Dagger memory usage #862
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Dagger memory usage #862
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When reconfiguring the system many times (seen during regression testing), the RAM usage of keeping all generations around starts to add up. A tmpfs file, no matter how small, will always consume at least one full page (4k). So one generation of tiny setup scripts and log files can end up locking a 1 MB (!) of memory. Therefore: Once we're done with a generation, archive it in a compressed tarball, which typically fits inside a single 4k page. Limit the total number of archives to 10. This should give full visibility into the history of a system in all normal situations, while still allowing hammering systems with reconfig cycles in testing scenarios.
Previously, the generation number was only increased for successful evolutions. This led to a confusing state in /run/net where multiple <N>-ABANDONED-<date> directories could exist, with the same value of N. Move to a scheme where the generation increments every time we evolve, even if the evolution fails. If multiple consecutive evolutions fail, we can now unabiguously determine the order in which they were executed.
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Description
When reconfiguring the system many times (seen during regression testing), the RAM usage of keeping all generations around starts to add up.
A tmpfs file, no matter how small, will always consume at least one full page (4k). So one generation of tiny setup scripts and log files can end up locking⚠️ 1 MB ⚠️ of memory.
Therefore: Once we're done with a generation, archive it in a compressed tarball, which typically fits inside a single 4k page. Limit the total number of archives to 10. This should give full visibility into the history of a system in all normal situations, while still allowing hammering systems with reconfig cycles in testing scenarios.
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