Henrique Fingler

Yineng Yan, William Ruys, Hochan Lee et al.

As the complexity and scale of modern parallel machines continue to grow, programmers increasingly rely on composition of software libraries to encapsulate and exploit parallelism. However, many libraries are not designed with composition in mind and assume they have exclusive access to all resources. Using such libraries concurrently can result in contention and degraded performance. Prior solutions involve modifying the libraries or the OS, which is often infeasible. We propose Virtual Library Contexts (VLCs), which are process subunits that encapsulate sets of libraries and associated resource allocations. VLCs control the resource utilization of these libraries without modifying library code. This enables the user to partition resources between libraries to prevent contention, or load multiple copies of the same library to allow parallel execution of otherwise thread-unsafe code within the same process. In this paper, we describe and evaluate C++ and Python prototypes of VLCs. Experiments show VLCs enable a speedup up to 2.85x on benchmarks including applications using OpenMP, OpenBLAS, and LibTorch. Source code of VLCs is available at https://github.com/pecos/Virtual-Library-Context.

Trinabh Gupta, Henrique Fingler, Lorenzo Alvisi et al.

Emails today are often encrypted, but only between mail servers---the vast majority of emails are exposed in plaintext to the mail servers that handle them. While better than no encryption, this arrangement leaves open the possibility of attacks, privacy violations, and other disclosures. Publicly, email providers have stated that default end-to-end encryption would conflict with essential functions (spam filtering, etc.), because the latter requires analyzing email text. The goal of this paper is to demonstrate that there is no conflict. We do so by designing, implementing, and evaluating Pretzel. Starting from a cryptographic protocol that enables two parties to jointly perform a classification task without revealing their inputs to each other, Pretzel refines and adapts this protocol to the email context. Our experimental evaluation of a prototype demonstrates that email can be encrypted end-to-end \emph{and} providers can compute over it, at tolerable cost: clients must devote some storage and processing, and provider overhead is roughly 5 times versus the status quo.