Systems++

Learning to Learn: Travel

Sun, 03 May 2026 00:00:00 +0000

Travel can be an opportunity to see and explore new cultures. I’ve had the chance to do a lot of traveling with work. Here are some of the things I’ve learned along the way.

Using my iPad as a Second Monitor with KDE Plasma

Thu, 30 Oct 2025 10:58:14 -0500

When traveling it is sometimes helpful to have access to a second monitor. An iPad does a passable job for this when your traveling and just need a little more screen real-estate.

About Me

Tue, 17 Jun 2025 00:00:00 +0000

I am an Assistant Computer Scientist at Argonne National Laboratory under Franck Cappello. My particular research interests are lossy compression, science data and evaluation for AI, distributed systems, and systems programming.

Spack on Perlmutter

Thu, 11 Jul 2024 00:00:00 +0000

configure spack for NERSC Perlmutter

Install podman on Windows, MacOS, and Linux

Mon, 01 Jan 2024 00:00:00 +0000

how to install the podman container engine on various operating systems

Installing My Server Fully Remotely

Thu, 23 Nov 2023 12:17:00 -0500

I run a small tower server in my house to provide services that I use for software development, recently CentOS-8-Stream reached end of life. Since this server distribution doesn’t support in-place updates, updating requires reinstalling with a new version of the CentOS-9-Stream. This post documents the challenges that I hit along the way.

What to support if you are supporting

Tue, 12 Sep 2023 00:00:00 +0000

Dependencies matter a lot in terms of who can easily install and use your software. However there are trade-offs in what features are provided by each version and the availability of these versions. This presents an opinionated take on what these trade-offs are so one can know what can be widely supported.

Dethroning LaTeX: What Would It Take?

Sun, 02 Jul 2023 00:00:00 +0000

As an academic, you write a lot of papers. If you contribute to the disciplines of Math, Computer Science, or some domains of physical sciences, you’ve probably used LaTeX – a typesetting language – through a tool like Overleaf. What’s nice about LaTeX is that it attempts to separate concerns: Authors with minimal effort can port the text and structure of a document from one style to another. It generally produces much more ascetically pleasing output by default than what most authors would do on their own. It handles formatting of three things that generally are extremely frustrating in other tools: citations/bibliography, cross-references, footnotes/endnotes, equations, and embedded code listings. When used with a source control like Git it provides one of the best change review and tracking mechanisms of any document platform.

Spack on Ubuntu 20.04

Thu, 25 May 2023 00:00:00 +0000

general guidance for using spack on Ubuntu 20.04

How I Work: Killer Libraries

Mon, 24 Apr 2023 00:00:00 +0000

Most successful langauges have a “killer” features that motivates

In my previous post, I commented on the tools that I use for software development, but I didn’t talk about either the process of choosing a language or the libraries within a language that I use most frequently. This post expands on how I work within a language and specific “killer” libraries that I use most and how they compare to facililties that I know from other languages.

Refactoring CI/CD for a Moderately Large C++ Code Base

Mon, 24 Apr 2023 00:00:00 +0000

CI/CD is a critical, but difficult to get right part of software engineering. You often want to test multiple distributions, multiple compilers on each commit, and you want that to be as fast as reasonably possible. This gets more complicated when you have large dependency trees that you want to remain consistent. Recently, I adapted the CI/CD system for a project that I maintain LibPressio to use Dagger – a programmatic way to do CI/CD portable-ally across runner environments which made it easier to run our tests and verify correctness.

How I work: The Tools I Use

Tue, 14 Mar 2023 00:00:00 +0000

From time to time I get a question of what tools I use for what jobs. Here the tools I use to get things done:

External Clang-Tidy Modules! C++ Refactoring for the Common Project

Fri, 10 Mar 2023 00:00:00 +0000

Clang style refactoring has been something I’ve been admiring from afar for quite a while now. However for a user to actually use it, it has previously required forking llvm to be able to use it in a reasonable fashion because of things like the hack in clang used to locate the resource directory or other fragile hacks like LD_PRELOAD.

Learning to Learn: Software Teams

Thu, 09 Feb 2023 00:00:00 +0000

Outside of school very seldom in software development will you completely work alone on a project. Leading and being an effective member of a software team will be critical to your success in this field. However each team and project is different. Some projects have a high iteration cost because testing could cause people to die (e.g. bugs in rocket guidance systems in manned space flight), testing could be lengthy (e.g. if you need to manufacture a physical thing), or expensive resources are consumed (e.g. issues that only manifest when using 1000 nodes) and have to be more planning focused. Other line of business or research applications can afford to be more iterative. Knowing which situation you are in is key to crafting your process to be more effective. Regardless, there are some timeless principles of teams which are important to consider when working in or leading a team. In this post, I will highlight what research says makes effective teams and highlight how one popular approach implements these principles.

