Proposal for placement sort order and score visibility #143
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Signed-off-by: Ben Perry <bhperry94@gmail.com>
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/assign @haoqing0110 @qiujian16 |
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| ## Proposal | ||
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| Add `SortBy` to `PlacementSpec` to configure the sort order for PlacementDecision. This field |
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one of the issue with sorting by score is that if the score changed to frequently, the decision result will be updated frequently also. We need to think about some approach to avoid that, or at least some document to notice users.
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Including that note in the description of SortBy: Score perhaps?
What is the main concern with decision results updating frequently? Including score in the decision results will result in the same number of updates (although not reordering without SortBy). In terms of API pressure, OCM already creates events for each score update. Are there expensive reconcilers that run on update to PlacementDecision?
enhancements/sig-architecture/225-placement-score-visibility/metadata.yaml
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Signed-off-by: Ben Perry <bhperry94@gmail.com>
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/approve |
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[APPROVALNOTIFIER] This PR is APPROVED This pull-request has been approved by: bhperry, qiujian16 The full list of commands accepted by this bot can be found here. The pull request process is described here
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@haoqing0110 @bhperry are we fine to merge this? |
| // SortBy sets the sort order for decisions. | ||
| // It can be "Name", "Score", or "", where "" is "Name" by default. | ||
| // If sortBy is "Name", decisions will be orderd alphanumerically by cluster name | ||
| // If sortBy is "Score", decisions will be ordered numerically in descending order by score, |
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As mentioned above, need to notice user that when sortBy is "Score", the placement decision will trigger an update when score changes. Since today we didn't control the frequency of how user update the AddonPlacmentScore, that means if the score changed too frequently, the decision result will be updated frequently also. Need to set an appropriate score update frequency.
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Defining the time (eg. every 1 minutes) to reschedule the placement might be a way to avoid the pressure on API server, but as the above discussed, the update of the score is uncontrollable, so perhaps the best way for now is just add some notice to the user.
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it might make sense to define a rateLimit, such as MaxUpdatePerMinute
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Enhancement proposal for making PlacementDecision scores easily visible to consumers, and supporting different sort orders in the decisions.