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| 1 | +# 2024-05-21 Triage Log |
| 2 | + |
| 3 | +Fairly quiet week with the exception of a very large improvement coming from the switch to `rust-lld` on nightly Linux. This can have very large impacts on benchmarks where linking dominates the build time (e.g., `ripgrep`, `exa`, small binaries like `hello-world`). Aside from that change, there were a few small regressions that were either deemed worth it or are still being investigated. |
| 4 | + |
| 5 | +Triage done by **@rylev**. |
| 6 | +Revision range: [9105c57b..1d0e4afd](https://perf.rust-lang.org/?start=9105c57b7f6623310e33f3ee7e48a3114e5190a7&end=1d0e4afd4cac09078e12a232508c3e9f8d42535d&absolute=false&stat=instructions%3Au) |
| 7 | + |
| 8 | +**Summary**: |
| 9 | + |
| 10 | +| (instructions:u) | mean | range | count | |
| 11 | +|:----------------------------------:|:------:|:---------------:|:-----:| |
| 12 | +| Regressions ❌ <br /> (primary) | 0.7% | [0.1%, 2.5%] | 30 | |
| 13 | +| Regressions ❌ <br /> (secondary) | 0.5% | [0.2%, 0.8%] | 5 | |
| 14 | +| Improvements ✅ <br /> (primary) | -30.4% | [-71.7%, -0.4%] | 35 | |
| 15 | +| Improvements ✅ <br /> (secondary) | -25.6% | [-70.9%, -0.5%] | 75 | |
| 16 | +| All ❌✅ (primary) | -16.1% | [-71.7%, 2.5%] | 65 | |
| 17 | + |
| 18 | + |
| 19 | +4 Regressions, 1 Improvement, 4 Mixed; 2 of them in rollups |
| 20 | +66 artifact comparisons made in total |
| 21 | + |
| 22 | +#### Regressions |
| 23 | + |
| 24 | +Add x86_64-unknown-linux-none target [#125023](https://github.com/rust-lang/rust/pull/125023) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=c45e831d8fcd33d656047ba97d263c4b91a00735&end=31026b7fe3e510a646eddeda838d1f0859f892e7&stat=instructions:u) |
| 25 | + |
| 26 | +| (instructions:u) | mean | range | count | |
| 27 | +|:----------------------------------:|:----:|:------------:|:-----:| |
| 28 | +| Regressions ❌ <br /> (primary) | 0.6% | [0.2%, 1.0%] | 3 | |
| 29 | +| Regressions ❌ <br /> (secondary) | 0.4% | [0.4%, 0.4%] | 3 | |
| 30 | +| Improvements ✅ <br /> (primary) | - | - | 0 | |
| 31 | +| Improvements ✅ <br /> (secondary) | - | - | 0 | |
| 32 | +| All ❌✅ (primary) | 0.6% | [0.2%, 1.0%] | 3 | |
| 33 | +- Noise |
| 34 | + |
| 35 | + |
| 36 | +Rollup of 6 pull requests [#125144](https://github.com/rust-lang/rust/pull/125144) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=3cb0030fe9de01eeacb7c03eeef0c51420798cfb&end=ade234d5743795423db6cc7cd52541390a088eab&stat=instructions:u) |
| 37 | + |
| 38 | +| (instructions:u) | mean | range | count | |
| 39 | +|:----------------------------------:|:----:|:------------:|:-----:| |
| 40 | +| Regressions ❌ <br /> (primary) | 0.5% | [0.2%, 1.2%] | 3 | |
| 41 | +| Regressions ❌ <br /> (secondary) | - | - | 0 | |
| 42 | +| Improvements ✅ <br /> (primary) | - | - | 0 | |
| 43 | +| Improvements ✅ <br /> (secondary) | - | - | 0 | |
| 44 | +| All ❌✅ (primary) | 0.5% | [0.2%, 1.2%] | 3 | |
| 45 | + |
| 46 | + |
| 47 | +Update `expr` matcher for Edition 2024 and add `expr_2021` nonterminal [#123865](https://github.com/rust-lang/rust/pull/123865) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=1a7397988684934ae01a71f524bdfff24895d8cc&end=9b75a4388143a163b77fa7d458e4aa4dd34ac1bd&stat=instructions:u) |
