filled in 2023-09-05 report.

Author: pnkfelix

triage/2023-09-05.md

@@ -1,8 +1,10 @@
 # 2023-09-05 Triage Log
 
-TODO: Summary
+A lot of spurious noise this week from a few benchmarks (bitmaps-3.1.0, libc,
+and even cargo-0.60.0 at a few points). Beyond that, we had a few small
+improvements associated with the trait system and with parallel-rustc.
 
-Triage done by **@???**.
+Triage done by **@pnkfelix**.
 Revision range: [cedbe5c7..15e52b05](https://perf.rust-lang.org/?start=cedbe5c715c1fa9359683c5f108bed2054ac258b&end=15e52b05ca8f63e0da27c808680388717e5b997e&absolute=false&stat=instructions%3Au)
 
 **Summary**:
@@ -16,7 +18,7 @@ Revision range: [cedbe5c7..15e52b05](https://perf.rust-lang.org/?start=cedbe5c71
 | All ❌✅ (primary)                 | -1.5% | [-10.2%, 1.2%]  | 80    |
 
 
-4 Regressions, 7 Improvements, 8 Mixed; ??? of them in rollups
+4 Regressions, 7 Improvements, 8 Mixed; 2 of them in rollups
 66 artifact comparisons made in total
 
 #### Regressions
@@ -31,6 +33,7 @@ Adapt table sizes to the contents, accommodating u64 rmeta offsets [#113542](htt
 | Improvements ✅ <br /> (secondary) | -    | -            | 0     |
 | All ❌✅ (primary)                 | 0.5% | [0.2%, 1.2%] | 11    |
 
+* already marked as triaged.
 
 Use conditional synchronization for Lock [#111713](https://github.com/rust-lang/rust/pull/111713) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=7659abc63d33223fa366c8781c81698e28a21e6c&end=61efe9d2981b87ec7f2800d62f98c594de151713&stat=instructions:u)
 
@@ -42,6 +45,8 @@ Use conditional synchronization for Lock [#111713](https://github.com/rust-lang/
 | Improvements ✅ <br /> (secondary) | -    | -            | 0     |
 | All ❌✅ (primary)                 | 2.3% | [2.3%, 2.3%] | 1     |
 
+* the measured regression appears spurious
+* marked as triaged
 
 update Miri [#115496](https://github.com/rust-lang/rust/pull/115496) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=7cc5ac267f536ee2cf2f38961d9db8304a419d5a&end=b89d7d6882532686fd90a89cec1a0fd386f0ade3&stat=instructions:u)
 
@@ -53,6 +58,8 @@ update Miri [#115496](https://github.com/rust-lang/rust/pull/115496) [(Compariso
 | Improvements ✅ <br /> (secondary) | -    | -            | 0     |
 | All ❌✅ (primary)                 | 0.3% | [0.2%, 0.4%] | 4     |
 
+* believe to be spurious, marking as triaged
+
 
 Rollup of 5 pull requests [#115553](https://github.com/rust-lang/rust/pull/115553) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=626a6ab93fafd01b37b1e26c96cb6eec0d39f3eb&end=8cfaf70c320297dd1831a12351fcfeab7a231328&stat=instructions:u)
 
@@ -64,6 +71,7 @@ Rollup of 5 pull requests [#115553](https://github.com/rust-lang/rust/pull/11555
 | Improvements ✅ <br /> (secondary) | -    | -            | 0     |
 | All ❌✅ (primary)                 | 0.7% | [0.7%, 0.8%] | 6     |
 
+* believe to be spurious, marking as triaged
 
 #### Improvements
 
@@ -77,6 +85,7 @@ Don't record spans for predicates in coherence [#115392](https://github.com/rust
 | Improvements ✅ <br /> (secondary) | -0.8% | [-1.0%, -0.2%] | 8     |
 | All ❌✅ (primary)                 | -1.1% | [-2.5%, -0.3%] | 18    |
 
+* undoes regression introduced by [PR 115392](https://github.com/rust-lang/rust/pull/115392)
 
 Use `OnceLock` for `SingleCache` [#115422](https://github.com/rust-lang/rust/pull/115422) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=f9ba43ce147707fb90d038983789d8e57451eb6d&end=9dc11a13fa848c1b09b7248c540528190dcb79c5&stat=instructions:u)
 
@@ -132,6 +141,7 @@ Move RawOsError defination to sys [#115493](https://github.com/rust-lang/rust/pu
 | Improvements ✅ <br /> (secondary) | -     | -              | 0     |
 | All ❌✅ (primary)                 | -0.6% | [-0.6%, -0.6%] | 3     |
 
+* (I suspect this is spurious)
 
 read_via_copy: don't prematurely optimize away the read [#115531](https://github.com/rust-lang/rust/pull/115531) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=9c609ae158aab27f1e7df446de6f2c09414012a9&end=626a6ab93fafd01b37b1e26c96cb6eec0d39f3eb&stat=instructions:u)
 
