Add triage for this week

This also adjusts the weekly_report script to avoid generating results for
changes that are only in the coercions println benchmark; it is quite noisy.

triage/2021-04-13.md

@@ -0,0 +1,30 @@
+# 2021-04-13 Triage Log
+
+A very quiet week overall.
+
+Triage done by **@simulacrum**.
+Revision range: [d32238532138485c80db4f2cd596372bce214e00..5258a74c887f8ae14717e1f98b652b470877ce4e](https://perf.rust-lang.org/?start=d32238532138485c80db4f2cd596372bce214e00&end=5258a74c887f8ae14717e1f98b652b470877ce4e&absolute=false&stat=instructions%3Au)
+
+1 Regressions, 0 Improvements, 0 Mixed
+??? of them in rollups
+
+#### Regressions
+
+Update stdarch submodule (to before it switched to const generics) [#83776](https://github.com/rust-lang/rust/issues/83776)
+- Large regression in [instruction counts](https://perf.rust-lang.org/compare.html?start=1284da34da56a17ae368e4673920ec4120562cbd&end=d0695c9081b16077d0aed368bccaf437d77ff497&stat=instructions:u) (up to 6.3% on `incr-unchanged` builds of `deeply-nested-closures-debug`)
+- Mostly a regression for doc benchmarks, but also a 1.5% regression in memory
+  usage on check, debug, and opt builds across all benchmarks.
+
+#### Improvements
+
+- None
+
+#### Mixed
+
+- None
+
+#### Nags requiring follow up
+
+- The [issue](https://github.com/rust-lang/rust/pull/82964#issuecomment-800663588) from three weeks ago has stalled.
+  Likely this needs someone to mentor the author, or to take over the
+  investigation.

triage/weekly_report.py

@@ -61,7 +61,7 @@ def eprint(*args, **kwargs):
 
 
 def get_username():
-    usernames = {'mackendy': 'ecstaticmorse', 'joshua': 'jyn514'}
+    usernames = {'mackendy': 'ecstaticmorse', 'joshua': 'jyn514', 'mark': 'simulacrum'}
 
     home_dir = Path.home().name
 
@@ -123,7 +123,12 @@ def relative_change(self):
         return relative_change(*self.results)
 
     def is_significant(self):
-        return abs(self.log_change()) > self.__class__.SIGNIFICANCE_THRESHOLD
+        if self.bench_name.startswith("coercions-debug") and self.cache_state == "incr-patched: println":
+            # This particular (benchmark, cache) combination frequently varies
+            # by up to 2% up and down.
+            return abs(self.relative_change()) > 2
+        else:
+            return abs(self.log_change()) > self.__class__.SIGNIFICANCE_THRESHOLD
 
     def is_increase(self):
         return self.results[1] > self.results[0]