| 48 | + |
| 49 | +| (instructions:u) | mean | range | count | |
| 50 | +|:----------------------------------:|:----:|:------------:|:-----:| |
| 51 | +| Regressions ❌ <br /> (primary) | 0.2% | [0.2%, 0.3%] | 5 | |
| 52 | +| Regressions ❌ <br /> (secondary) | 0.5% | [0.2%, 1.7%] | 7 | |
| 53 | +| Improvements ✅ <br /> (primary) | - | - | 0 | |
| 54 | +| Improvements ✅ <br /> (secondary) | - | - | 0 | |
| 55 | +| All ❌✅ (primary) | 0.2% | [0.2%, 0.3%] | 5 | |
| 56 | +- It seems the primary benchmark affected by this html5ever seems to spend lots of time in expand_crate which could be impacted by this change. |
| 57 | +- Asked authors and reviewer whether this is worth an investigation or not. |
| 58 | + |
| 59 | + |
| 60 | +Update `unexpected_cfgs` lint for Cargo new `check-cfg` config [#125219](https://github.com/rust-lang/rust/pull/125219) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=be71fd477243f253a735bb35e0cd23cc528cf30a&end=b92758a9aef1cef7b79e2b72c3d8ba113e547f89&stat=instructions:u) |
| 61 | + |
| 62 | +| (instructions:u) | mean | range | count | |
| 63 | +|:----------------------------------:|:----:|:------------:|:-----:| |
| 64 | +| Regressions ❌ <br /> (primary) | 0.8% | [0.2%, 2.5%] | 21 | |
| 65 | +| Regressions ❌ <br /> (secondary) | 0.2% | [0.2%, 0.2%] | 1 | |
| 66 | +| Improvements ✅ <br /> (primary) | - | - | 0 | |
| 67 | +| Improvements ✅ <br /> (secondary) | - | - | 0 | |
| 68 | +| All ❌✅ (primary) | 0.8% | [0.2%, 2.5%] | 21 | |
| 69 | +- Somewhat further fall out from https://github.com/rust-lang/rust/pull/124684. This adds additional output which will slow down benchmarks which emit this warning particularly often. |
| 70 | +- We're likely ok with this given this is the "unhappy path". |
| 71 | + |
| 72 | + |
| 73 | +#### Improvements |
| 74 | + |
| 75 | +Enable `rust-lld` on nightly `x86_64-unknown-linux-gnu` [#124129](https://github.com/rust-lang/rust/pull/124129) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=fa37db51ac2ba8d20eb88079cb3234d0072c5c3a&end=8af67ba01a1b1d95ff375b645ef5a395d3249e09&stat=instructions:u) |
| 76 | + |
| 77 | +| (instructions:u) | mean | range | count | |
| 78 | +|:----------------------------------:|:------:|:---------------:|:-----:| |
| 79 | +| Regressions ❌ <br /> (primary) | - | - | 0 | |
| 80 | +| Regressions ❌ <br /> (secondary) | - | - | 0 | |
| 81 | +| Improvements ✅ <br /> (primary) | -30.8% | [-71.8%, -0.5%] | 31 | |
| 82 | +| Improvements ✅ <br /> (secondary) | -25.6% | [-70.9%, -0.5%] | 75 | |
| 83 | +| All ❌✅ (primary) | -30.8% | [-71.8%, -0.5%] | 31 | |
| 84 | + |
| 85 | + |
| 86 | +#### Mixed |
| 87 | + |
| 88 | +Rollup of 7 pull requests [#125120](https://github.com/rust-lang/rust/pull/125120) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=bdfd941f4dcbe54e0283433ac970febf4092fa6a&end=ac385a5af6d9fa8399a0cec799833cd28324abf8&stat=instructions:u) |
| 89 | + |
| 90 | +| (instructions:u) | mean | range | count | |
| 91 | +|:----------------------------------:|:-----:|:--------------:|:-----:| |