@@ -143,6 +153,7 @@ read_via_copy: don't prematurely optimize away the read [#115531](https://github
 | Improvements ✅ <br /> (secondary) | -     | -              | 0     |
 | All ❌✅ (primary)                 | -0.7% | [-0.7%, -0.7%] | 5     |
 
+* (I suspect this is spurious)
 
 #### Mixed
 
@@ -156,6 +167,8 @@ interpret: fix projecting into an unsized field of a local [#114483](https://git
 | Improvements ✅ <br /> (secondary) | -0.4% | [-0.4%, -0.4%] | 3     |
 | All ❌✅ (primary)                 | -2.2% | [-2.2%, -2.2%] | 1     |
 
+* Ralf notes: "Regressions only affect our ctfe stress test, so it's likely some exaggerated consequence of a tiny change."
+* marked as triaged
 
 Lower `Or` pattern without allocating place [#111752](https://github.com/rust-lang/rust/pull/111752) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=d6b4d35d5e94f6a1577e0e645fb23afc84615a6c&end=f4555ef5e14e8f0630fc5ad4e8efaef56d4acd4b&stat=instructions:u)
 
@@ -167,6 +180,8 @@ Lower `Or` pattern without allocating place [#111752](https://github.com/rust-la
 | Improvements ✅ <br /> (secondary) | -0.4% | [-0.5%, -0.3%] | 3     |
 | All ❌✅ (primary)                 | -0.3% | [-3.7%, 1.0%]  | 18    |
 
+* nnethercote notes: "Performance-wise, icounts/cycles/wall-times have a mix of wins and losses that more or less balance out. But binary size has lots of wins, which is nice."
+* marked as triaged
 
 Skip rendering metadata strings from include_str!/include_bytes! [#115286](https://github.com/rust-lang/rust/pull/115286) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=9dc11a13fa848c1b09b7248c540528190dcb79c5&end=1fb6947abc68683db05f837f07531a2f7d7ed8b3&stat=instructions:u)
 
@@ -178,6 +193,8 @@ Skip rendering metadata strings from include_str!/include_bytes! [#115286](https
 | Improvements ✅ <br /> (secondary) | -2.6% | [-3.7%, -1.7%]  | 9     |
 | All ❌✅ (primary)                 | -2.8% | [-10.3%, 0.3%]  | 29    |
 
+* saethlin notes: "Regressions look like recovery from a spurious improvement in the previous run, and are way less significant than the improvements."
+* already marked as triaged
 
 bootstrap: use git merge-base for LLVM CI download logic [#115409](https://github.com/rust-lang/rust/pull/115409) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=ad8f601ca2ba6186de6e1b2b5f46f47e18013961&end=585bb5e68d85c1e4f32da3e2499343372626a436&stat=instructions:u)
 
@@ -190,6 +207,10 @@ bootstrap: use git merge-base for LLVM CI download logic [#115409](https://githu
 | All ❌✅ (primary)                 | 0.8%  | [-0.4%, 1.5%]  | 8     |
 
 
+* this is a collection of spurious regressions to bitmaps-3.1.0
+    * see e.g. [this graph](https://perf.rust-lang.org/index.html?start=2023-08-31&end=2023-09-05&benchmark=bitmaps-3.1.0&profile=check&scenario=full&stat=instructions%3Au&kind=raw) and note the blip.
+* marked as triaged
+
 Add note on non-exhaustiveness when matching on str and nested non-exhaustive enums [#115270](https://github.com/rust-lang/rust/pull/115270) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=2a1af898b2cb535a45cefe67acf9d023eff16b27&end=21305f4d5f32bcbc97f3b8e66dc23b03f3d948c4&stat=instructions:u)
 
 | (instructions:u)                   | mean  | range          | count |
@@ -200,6 +221,8 @@ Add note on non-exhaustiveness when matching on str and nested non-exhaustive en
 | Improvements ✅ <br /> (secondary) | -0.5% | [-0.5%, -0.5%] | 1     |
 | All ❌✅ (primary)                 | 1.1%  | [0.8%, 1.4%]   | 6     |
 
+* seems like continued spurious noise on bitmaps-3.1.0
+* marked as triaged
 
 Rollup of 5 pull requests [#115518](https://github.com/rust-lang/rust/pull/115518) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=21305f4d5f32bcbc97f3b8e66dc23b03f3d948c4&end=58e967a9cc3bd39122e8cb728e8cec6e3a4eeef2&stat=instructions:u)
 
@@ -211,6 +234,8 @@ Rollup of 5 pull requests [#115518](https://github.com/rust-lang/rust/pull/11551
 | Improvements ✅ <br /> (secondary) | -     | -              | 0     |
 | All ❌✅ (primary)                 | 0.8%  | [-1.5%, 13.6%] | 9     |
 
+* 13.6% regression to cargo-0.60.0 seems spurious (!), since it immediately returned to normal in #115491
+* marked as triaged
 
 Outline panicking code for `RefCell::borrow` and `RefCell::borrow_mut` [#115491](https://github.com/rust-lang/rust/pull/115491) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=58e967a9cc3bd39122e8cb728e8cec6e3a4eeef2&end=abfc6c44381fb033c6b3b0a6bfb804a799f39afd&stat=instructions:u)
 