Learning to Learn: Software Development on Linux

Sun, 22 Jan 2023 08:00:00 -0500

What is software development? At a most basic level, it is the activity of using a programming language to achieve some set of goals over time. It includes everything from scripts that a graduate student might write to analyze some data to massive systems that control aircraft. As our world continues to progress technically, software development will likely become even more commonplace than it is now. In this post, I aim to provide a comprehensive overview of how one can develop software efficiently using free and open source tools on Linux.

Learning to Learn: Task Management, Time Tracking, and Journaling

Sun, 22 Jan 2023 08:00:00 -0500

A few of the key things that you will need as you need as a professional are the ability to manage tasks, understand how you spend your time, and improve your own processes. For me and many others, journaling, task managers, and time trackers help you answer these important questions.

Learning to Learn: GDB

Sun, 22 Jan 2023 00:00:00 +0000

GDB is a powerful tool that is underutilized by most programmers that I’ve met. It can tell you the state of one or more running or crashed programs, and even manipulate the memory of a running process. It is an invaluable tool for understanding what is going wrong with your programs.

Learning to Learn: MPI

Sun, 22 Jan 2023 00:00:00 +0000

MPI is the de-facto standard way to write distributed programs that run on super computers. Many have tried to replace it, but so far none of them have succeeded. Learning to use it successfully, will enable you to write powerful distributed programs.

Refactoring With Clang Query

Wed, 28 Dec 2022 00:00:00 +0000

Have you ever wanted to identify a list of files that would need modifications to adopt a new API? Clang-Query can make this much easier. I recently wanted to introduce a set of helper functions to simplfy an aspect of compressor configuation in LibPressio. But first, I needed to know what modules were effected.

Three Neat Things I Did With Julia

Thu, 15 Dec 2022 00:00:00 +0000

In the past, I’ve written pretty glowingly about Julia. It’s been a few years since I first used Julia in 2019, and it hasn’t completely replaced Python for me. However, I wanted to share a few neat projects that I’ve done using it which would have been much more painful without it, and share what I think now about what I wrote in 2019.

Debugging Inconsistent Network Performance

Wed, 14 Dec 2022 00:00:00 +0000

High-performance network interconnects, such as Infiniband, are common in high performance computing environments. Recently, my colleagues, and I ran a series of experiments on the Cooley system at the Argonne Leadership Computing Facility. For one set of experiments, the network performance was consistent and fast, but for the others we periodically had poor performance. Up until this point in my work, I had not directly used or configured network libraries below this layer. This post summarizes the steps we took to investigate the performance.

Learning to Learn: CMake

Tue, 15 Nov 2022 05:00:00 -0500

CMake is the de-facto C++ build system used by an overwhelming number of C++ projects. Even if you personally favor more modern alternatives such as Meson, Bazel, or Pants, if you ever pull in a 3rd party dependency, there is a good chance that it uses CMake so knowing enough about CMake to understand it is worth knowing.

Spack on Crusher

Wed, 26 Oct 2022 00:00:00 +0000

Configure spack for ORNL OLCF Crusher

Spack on Summit

Tue, 25 Oct 2022 00:00:00 +0000

configure spack on ORNL OLCF Summit

How to export a C API from a C++ code

Mon, 24 Oct 2022 00:00:00 +0000

C is the lingua franca of platform APIs. Most if not all languages provide a mechanism to import APIs from C because they need to do so in order to support the operating system. But given the expressiveness of C++, its often nice to write this code in C++ instead; here’s how to do that sanely.

How to add a dependency in CMake

Wed, 19 Oct 2022 00:00:00 +0000

A short verison of how to work with dependencies in CMake

Suggestions for the Design of Computational Experiments

Tue, 18 Oct 2022 08:00:00 -0500

So you want to do empirical computer science? Doing good science is difficult. It requires discipline and attention to detail. However there are strategies that can help you focus on answering the questions you can attempt to answer. First you should ask, “is this a scientific question?” Not all questions are scientific questions. Questions about aesthetics, values, ethics are not science questions. “Is A better than B?” is not a scientific question, it’s a question of values. Questions of values require trade offs, and while important can’t be solved with the scientific method of stating assumptions, posing questions, designing experiments, collecting data, and interpreting results. “Can method A achieve more flops than method B in a given specific context?” Is more of a scientific question.

Updating LibPressio with Spack

Tue, 13 Sep 2022 00:00:00 +0000

how can you update your copy of libpressio via spack?

Thoughts on Dependencies for Scientific Software

Wed, 20 Jul 2022 00:00:00 -0500

Modern software does not exist in a vacuum, developers always rely on other developers or engineers to provide aspects of their systems. Even if you write hello world in your programming language of your choice you likely still depend on the standard library from your language. Even if you were to write hello world in the raw binary format of your assembly language, you still depend on the operating system. Even if you wrote your own uni-kernel to produce hello world on the console, you likely rely on vendor provided firmware to initialize the program or memory. And if you are one of the blessed few who can completely fabricate your own hardware and don’t need to rely on vendor provided firmware, you likely don’t have time or expertise to write efficient higher level systems and need others to provide software to run on your hardware. Therefore the question is not will you use dependencies, but how will you use them responsibly.

Shortcut Guide for Configuring Spack for a New HPC System