ci: Improve ccache cache hit rates
#27083
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In Cirrus CI the `/tmp` is a special volume to be mounted into instances running in a Kubernetes cluster, which makes usage of `ccache` cache much less effective.
This change improves cache hit rates for the touched CI tasks.
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Drafted for now as I'm going to demonstrate benefits of this PR by re-running CI twice. First time with cleaned caches, and second one to ensure higher hit rates. |
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Changes that are not affecting binaries, e.g., #27070 or #27072, are expected to show up to 100%
ccachehit rate. But that is not the case:Zero hit rate in the "macOS 10.15" is well known. But a fix was considered not "a good change" and closed.
For another task with nearly-zero hit rate--"ARM64 Android APK"--a fix suggested in #27077.
Here are cache hit rates for other problematic tasks:
In my experiments, making a
ccache_cachefolder task-specific did not help.Apparently, the problem is related to cirruslabs/cirrus-ci-docs#896.
This PR fixes the issue. Also
CCACHE_SIZEvalues have been adjusted for some tasks to avoid cache misses due to "cleanups performed".