@@ -222,6 +247,8 @@ Outline panicking code for `RefCell::borrow` and `RefCell::borrow_mut` [#115491]
 | Improvements ✅ <br /> (secondary) | -0.5% | [-0.6%, -0.5%]  | 4     |
 | All ❌✅ (primary)                 | -0.4% | [-12.0%, 1.5%]  | 10    |
 
+* as lqd notes: "bitmaps and cargo opt incr-unchanged kinda look noisy atm"
+* marked as triaged
 
 Do not require associated types with Self: Sized to uphold bounds when confirming object candidate [#115467](https://github.com/rust-lang/rust/pull/115467) [(Comparison Link)](https://perf.rust-lang.org/compare.html?start=04374cd74264b9d3b7d2d3df08ae38df8af4d020&end=9c609ae158aab27f1e7df446de6f2c09414012a9&stat=instructions:u)
 
@@ -233,41 +260,5 @@ Do not require associated types with Self: Sized to uphold bounds when confirmin
 | Improvements ✅ <br /> (secondary) | -     | -              | 0     |
 | All ❌✅ (primary)                 | -0.6% | [-1.2%, 0.6%]  | 7     |
 
-
-#### Untriaged Pull Requests
-
-- [#115553 Rollup of 5 pull requests](https://github.com/rust-lang/rust/pull/115553)
-- [#115518 Rollup of 5 pull requests](https://github.com/rust-lang/rust/pull/115518)
-- [#115496 update Miri](https://github.com/rust-lang/rust/pull/115496)
-- [#115491 Outline panicking code for `RefCell::borrow` and `RefCell::borrow_mut`](https://github.com/rust-lang/rust/pull/115491)
-- [#115467 Do not require associated types with Self: Sized to uphold bounds when confirming object candidate](https://github.com/rust-lang/rust/pull/115467)
-- [#115409 bootstrap: use git merge-base for LLVM CI download logic](https://github.com/rust-lang/rust/pull/115409)
-- [#115270 Add note on non-exhaustiveness when matching on str and nested non-exhaustive enums](https://github.com/rust-lang/rust/pull/115270)
-- [#115082 Fix races conditions with `SyntaxContext` decoding](https://github.com/rust-lang/rust/pull/115082)
-- [#114892 Remove conditional use of `Sharded` from query caches](https://github.com/rust-lang/rust/pull/114892)
-- [#114483 interpret: fix projecting into an unsized field of a local](https://github.com/rust-lang/rust/pull/114483)
-- [#114481 Rollup of 9 pull requests](https://github.com/rust-lang/rust/pull/114481)
-- [#114459 Do not run ConstProp on mir_for_ctfe.](https://github.com/rust-lang/rust/pull/114459)
-- [#114321 get auto traits for parallel rustc](https://github.com/rust-lang/rust/pull/114321)
-- [#114023 Warn on inductive cycle in coherence leading to impls being considered not overlapping](https://github.com/rust-lang/rust/pull/114023)
-- [#114004 Add `riscv64gc-unknown-hermit` target](https://github.com/rust-lang/rust/pull/114004)
-- [#113858 Always const-prop scalars and scalar pairs](https://github.com/rust-lang/rust/pull/113858)
-- [#113758 Turn copy into moves during DSE.](https://github.com/rust-lang/rust/pull/113758)
-- [#113485 Bump version to 1.73](https://github.com/rust-lang/rust/pull/113485)
-- [#113370 Rollup of 8 pull requests](https://github.com/rust-lang/rust/pull/113370)
-- [#113320 Add some extra information to opaque type cycle errors](https://github.com/rust-lang/rust/pull/113320)
-- [#113306 Update debuginfo test runner to provide more useful output](https://github.com/rust-lang/rust/pull/113306)
-- [#113304 Upgrade to indexmap 2.0.0](https://github.com/rust-lang/rust/pull/113304)
-- [#113270 perform TokenStream replacement in-place when possible in expand_macro](https://github.com/rust-lang/rust/pull/113270)
-- [#113057 Rollup of 2 pull requests](https://github.com/rust-lang/rust/pull/113057)
-- [#112963 Stop bubbling out hidden types from the eval obligation queries](https://github.com/rust-lang/rust/pull/112963)
-- [#112882 Rewrite `UnDerefer`](https://github.com/rust-lang/rust/pull/112882)
-- [#112420 Rollup of 4 pull requests](https://github.com/rust-lang/rust/pull/112420)
-- [#112157 Resurrect: rustc_target: Add alignment to indirectly-passed by-value types, correcting the alignment of byval on x86 in the process.](https://github.com/rust-lang/rust/pull/112157)
-- [#112083 Make `TrustedStep` require `Copy`](https://github.com/rust-lang/rust/pull/112083)
-- [#112016 Rollup of 6 pull requests](https://github.com/rust-lang/rust/pull/112016)
-
-#### Nags requiring follow up
-
-TODO: Nags
-
+* all these changes (for better or for worse) look like yet more spurious noise.
+* marked as triaged