Re: [RFC PATCH-SERIES cluster/ha-manager/manager/proxmox 0/7] clamp load imbalance to unit interval

["Daniel Kral" <d.kral@proxmox.com>]

On Mon Apr 27, 2026 at 3:20 PM CEST, Dominik Rusovac wrote:
> # TL;DR 
> clamp load imbalance to value between 0 and 1, and display the value as
> percentage in HA Status panel of PVE UI. 
>
> # Details
> The currently used load imbalance value is given as the so-called coefficient of
> variation (CV), a value that may exceed 1. As such, the CV value alone lacks
> meaning. A CV value of 0.0 means no imbalance, but what does a value of, say,
> 1.7 mean?
>
> Relative to the number of nodes in a cluster, it is possible to determine the
> upper bound of the CV value [0][1]. By dividing the CV value by its upper
> bound, the load imbalance can be represented as a value that varies between 0
> and 1. Expressing the CV as a percentage makes the concept of load imbalance
> easier to interpret.
>
> # Summary of Changes
> This series:
> - represents load imbalance as a value between 0 and 1;
> - adds a maximum value of 1.0 for load scheduler options; and
> - integrates the load imbalance value within the HA status endpoint; 
>   this is to provide feedback on the prevailing load imbalance in the PVE UI.

As discussed off-list, it would be interesting to also keep a history of
the imbalance value for the cluster.

In that discussion we also wondered whether we could derive that history
without changing the rrdcached schema at all by fetching the
average/maximum values for the already pre-defined time frames (each
minute, each hour, etc.) and use the same calculate_node_imbalance(),
but just for the raw values.

Haven't checked how much error this does introduce since the rrdcached
values are different from the sampled values fetched from the rrddump in
the HA Manager simply because these are averaged out, but it would be
interesting if the introduced error is negible enough.