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Urbit

Vere Profiling

Uncover and visualize performance bottlenecks in the runtime

August 26, 2022

Reward: 1 star

ID: A0180

Grantee(s): ~pontus-fadpun

CompletedApprenticeshipDev: Core

Vere Profiling Apprenticeship

Urbit currently has two profilers: a tracing profiler and a sampling profiler. The tracing profiler writes a stack trace to <pier>/.urb/put/trace. To enable:

$ urbit -j <pier>

The sampling profiler uses SIGPROF to build up a set of data points detailing the code paths that the runtime spends the most time executing. To enable:

$ cd <urbit_repo>/pkg/urbit
$ CPU_DEBUG=1 ./configure
$ make
$ build/urbit -P <pier>

This project will add additional profiling capabilites to Vere by using well-known profiling tools like dtrace, bpftrace, and similar to develop more nuanced insights into the performance bottlenecks in Vere. Upon identification, the bottlenecks will be addressed where possible, leading to a more performant runtime. Exploration of alternative profiling techniques like causal profiling is encouraged.

Deliverables

  • Integration of additional profiling tooling into Vere;
  • list of performance bottlenecks;
  • and patches addressing as many of the performance bottlenecks as possible.

Prerequisites

  • Proficiency in C
  • Experience with profiling tools like dtrace (macOS, FreeBSD), bpftrace (Linux)

Educational Outcomes for the Apprentice

The apprentice will:

  • learn about the current state of profiling in Vere;
  • integrate new tooling into Vere;
  • and address any performance bottlenecks discovered.

Responsibilities of the Mentor

The mentor will:

  • provide technical direction via recurring meetings and DM;
  • review code;
  • and help the apprentice prepare the changes for release.

Duration and Compensation

The expected duration is two months. Compensation is 1 star upon sucessful completion of the apprenticeship.