Perf triage, 2020-06-23.

I also updated the triage instructions.

Author: nnethercote

triage/2020.md

@@ -4,6 +4,39 @@ See the [README](README.md) for details on how these logs are collated.
 
 They are in reverse chronological order.
 
+## 2020-06-23
+
+Triage done by njn. Latest revision: 6bb3dbfc6c6d8992d08431f320ba296a0c2f7498.
+Lots of improvements this week!
+
+Having done this for a few weeks now, I see that close to half of the PRs with
+significant performance effects are rollups.
+
+Regressions
+- None.
+
+Improvements
+- [Rollup of 9 pull requests](https://github.com/rust-lang/rust/pull/73563)
+  ([instructions](https://perf.rust-lang.org/compare.html?start=f455e46eae1a227d735091091144601b467e1565&end=7058471adec80a2a1e6092443e08546768c9c894&stat=instructions:u), [max-rss](https://perf.rust-lang.org/compare.html?start=f455e46eae1a227d735091091144601b467e1565&end=7058471adec80a2a1e6092443e08546768c9c894&stat=max-rss)):
+  Up to 33.6% instruction wins on a stress test, and up to 10.3% instructions
+  wins on several real-world benchmarks. Also a max-rss win.
+  [#72788](https://github.com/rust-lang/rust/pull/72788) may be the cause?
+- [Cache flags and escaping vars for predicates](https://github.com/rust-lang/rust/pull/73180)
+  ([instructions](https://perf.rust-lang.org/compare.html?start=a8cf3991177f30694200002cd9479ffbbe6d9a1a&end=1a4e2b6f9c75a0e21722c88a0e3b610d6ffc3ae3&stat=instructions:u)):
+  Up to 4.9% wins across numerous benchmarks.
+- [store `ObligationCause` on the heap](https://github.com/rust-lang/rust/pull/72962)
+  ([instructions](https://perf.rust-lang.org/compare.html?start=f315c35a77e40bd11ce81fedc0556be0f410bbf4&end=c8a9c340de32cb70c8bad8af1a4474f805c5a969&stat=instructions:u)):
+  Up to 3.5% wins across numerous benchmarks.
+- [Upgrade Chalk](https://github.com/rust-lang/rust/pull/72936)
+  ([instructions](https://perf.rust-lang.org/compare.html?start=349f6bfb11d73ebb6a272f9a3d00883484f8218c&end=a8cf3991177f30694200002cd9479ffbbe6d9a1a&stat=instructions:u)):
+  Up to 1.5% wins across numerous benchmarks.
+- [Rollup of 13 pull requests](https://github.com/rust-lang/rust/pull/73511)
+  ([instructions](https://perf.rust-lang.org/compare.html?start=2d8bd9b74dc0cf06d881bac645698ccbcf9d9c5e&end=34c5cd9a64d8537236626c4ccbed39a924cd38e2&stat=instructions:u)):
+  Up to 1.5% wins across numerous benchmarks.
+- [Rollup of 16 pull requests](https://github.com/rust-lang/rust/pull/73528)
+  ([instructions](https://perf.rust-lang.org/compare.html?start=34c5cd9a64d8537236626c4ccbed39a924cd38e2&end=033013cab3a861224fd55f494c8be1cb0349eb49&stat=instructions:u)):
+  Up to 3.4% wins on `wg-grammar`, little change elsewhere.
+
 ## 2020-06-16
 
 Triage done by njn.

triage/README.md

@@ -19,8 +19,14 @@ up on any promised actions. (I.e. nag people!)
 Start a new triage log entry. Follow the format of the preceding entries.
 
 Look through the [`instructions:u` graphs](https://perf.rust-lang.org) for each
-benchmark, looking for significant changes (regressions or improvements) in the
-period since the last triage.
+benchmark.
+- Record the hash of the latest measured revision in the log entry.
+- Set the "start" revision to the previous log entry's latest revision, and the
+  "end" revision to the latest revision. Full SHAs must be used.
+- Uncheck the "Absolute data" checkbox, because that makes changes easier to
+  see.
+
+Look for significant changes (regressions or improvements) in the graphs.
 - Click and drag a region of a graph to zoom in on it. This is useful when data
   points are close together.
 - Click on a data point to open the "compare" page for that merge.
@@ -34,8 +40,10 @@ Easy cases: there is only a single PR in the merge.
   regression, consider requesting a backout. It may be worth looking through
   the comments to see if any perf CI runs were done, and whether the
   regression was expected.
-- Add an entry to the triage log. Include useful details, especially promises
-  of follow-up action from authors.
+- Add an entry to the triage log. Include the PR title, a link to it, and a
+  link to the performance results. Include useful details, such as the size of
+  the regression/improvement, and any promises of follow-up action from authors
+  in the case of a regression.
 
 Difficult cases: the merge was a rollup of multiple PRs.
 - Look through the PRs and try to determine which was the cause. Often you
@@ -47,6 +55,7 @@ Difficult cases: the merge was a rollup of multiple PRs.
   above.
 - You might want to remind the author to use "@bors rollup=never" for PRs
   that are likely to affect performance.
+- Add an entry to the triage log, as for the easy cases.
 
 Repeat with the [`max-rss`
 graphs](https://perf.rust-lang.org/?start=&end=&absolute=true&stat=max-rss).
@@ -60,7 +69,7 @@ Rust](https://github.com/emberian/this-week-in-rust/).
   list of notable merged PRs.
 - Within that subsection, add a list containing a single item.
 - That item should be a link to the triage log entry with the form
-  "YYYY-MM-DD".
+  "YYYY-MM-DD", possibly with some brief text about notable things.
 
 If you have any questions, the #wg-compiler-performance channel on Discord and
 the t-compiler stream on Zulip are good places to ask.