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Eight lanes, one shard list

gpur is the router that schedules the lab's jobs across its GPUs. A job declares the memory it needs and arrives as a list of shards; the router places each shard on a lane whose budget fits, and a lane that drops loses at most the shard it was running. This illustration replays a seeded placement across eight lanes labeled by class and lets you switch lanes off.

  • StatusIllustration
  • Published2026-10-06
  • Example textInvented
  • Embedded onThis page only
  • State in the address?job= ?off=
  • Codelib/explainers/gpur.ts
  • Protocolv1.0

IllustrationExplainer

Eight lanes, one shard list

A shard is the unit you can afford to lose.

lane, class, GBtick 01234561 office 16 GBbudget 13.92 office 16 GBbudget 13.93 off-site 16 GBbudget 13.94 off-site 16 GBbudget 13.95 office 12 GBbudget 9.96 office 8 GBbudget 5.97 client 8 GBbudget 5.98 client 6 GBbudget 3.9budget 3.9 below 5123456789101112queuednone
Job declares, GB
Lanes

Eligible lanes7 of 8

Shards placed12 of 12

Queued0

Replay length4 ticks

Every shard has a lane. A lane that drops now loses at most the shard it is running.

Illustration with a seeded replay, not live data. Lanes are labeled by class only. Budget is sticker memory minus the headroom the router adds and minus what the machine's own desktop already holds. The figure draws the rule; it is not an inventory of hardware.

The sentence it teaches

A shard is the unit you can afford to lose.

Method

  1. Eight lanes stand for GPUs in three classes: office, off-site and client. Each shows its sticker memory and the budget a job may declare.
  2. Budget is sticker memory minus the one gigabyte of headroom the router adds on top of a job's declared memory, minus about one gigabyte that a machine with a desktop session up already holds. Sticker memory is not the budget.
  3. The job declares a memory need. A lane is eligible when its budget is at least that number. Twelve shards are placed in order, each on the eligible lane that frees up first. Shard lengths come from a fixed seed, so every visitor sees the same replay.
  4. Switching a lane off makes it ineligible. Its shards move to the eligible lane that frees up first, or stay queued when no lane fits.

What this does not show

  • It does not show throughput, utilization or any measured figure. No number on this figure is a measurement.

State in the address

The figure keeps its state in the query string, so a particular view can be linked and the page still renders completely without it.

  • ?job= the memory the job declares, in gigabytes
  • ?off= the lanes switched off, by number, separated by dots

Cite this explainer

OptiVis Labs. Eight lanes, one shard list (explainer). 2026. https://optivisai.org/research/explainers/gpur

@misc{optivislabs2026explainergpur,
  title = {Eight lanes, one shard list (explainer)},
  author = {{OptiVis Labs}},
  year = {2026},
  month = oct,
  howpublished = {\url{https://optivisai.org/research/explainers/gpur}},
  note = {A shard is the unit you can afford to lose. Illustration with invented example text.}
}