CS Colloquium

Computer Science can be a high paying field but it doesn't have to be! In this talk Cooper Quintin, Senior Staff Technologist at the Electronic Frontier Foundation, will examine the career of a public interest technologist. This talk will explore the ways one can use their computer science skills to make the world a better place. The talk will finish with career options available to hackers besides working for the military industrial complex or big tech. Cooper will also share stories from his time as a public interest technologist.

As we cram billion of transistors into a chip, and build computers with thousands of such chips, the probability of system state bits transiently getting corrupted due to system noise and high energy particle strikes goes up. Such "soft errors" factors are exacerbated by manufacturing variability that is higher in smaller lithographies.

Many types of software-based error detectors have been proposed to detect these soft errors and trigger recomputation from state checkpoints.  Unfortunately, most of these detection schemes introduce unacceptable computational overheads and also have unacceptably high false positive rates.

In one line of work, we have ameliorated this situation by focusing on applications such as stencils.  In this domain, we guarantee near 100% detection based on rigorous floating-point error analysis based on affine arithmetic.  We also reduce overheads by covering multiple steps of the stencil application per detector deployment.

The main take-away message is that system resilience solutions developed with attention to higher accuracy and lower overheads may prove to be the inevitable safety net based on which designers attempt to reduce energy consumption in this period of ending Moore's law.

The presentation will be split into several pieces - all focused on Enterprise Technology application(s) for a fictitious company.  The first part of the presentation will set the context of what we do - analyze, design, develop and implement Enterprise Technology to enable eCommerce, Supply Chain, ERP and Business Intelligence.  This will be a high-level overview to establish context.  After that we're going to present a pro-forma project focused on B2B Supply Chain enablement for a fictitious logistics company.  We'll discuss the need to design and develop a custom solution as there was no "out of the box" solution suitable to the problem set.  After that we'll discuss the analysis phase of the project (gathering requirements), the design phase (technical design / enterprise architecture), the execution of the project (Agile Sprint Plan), the deployment of the solution and the implementation of CICD to enable continuous updating and improvement.  All this will be presented mostly via graphics with a minimum of text so the concepts will be simpler to grasp.

Performance clearly matters to users. For example, the most common software update on the AppStore is "Bug fixes and performance enhancements." Now that Moore's Law has ended, programmers have to work hard to get high performance for their applications. But why is performance hard to deliver?

I will first explain why current approaches to evaluating and optimizing performance don't work, especially on modern hardware and for modern applications. I then present two systems that address these challenges. Stabilizer is a tool that enables statistically sound performance evaluation, making it possible to understand the impact of optimizations and conclude things like the fact that the -O2 and -O3 optimization levels are indistinguishable from noise (sadly true).

Since compiler optimizations have run out of steam, we need better profiling support, especially for modern concurrent, multi-threaded applications. Coz is a new causal profiler that lets programmers optimize for throughput or latency, and which pinpoints and accurately predicts the impact of optimizations. Coz's approach unlocks previously unknown optimization opportunities. Guided by Coz, we improved the performance of Memcached (9%), SQLite (25%), and accelerated six other applications by as much as 68%; in most cases, this involved modifying less than 10 lines of code and took under half an hour (without any prior understanding of the programs!). Coz now ships as part of standard Linux distros (apt install coz-profiler).

More than just a mathematical curiosity, the quest to discover a new largest known prime requires the development of advanced computational techniques and the development of fault resilient software.  These computational techniques benefit a wide variety of applications from seismic analysis to large scale fluid dynamics.  The fault resilient methodologies benefit a wide range of application such as cryptography and deep space probe design.

The search for a new largest known prime has been ongoing for centuries.  In 1952, primality testing entered the realm of digital computers.  Computers have been used to construct proofs of primality for these enormous primes.  We have come a long way since the 1970s when the speaker, Landon Noll, as a student at Cal State East Bay (then CSUH), discovered a 6533-digit prime.  Today’s largest known prime is almost 25 million digits long!  Those seeking to break the record for the largest known prime have pushed the bounds of computing.

The calculations required to test extremely large numbers for primality must be fault resilient.  One must overcome compiler and assembler errors, errors introduced by the kernel, and hardware errors such as memory errors and CPU calculation errors.  The reason for such extreme programming is that the length of the primality search often exceeds the mean time to error of the calculating system.  The motivation for such extreme care lies in the fact that a slow and correct answer is infinitely preferable to a fast but incorrect answer. The world record goes neither to the fastest coder nor to the person with the fastest hardware but rather to the first result that is proven to be correct.

Knowledge of advanced mathematics is NOT required for this talk.