| 92 | +| Regressions ❌ <br /> (primary) | 0.2% | [0.2%, 0.2%] | 2 | |
| 93 | +| Regressions ❌ <br /> (secondary) | 0.5% | [0.3%, 1.0%] | 12 | |
| 94 | +| Improvements ✅ <br /> (primary) | - | - | 0 | |
| 95 | +| Improvements ✅ <br /> (secondary) | -0.4% | [-0.5%, -0.4%] | 2 | |
| 96 | +| All ❌✅ (primary) | 0.2% | [0.2%, 0.2%] | 2 | |
| 97 | +- Caused by https://github.com/rust-lang/rust/pull/125088. Asked the author/reviewers whether this is worth following up on. |
| 98 | + |
| 99 | + |
| 100 | +Remove bound checks from `BorrowedBuf` and `BorrowedCursor` methods [#123786](https://github.com/rust-lang/rust/pull/123786) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=698293518de49ac79eb7874e97557f8e2eabda06&end=959a67a7f2215d80b55e765d6c4b3f5a711ad484&stat=instructions:u) |
| 101 | + |
| 102 | +| (instructions:u) | mean | range | count | |
| 103 | +|:----------------------------------:|:-----:|:--------------:|:-----:| |
| 104 | +| Regressions ❌ <br /> (primary) | 0.8% | [0.8%, 0.8%] | 1 | |
| 105 | +| Regressions ❌ <br /> (secondary) | 1.3% | [1.3%, 1.3%] | 1 | |
| 106 | +| Improvements ✅ <br /> (primary) | -1.7% | [-1.7%, -1.7%] | 1 | |
| 107 | +| Improvements ✅ <br /> (secondary) | - | - | 0 | |
| 108 | +| All ❌✅ (primary) | -0.5% | [-1.7%, 0.8%] | 2 | |
| 109 | +- Noise |
| 110 | + |
| 111 | + |
| 112 | +optimize inplace collection of Vec [#123878](https://github.com/rust-lang/rust/pull/123878) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=d84b9037541f45dc2c52a41d723265af211c0497&end=12075f04e677de64f740687f601114e2a21e09ca&stat=instructions:u) |
| 113 | + |
| 114 | +| (instructions:u) | mean | range | count | |
| 115 | +|:----------------------------------:|:------:|:---------------:|:-----:| |
| 116 | +| Regressions ❌ <br /> (primary) | 1.4% | [0.3%, 2.9%] | 3 | |
| 117 | +| Regressions ❌ <br /> (secondary) | 0.3% | [0.2%, 0.3%] | 2 | |
| 118 | +| Improvements ✅ <br /> (primary) | -22.7% | [-37.4%, -0.4%] | 5 | |
| 119 | +| Improvements ✅ <br /> (secondary) | - | - | 0 | |
| 120 | +| All ❌✅ (primary) | -13.7% | [-37.4%, 2.9%] | 8 | |
| 121 | +- Improvements vastly outweigh the regressions which seemed to have returned to baseline after this PR. |
| 122 | + |
| 123 | + |
| 124 | +Follow-up fixes to `report_return_mismatched_types` [#123812](https://github.com/rust-lang/rust/pull/123812) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=1d0e4afd4cac09078e12a232508c3e9f8d42535d&end=e8753914580fb42554a79a4b5c5fb4cc98933231&stat=instructions:u) |
| 125 | + |
| 126 | +| (instructions:u) | mean | range | count | |
| 127 | +|:----------------------------------:|:-----:|:--------------:|:-----:| |
| 128 | +| Regressions ❌ <br /> (primary) | 1.1% | [0.6%, 1.8%] | 3 | |
| 129 | +| Regressions ❌ <br /> (secondary) | 0.2% | [0.1%, 0.2%] | 6 | |
| 130 | +| Improvements ✅ <br /> (primary) | - | - | 0 | |
| 131 | +| Improvements ✅ <br /> (secondary) | -1.1% | [-1.1%, -1.1%] | 2 | |
| 132 | +| All ❌✅ (primary) | 1.1% | [0.6%, 1.8%] | 3 | |
| 133 | +- Single benchmark with a large regression. Asked author to investigate. |
| 134 | + |
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