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The `resources.cpu` field is scheduled in MHz. On most Linux task drivers, this value is then mapped to a `cpu.share` (cgroups v1) or `cpu.weight` (cgroups v2). But this means on very large hosts where the total compute is greater than the Linux kernel defined maximum CPU shares, you can't set a `resources.cpu` value large enough to consume the entire host. The `cpu.share`/`cpu.weight` value is relative within the parent cgroup's slice, which is owned by Nomad. So we can fix this by re-normalizing the weight on very large hosts such that the maximum `resources.cpu` matches up with largest possible CPU share. This happens in the task driver so that the rest of Nomad doesn't need to be aware of this implementation detail. Note that these functions will result in bad share config if the request is more than the available, but that's supposed to be caught in the scheduler so by not catching it here we intentionally hit the runc error. Fixes: https://hashicorp.atlassian.net/browse/NMD-297 Fixes: https://github.com/hashicorp/nomad/issues/7731 Ref: https://go.hashi.co/rfc/nmd-211