triage report for this week.

Author: pnkfelix

triage/2024-10-21.md

@@ -1,8 +1,13 @@
 # 2024-10-21 Triage Log
 
-TODO: Summary
-
-Triage done by **@???**.
+Some tidy improvements from switching to next generation trait solver
+(solely for coherence checking) and from simplifying our dataflow
+analysis framework. There were some binary size regressions associated
+with PR 126557 (adding `#[track_caller]` to allocating methods of
+`Vec` and `VecDeque`), which I have handed off to T-libs to choose
+whether to investigate further.
+
+Triage done by **@pnkfelix**.
 Revision range: [5ceb623a..3e33bda0](https://perf.rust-lang.org/?start=5ceb623a4abd66e91e7959d25caaf0523f1a7f7c&end=3e33bda0326586a6e1e34d0f5c060ca6d116e6a4&absolute=false&stat=instructions%3Au)
 
 **Summary**:
@@ -35,6 +40,9 @@ stabilize `-Znext-solver=coherence` again [#130654](https://github.com/rust-lang
 | Improvements ✅ <br /> (secondary) | -0.3% | [-0.3%, -0.3%] | 3     |
 | All ❌✅ (primary)                 | -1.9% | [-4.5%, -0.2%] | 17    |
 
+* improvements are to bitmaps and nalgebra
+* (presumably due to their heavy use of trait machinery; though, skimming bitmaps, I'm not sure if I see heavy use of trait machinery there)
+* what else can I say, except, amazing!
 
 Remove `GenKillAnalysis` [#131481](https://github.com/rust-lang/rust/pull/131481) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=1f67a7aa8d5b30c43c28ed9b2621cf4b7b8bb963&end=d829780c4e4ef11f5e09c1c5ed9684c12aad7236&stat=instructions:u)
 
@@ -46,6 +54,10 @@ Remove `GenKillAnalysis` [#131481](https://github.com/rust-lang/rust/pull/131481
 | Improvements ✅ <br /> (secondary) | -0.9% | [-1.9%, -0.1%] | 19    |
 | All ❌✅ (primary)                 | -0.4% | [-0.7%, -0.2%] | 24    |
 
+* improvements are spread across html5ever, serde, cargo, libc, diesel, and bitmaps.
+* wow. I'm surprised `GenKillAnalysis` is a pessimization
+* (maybe this is a sign that our basic blocks tend to hold a small number of instructions...?)
+* anyway, overall amazing work.
 
 Rollup of 8 pull requests [#131792](https://github.com/rust-lang/rust/pull/131792) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=bed75e7c21e8d18bd536a0f7c9e479d2f6707db3&end=7342830c05ec0996e9e4b7df550b1043dca7829c&stat=instructions:u)
 
@@ -57,6 +69,8 @@ Rollup of 8 pull requests [#131792](https://github.com/rust-lang/rust/pull/13179
 | Improvements ✅ <br /> (secondary) | -     | -              | 0     |
 | All ❌✅ (primary)                 | -0.2% | [-0.2%, -0.2%] | 5     |
 
+* improvements are to incremental scenarios for stm32f4 (and one also for libc).
+
 
 #### Mixed
 
@@ -70,6 +84,9 @@ Add `#[track_caller]` to allocating methods of `Vec` & `VecDeque` [#126557](http
 | Improvements ✅ <br /> (secondary) | -0.2% | [-0.2%, -0.1%] | 4     |
 | All ❌✅ (primary)                 | 0.3%  | [0.0%, 0.5%]   | 26    |
 
+* based on a prior perf run (which predicted 16 primary regressions of roughly the same magnitude as observed here), the T-libs team had [already approved this PR](https://github.com/rust-lang/rust/pull/126557#issuecomment-2329482185) under the assumption that there wouldn't be a *runtime impact* from this.
+* there was a note from nnethercote that it isn't totally clear if the binary size increases were anticipated.
+* marking as triaged
 
 Rollup of 8 pull requests [#131690](https://github.com/rust-lang/rust/pull/131690) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=17a19e684cdf3ca088af8b4da6a6209d128913f4&end=9322d183f45e0fd5a509820874cc5ff27744a479&stat=instructions:u)
 
@@ -81,6 +98,9 @@ Rollup of 8 pull requests [#131690](https://github.com/rust-lang/rust/pull/13169
 | Improvements ✅ <br /> (secondary) | -     | -              | 0     |
 | All ❌✅ (primary)                 | -0.2% | [-0.8%, 0.4%]  | 3     |
 
+* regression to cargo opt-full; improvements to image and html5ever opt-full
+* briefly skimmed detailed results. nothing stood out.
+* not worth digging into further; marking as triaged
 
 Use `ThinVec` for PredicateObligation storage [#131422](https://github.com/rust-lang/rust/pull/131422) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=9ce3675b438aae22ef0c6147cde2003a418ab722&end=9618da7c9995a673af4841149ba2d1f53b69dd92&stat=instructions:u)
 
@@ -92,6 +112,8 @@ Use `ThinVec` for PredicateObligation storage [#131422](https://github.com/rust-
 | Improvements ✅ <br /> (secondary) | -0.3% | [-0.7%, -0.2%] | 23    |
 | All ❌✅ (primary)                 | -0.3% | [-0.7%, -0.2%] | 15    |
 
+* improvements outweigh regressions. (and reported performance matches what was anticipated via perf runs.)
+* marking as triaged
 
 optimize str.replace [#130223](https://github.com/rust-lang/rust/pull/130223) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=3a85d3fa785d95a7b7bcf4f160b67bffba7afd4a&end=86bd45979a964678b40b79156744f0057759d840&stat=instructions:u)
 
@@ -103,6 +125,9 @@ optimize str.replace [#130223](https://github.com/rust-lang/rust/pull/130223) [(
 | Improvements ✅ <br /> (secondary) | -0.4% | [-0.4%, -0.3%] | 6     |
 | All ❌✅ (primary)                 | 0.3%  | [-0.8%, 1.2%]  | 6     |
 
+* primary regressions to miscellaneous cargo and clap scenarios. (single primary improvement was to cargo incr-patched::println).
+* overall seems like minor regressions, potentially "just" instrumentation bias, compared to the expected benefit for microbenchmark reported in PR description.
+* marking as triaged.
 
