Fabric cu allocation

Hi jwryu 
Thanks for using Fabric Community.
Autoscale allows capacity administrators to automatically trigger individual Power BI v-cores whenever the capacity usage reaches the purchased capacity limits. With the latest updates on the capacity usage rules, we now allow capacity usage to consume future CPU. Autoscale is a valuable mechanism to prevent capacity usage exceeding 100% and to add usage into the carry forward to be paid off in a future window.

You are right. If resource needs fluctuate, enable autoscale for your FSKU to automatically adjust capacity within limits. 
For more information please refer to this link:
https://debruyn.dev/2023/a-closer-look-at-microsoft-fabric-pricing-billing-and-autoscaling/
Hope this helps. Please let me know if you have any further questions.

Hi jwryu 
Unfortunately, there's no fixed ratio or priority for CU allocation in Microsoft Fabric when multiple artifacts (notebooks, pipelines, Dataflow Gen2, and Power BI) run concurrently. But you can use the Microsoft Fabric Capacity Metrics App.

The Microsoft Fabric Capacity Metrics app is designed to provide monitoring capabilities for Microsoft Fabric capacities. Monitoring your capacities is essential for making informed decisions on how to best use your capacity resources. For example, the app can help identify when to scale up your capacity or when to turn on autoscale.

For more information please refer to this documents:
https://learn.microsoft.com/en-us/fabric/enterprise/metrics-app
https://learn.microsoft.com/en-us/fabric/enterprise/metrics-app-install?tabs=1st
https://learn.microsoft.com/en-us/fabric/enterprise/metrics-app-compute-page

Hope this helps. Please let me know if you have any further questions.