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units: let systemd user/capsule manage its own CPU/I/O pressure handling - #44395

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bluca:user_io_pressure
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systemd:mainfrom
bluca:user_io_pressure

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@bluca

@bluca bluca commented Oct 23, 2026

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With I/O accounting enabled, inherited pressure parameters prevent the user manager from setting its own threshold, producing:

systemd[807]: Failed to adjust io pressure threshold, ignoring: Device or resource busy

Use IOPressureWatch=skip, as for memory pressure, so the user manager configures monitoring for its own init.scope.

Follow-up for 9d03637

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github-actions Bot commented Oct 23, 2026 •

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Reviewed da3d977 (architecture, correctness, lifetimes, security, style, tests). All findings are resolved 🎉

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  • units/user@​.service.in:38 CPU pressure has the same issue: with CPUWeight=/CPUQuota= set on user@​.service (cpu is delegated), cgroup_context_want_pressure() returns true for auto, $CPU_PRESSURE_WATCH is inherited, and setting the period fails with EBUSY. Add CPUPressureWatch=skip too.
  • units/user@​.service.in:38 units/capsule@​.service.in also runs systemd --user with DelegateSubgroup=init.scope and only MemoryPressureWatch=skip, so with IO accounting on a capsule manager hits the same EBUSY. Add IOPressureWatch=skip there as well.

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@github-actions github-actions Bot added units please-review PR is ready for (re-)review by a maintainer labels Oct 23, 2026
Comment thread units/user@.service.in
Comment thread units/user@.service.in
With CPU/I/O accounting enabled, inherited pressure parameters prevent the
user manager from setting its own threshold, producing:

systemd[807]: Failed to adjust io pressure threshold, ignoring: Device or resource busy

Use CPU/IOPressureWatch=skip, as for memory pressure, so the user manager
and capsule manager configure monitoring for their own init.scope.

Follow-up for 9d03637
@bluca bluca changed the title units: let systemd --user manage its own I/O pressure handling units: let systemd user/capsule manage its own CPU/I/O pressure handling Oct 24, 2026

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