Avi Kivity 9559e53f55 Merge 'Adjust tablet-mon.py for capacity-aware load balancing' from Tomasz Grabiec ...

After load-balancer was made capacity-aware it no longer equalizes tablet count per shard, but rather utilization of shard's storage. This makes the old presentation mode not useful in assessing whether balance was reached, since nodes with less capacity will get fewer tablets when in balanced state. This PR adds a new default presentation mode which scales tablet size by its storage utilization so that tablets which have equal shard utilization take equal space on the graph.

To facilitate that, a new virtual table was added: system.load_per_node, which allows the tool to learn about load balancer's view on per-node capacity. It can also serve as a debugging interface to get a view of current balance according to the load-balancer.

Closes scylladb/scylladb#23584

* github.com:scylladb/scylladb:
  tablet-mon.py: Add presentation mode which scales tablet size by its storage utilization
  tablet-mon.py: Center tablet id text properly in the vertical axis
  tablet-mon.py: Show migration stage tag in table mode only when migrating
  virtual-tables: Introduce system.load_per_node
  virtual_tables: memtable_filling_virtual_table: Propagate permit to execute()
  docs: virtual-tables: Fix instructions
  service: tablets: Keep load_stats inside tablet_allocator

2025-04-10 14:59:08 +03:00

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