 Rollup of 8 pull requests [#131934](https://github.com/rust-lang/rust/pull/131934) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=a2a1206811d864df2bb61b2fc27ddc45a3589424&end=8069f8d17a6c86a8fd881939fcce359a90c57ff2&stat=instructions:u)
 
@@ -114,6 +139,10 @@ Rollup of 8 pull requests [#131934](https://github.com/rust-lang/rust/pull/13193
 | Improvements ✅ <br /> (secondary) | -     | -              | 0     |
 | All ❌✅ (primary)                 | 0.1%  | [-0.2%, 0.3%]  | 3     |
 
+* primary regressions to helloworld (doc) and hyper (opt); primary improvement to libc (doc).
+* all the secondary regressions are to doc benchmarks, which led lqd to hypothesize that this is due to PR 131908 which changed the hash used for filename generation to sha256 since it should be stable going forward.
+* hyper history seems really noisy.
+* marking as triaged
 
 Update rustc-hash to version 2 but again [#131949](https://github.com/rust-lang/rust/pull/131949) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=de977a5acf210f7d71ff83f4b8bc42c274ce4ed9&end=662180b34d95f72d05b7c467b0baf4d23d36b1e1&stat=instructions:u)
 
@@ -125,41 +154,6 @@ Update rustc-hash to version 2 but again [#131949](https://github.com/rust-lang/
 | Improvements ✅ <br /> (secondary) | -0.9% | [-1.4%, -0.6%] | 13    |
 | All ❌✅ (primary)                 | -0.1% | [-0.5%, 0.2%]  | 18    |
 
-
-#### Untriaged Pull Requests
-
-- [#131949 Update rustc-hash to version 2 but again](https://github.com/rust-lang/rust/pull/131949)
-- [#131934 Rollup of 8 pull requests](https://github.com/rust-lang/rust/pull/131934)
-- [#131690 Rollup of 8 pull requests](https://github.com/rust-lang/rust/pull/131690)
-- [#131422 Use `ThinVec` for PredicateObligation storage](https://github.com/rust-lang/rust/pull/131422)
-- [#131263 Introduce SolverRelating type relation to the new solver](https://github.com/rust-lang/rust/pull/131263)
-- [#131111 Rollup of 4 pull requests](https://github.com/rust-lang/rust/pull/131111)
-- [#130223 optimize str.replace](https://github.com/rust-lang/rust/pull/130223)
-- [#130091 Rollup of 10 pull requests](https://github.com/rust-lang/rust/pull/130091)
-- [#129831 Rollup of 11 pull requests](https://github.com/rust-lang/rust/pull/129831)
-- [#129817 Rollup of 12 pull requests](https://github.com/rust-lang/rust/pull/129817)
-- [#129797 Try to reduce space usage in dist CI](https://github.com/rust-lang/rust/pull/129797)
-- [#129790 Bump to 1.83](https://github.com/rust-lang/rust/pull/129790)
-- [#129632 Rollup of 9 pull requests](https://github.com/rust-lang/rust/pull/129632)
-- [#129063 Apply size optimizations to panic machinery and some cold functions](https://github.com/rust-lang/rust/pull/129063)
-- [#128936 Support reading thin archives in ArArchiveBuilder](https://github.com/rust-lang/rust/pull/128936)
-- [#128443 Properly mark loop as diverging if it has no breaks](https://github.com/rust-lang/rust/pull/128443)
-- [#128357 Detect non-lifetime binder params shadowing item params](https://github.com/rust-lang/rust/pull/128357)
-- [#128301 Rollup of 3 pull requests](https://github.com/rust-lang/rust/pull/128301)
-- [#128299 Simplify the canonical clone method and the copy-like forms to copy](https://github.com/rust-lang/rust/pull/128299)
-- [#128169 Rollup of 5 pull requests](https://github.com/rust-lang/rust/pull/128169)
-- [#128155 Rollup of 8 pull requests](https://github.com/rust-lang/rust/pull/128155)
-- [#128104 Not lint pub structs without pub constructors intentionally](https://github.com/rust-lang/rust/pull/128104)
-- [#127998 Rollup of 9 pull requests](https://github.com/rust-lang/rust/pull/127998)
-- [#127865 Rollup of 8 pull requests](https://github.com/rust-lang/rust/pull/127865)
-- [#127537 Implement a first version of RFC 3525: struct target features](https://github.com/rust-lang/rust/pull/127537)
-- [#127528 Replace ASCII control chars with Unicode Control Pictures](https://github.com/rust-lang/rust/pull/127528)
-- [#127486 Rollup of 5 pull requests](https://github.com/rust-lang/rust/pull/127486)
-- [#127439 Uplift elaboration into `rustc_type_ir`](https://github.com/rust-lang/rust/pull/127439)
-- [#127172 Make `can_eq` process obligations (almost) everywhere](https://github.com/rust-lang/rust/pull/127172)
-- [#127096 Rollup of 11 pull requests](https://github.com/rust-lang/rust/pull/127096)
-
-#### Nags requiring follow up
-
-TODO: Nags
-
+* primary improvements to unicode-normalization and libc
+* primary regressions to typenum and serde
+* i don't think there's anything interesting to investigate here. marking as triaged.