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2fbedb9402
Update the README.md to document what gets returned.
We might in the future split these up into other attrsets but I don't see a usecase for that at the moment.
(cherry picked from commit 07916fc3fd)
49 lines
2.4 KiB
Markdown
49 lines
2.4 KiB
Markdown
# Nixpkgs CI evaluation
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The code in this directory is used by the [eval.yml](../../.github/workflows/eval.yml) GitHub Actions workflow to evaluate the majority of Nixpkgs for all PRs, effectively making sure that when the development branches are processed by Hydra, no evaluation failures are encountered.
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Furthermore it also allows local evaluation using:
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```
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nix-build ci -A eval.baseline
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```
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The most important two arguments are:
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- `--arg evalSystems`: The set of systems for which `nixpkgs` should be evaluated.
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Defaults to the four official platforms (`x86_64-linux`, `aarch64-linux`, `x86_64-darwin` and `aarch64-darwin`).
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Example: `--arg evalSystems '["x86_64-linux" "aarch64-darwin"]'`
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- `--arg quickTest`: Enables testing a single chunk of the current system only for quick iteration.
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Example: `--arg quickTest true`
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The following arguments can be used to fine-tune performance:
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- `--max-jobs`: The maximum number of derivations to run at the same time.
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Only each [supported system](../supportedSystems.json) gets a separate derivation, so it doesn't make sense to set this higher than that number.
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- `--cores`: The number of cores to use for each job.
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Recommended to set this to the amount of cores on your system divided by `--max-jobs`.
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- `--arg chunkSize`: The number of attributes that are evaluated simultaneously on a single core.
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Lowering this decreases memory usage at the cost of increased evaluation time.
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If this is too high, there won't be enough chunks to process them in parallel, and will also increase evaluation time.
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The default is 5000.
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Example: `--arg chunkSize 10000`
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Note that 16GB memory is the recommended minimum, while with less than 8GB memory evaluation time suffers greatly.
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## Local eval with rebuilds / comparison
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To compare two commits locally, first run the following on the baseline commit:
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```
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BASELINE=$(nix-build ci -A eval.baseline --no-out-link)
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```
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Then, on the commit with your changes:
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```
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nix-build ci -A eval.full --arg baseline $BASELINE
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```
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Keep in mind to otherwise pass the same set of arguments for both commands (`evalSystems`, `quickTest`, `chunkSize`).
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Running this command will evaluate the difference between the baseline statistics and the ones at the time of running the command.
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From that difference, it will produce a human-readable report in `$out/step-summary.md`.
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If no packages were added or removed, then performance statistics will also be generated as part of this report.
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