kvserver: increase rebalance action impact req #98889
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Previously, the store rebalancer would attempt to transfer leases or relocate replicas of a range so long as the load of the range (estimated using the local leaseholder replica) was greater than 0.1% of the store's load. This commit updates the value to be higher for both lease rebalancing and range rebalancing, specifically: lease rebalancing: 0.1% -> 0.5% range rebalancing: 0.1% -> 2.0% The documented rationale, as for why these values exist is also the reason for the increase: decrease unnecessary churn. Only the hottest ranges are considered, when the impact of a rebalance action for these ranges is estimated to be less than a small fraction of the store's total load, it is indicative that the distribution of replica load is not skewed. Letting the replicate queue balance replica and lease counts is a better option in such distributions. Making the minimum for range rebalancing higher is also added, as multiple replicas for a range is inherently more costly than moving a lease. Resolves: cockroachdb#98890 Release note: None
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Reviewable status:
complete! 1 of 0 LGTMs obtained (waiting on @kvoli)
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Won't backport. I agree, it's generally a risky change and we don't have a pressing need. |
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In light of #104292 I'm going to merge this now and see how we do. |
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bors r=andrewbaptist |
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Build failed: |
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bors r=andrewbaptist |
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Build succeeded: |
Previously, the store rebalancer would attempt to transfer leases or relocate replicas of a range so long as the load of the range (estimated using the local leaseholder replica) was greater than 0.1% of the store's load.
This commit updates the value to be higher for both lease rebalancing and range rebalancing, specifically:
lease rebalancing: 0.1% -> 0.5%
range rebalancing: 0.1% -> 2.0%
The documented rationale, as for why these values exist is also the reason for the increase: decrease unnecessary churn. Only the hottest ranges are considered, when the impact of a rebalance action for these ranges is estimated to be less than a small fraction of the store's total load, it is indicative that the distribution of replica load is not skewed. Letting the replicate queue balance replica and lease counts is a better option in such distributions (until we consolidate rebalancing responsibility).
Making the minimum for range rebalancing higher is also added, as multiple replicas for a range is inherently more costly than moving a lease.
Resolves: #98890
Release note: None