[libcxx-commits] [libcxx] [llvm] [libc++][CI] Add a cron job to trigger benchmarking jobs (PR #212859)

[Louis Dionne via libcxx-commits]

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@@ -0,0 +1,138 @@
+# This file defines a workflow that periodically requests benchmark runs for the commits
+# that should have historical performance data but don't yet.
+#
+# The workflow keeps no state: on every invocation, the commits that should be benchmarked
+# are recomputed from Git and the ones that have been benchmarked are recomputed from LNT
+# and from the Github Actions API. It then dispatches libcxx-benchmark-commit.yml for the
+# difference, within a budget. This makes the system converge towards having data for all
+# the desired commits, without necessarily ever reaching that state (as new commits land).
+#
+# The actual configuration driving this job is in libcxx/utils/ci/lnt/machines.json.
+
+name: "[libc++] Request historical benchmark data"
+
+permissions:
+  contents: read
+
+on:
+  schedule:
+    # Trigger every hour, off the hour boundary to avoid popular times.
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ldionne wrote:

According to StackOverflow, that's a "known condition": https://stackoverflow.com/a/78156642 and https://stackoverflow.com/a/67083783

I'm not attached to this, but it seems to make sense that most people would use `0 * * * *` for their hourly crons, meaning everybody runs at the start of the hour.

https://github.com/llvm/llvm-project/pull/212859