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Parallel copperlists#942

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gbin merged 23 commits into
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gbin/checkpoints
Mar 21, 2026
Merged

Parallel copperlists#942
gbin merged 23 commits into
masterfrom
gbin/checkpoints

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@gbin

@gbin gbin commented Mar 20, 2026 •
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Summary

This is a feature that was in concepts for a long while: push the bandwidth up for copper by parallelizing the copperlists while preserving the overall serial shape of the execution in terms of causality.

Related issues

  • Closes #

Changes

Testing

  • just fmt
  • just lint
  • just test
  • optional full just std-ci (if std/runtime paths are impacted)
  • optional full just nostd-ci (if embedded/no_std paths are impacted)
  • Other (please specify):

pro-tip: just with no parameters in the root defaults to just fmt, just lint, and just test.

Checklist

  • I have updated docs or examples where needed
  • I have added or updated tests where needed
  • I have considered platform impact (Linux/macOS/Windows/embedded)
  • I have considered config/logging changes (if applicable)
  • This change is not a breaking change (or I documented it below)

Breaking changes (if any)

Additional context

@gbin gbin added enhancement New feature or request include in changelog labels Mar 20, 2026
@gbin gbin marked this pull request as draft March 20, 2026 20:09
@gbin gbin marked this pull request as ready for review March 20, 2026 20:09
@gbin gbin force-pushed the gbin/checkpoints branch from 91daf41 to 259b42d Compare March 20, 2026 21:06
@gbin gbin changed the title WIP: parallel copperlists Parallel copperlists Mar 21, 2026
@gbin

gbin commented Mar 21, 2026 •
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We tested 2 architectures in this PR:

  • stage pipeline: a pool is executing stage by stage any unlocked workload.
    - serial: 131.474s
    - parallel: 10.016s
  • checkpoints: a thread goes through 1 CL and waits if it is going too fast before passing another one
    - serial: 131.013s
    - parallel: 12.902s

@gbin

gbin commented Mar 21, 2026

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Added a couple experiment an having a spsc between the stages is slightly better:
Current Config

Branch Runs (s) Avg (s) Range (s)
gbin/checkpoints 7.801, 13.386, 9.404 10.197 5.585
gbin/checkpoints_spsc 7.805, 11.228, 11.217 10.083 3.423
gbin/checkpoints_spsc_custom 7.962, 15.499, 10.284 11.248 7.537

No Logging
I temporarily disabled global task logging plus the frames task logging in temp worktrees only, ran the same 3x round-robin, then restored those worktrees to a clean state.

Branch Runs (s) Avg (s) Range (s)
gbin/checkpoints 7.606, 7.809, 7.685 7.700 0.203
gbin/checkpoints_spsc 7.641, 7.653, 7.651 7.648 0.012
gbin/checkpoints_spsc_custom 7.674, 7.725, 7.767 7.722 0.093

@gbin

gbin commented Mar 21, 2026 •
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ok with the fsync + small bug fix on the mmap, we shaved half the stdev between runs:

  • baseline-clean: mean 10.399s, stdev 1.309s, range 3.390s
  • fsync-clean: mean 11.847s, stdev 0.784s, range 2.124s

@gbin
Merge remote-tracking branch 'origin/master' into gbin/checkpoints
7d41dd0 
# Conflicts:
#	core/cu29/Cargo.toml
#	core/cu29_runtime/Cargo.toml
@gbin

gbin commented Mar 21, 2026

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urgh, as a last pass before merging that, checking if we did not added any overhead on the base case .. we did:

  • master run 1: 248 ns mean, 6,822,755 samples
  • master run 2: 250 ns mean, 6,754,493 samples
  • gbin/checkpoints run 1: 375 ns mean, 5,747,314 samples
  • gbin/checkpoints run 2: 369 ns mean, 5,889,504 samples

@gbin gbin merged commit 234feda into master Mar 21, 2026
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@gbin gbin deleted the gbin/checkpoints branch March 21, 2026 17:53
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