Set Programming for HPC Dependency Solving(arxiv.org)
3 points by tgamblin 4y ago|0 comments
54.
Using Answer Set Programming for Dependency Solving in Spack(arxiv.org)
1 points by tgamblin 4y ago|0 comments
55.
Nuclear Weapons Technology 101 [pdf](cgsr.llnl.gov)
3 points by tgamblin 4y ago|0 comments
56.
Public Binaries for Spack(spack.io)
1 points by tgamblin 4y ago|0 comments
57.
by tgamblin 4y ago
You can do this kind of work and also get paid decently at a national lab. For example, LLNL is hiring!
58.
by tgamblin 5y ago
All of this is true, but I’ll just be nitpicky to make a point: > Does a future event's processing circumstances maybe depend on all events received up until now? In a parallel prefix sum, the final sum does depend on all prior inpu
59.
by tgamblin 5y ago
I did a year of server-side web dev from 2002-2003, then decided I wanted to do something different. I went back to grad school, got my Ph.D., and now I’m in high performance computing.
60.
by tgamblin 5y ago
Not a nuclear war simulation, but what you’re asking about is the mission of NARAC at LLNL: https://narac.llnl.gov NARAC monitors and predicts the spread of wind/water carried nuclear, biological, chemical, and other hazard

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