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fix(cloud): discount shrinkable ZFS ARC from host memory used - #102
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The ARC lives outside the page cache, so MemAvailable counts it as used and ZFS hosts (Proxmox, TrueNAS) can trip the host-pressure memory alert on cache alone. Subtract size - c_min from arcstats, like htop/btop.
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What
Host memory used is
MemTotal - MemAvailable. The ZFS ARC lives outside the Linux page cache, so the kernel counts it as used even though ZFS gives it back under pressure. On ZFS hosts (Proxmox, TrueNAS), the cache alone can push a host over the host-pressure memory threshold.This subtracts the shrinkable part of the ARC (
size - c_minfrom/proc/spl/kstat/zfs/arcstats, the same figure htop/btop use). Hosts without ZFS are unchanged.Tests
Added
cloud/hostmetrics_test.go, which covers meminfo without ZFS, the ARC discount, and an ARC at its floor.🤖 Generated with Claude Code