Hi all. TL;DR: I've created a blueprint [1] regarding weight normalization. I would be very glad if somebody could examine and comment it.
Recently I've been developing some weighers to be used within nova and I found that the weight system was using raw values. This makes difficult for an operator to stablish the importance of a weigher against the rest of them, since the values can range freely and one big magnitude returned by a weigher could shade another one. One solution is to inflate either the multiplier or the weight that is returned by the weigher, but this is an ugly hack (for example, if you increase the RAM on your systems, you will need to adjust the multipliers again). A much better approach is to use weight normalization before actually using the weights With weight normalization a weigher will still return a list of RAW values, but the BaseWeightHandler will normalize all of them into a range of values (0.0 and 1.0) before adding them up. This way, a weight for a given object will be: weight = w1_multiplier * norm(w1) + w2_multiplier * norm(w2) + ... This makes easier to stablish the importance of a weigher regarding the rest, by just adjusting the multiplier. This is explained in [1], and implemented in [2] (with some suggestions by the reviewers). [1] https://blueprints.launchpad.net/openstack/?searchtext=normalize-scheduler-weights [2] https://review.openstack.org/#/c/27160/ Thanks for your feedback, -- Álvaro López García al...@ifca.unican.es _______________________________________________ OpenStack-dev mailing list OpenStack-dev@lists.openstack.org http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
