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stage1: remount entire subcgroup r/w, instead of each knob #3494
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jonboulle
reviewed
Dec 22, 2016
| @@ -332,9 +321,9 @@ func CreateCgroups(m fs.Mounter, root string, enabledCgroups map[int][]string, m | |||
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| // RemountCgroups remounts the v1 cgroup hierarchy under root. | |||
| // It mounts /sys/fs/cgroup/[controller] read-only, | |||
| // but leaves needed knobs in the subcgroup for each app read-write, | |||
| // but leaves needed knobs in the subcgroup the pod read-write, | |||
| // | ||
| // cpuSet should be <stage1rootfs>/sys/fs/cgroup/cpuset | ||
| func fixCpusetKnobs(cpusetPath, subcgroup string) error { | ||
| //cgroupPathFix := filepath.Join(cpusetPath, "system.slice") |
| _ = os.MkdirAll(cgroupPathFix, 0755) | ||
| // Ensure that the hierarchy has consistent cpu restrictions. | ||
| // | ||
| // cpuSet should be <stage1rootfs>/sys/fs/cgroup/cpuset |
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Yeah, I saw that failure. The previous version of the function I refactored ignored errors, but i started paying attention. Of course, it Works On My Machine(tm). |
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@s-urbaniak would you mind making sure my reasoning is correct? This is all a bit moot, since we no longer mount /sys/fs/cgroup in to the stage2, but it still seems prudent. |
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I'm fine with this change, after a rebase and after adding a description of the current status of stage0/stage1/stage2 cgroups in the devdocs (cgroups.md) with a short reference to the backstory (starting from #2351) |
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This mounts the entire subcgroup (machine slice) read-write, instead of mounting only the exact knobs per-app we need.
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@lucab rebased and doc updated, thanks! |
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"TestNetDefaultConnectivity": I think that test has an overly strict output matcher, or alternatively shouldn't be run with |
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ready to go? |
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This remounts the entire subcgroup (machine slice) read-write, instead of only the exact knobs per-app we need.
This is needed for runc (since it wants to manage cgroups for itself). It also simplifies
app add, since we no longer need to manipulate cgroups after pod start time. It also reduces the number of bind mounts to one per controller, making various operations more efficient. (Before, we had one bind mount per controller knob per app).