Fitter Resource Utilization by Entity Report

The Fitter Resource Utilization by Entity report describes logic utilization in terms of ALMs needed. The Adaptive Logic Module (ALM) is a basic building block that maximizes performance and resource usage in Intel® FPGAs.

Important: The computation of ALMs needed results per hierarchy node displays as a fractional number because the ALM may contain logic belonging to more than one hierarchy. For example, if a particular ALM implements four elements from one hierarchy node and one element from a second node, .80 of an ALM is attributed to the first hierarchy node and the remaining .20 of the ALM is attributed to the second hierarchy node..

ALMs needed—calculated from the result of:

ALMs used in final placement – Estimate of ALMs recoverable by dense packing + Estimate of ALMs unavailable

  • ALMs used in final placement—calculated as the sum of ALM usage as LUT logic and registers, logic only, registers only, and memory.
  • Estimate of ALMs recoverable by dense packing—an estimate of the number ALMs which can be recovered as the design grows. This metric estimates the amount of recoverable logic in units of ALMs. During Place and Route optimization, the Quartus® Prime software permits logic to use more area than is required, improving optimization metrics such as Fmax. However, as the design grows and more logic is added, you may need to know what amount of that space can be recovered.
  • Estimate of ALMs unavailable—an estimate of ALMs that are not used by a specified entity, but are likely not available for usage due to various design and device constraints. The Estimate of ALMs unavailable metric is based on the following factors; ALMs may be unavailable due to location constrained logic, LAB-wide signal conflicts, LAB input limits, or due to virtual I/Os.
    Note: Estimate of ALMs unavailable for a given entity, depends on how the design as a whole is implemented. For example, if the entity is compiled by itself, all of the estimated unavailable logic is attributed to it. If that same entity is compiled with other entities, the estimated unavailable logic will be distributed among all the entities. You should expect to see different estimates of unavailable resources for a given entity depending on how the design is physically implemented.

ALMs used for memory—lists the number of ALMs used to implement memory bits in core logic.

For more information on how the Quartus® Primesoftware calculates logic utilization see the Fitter Resource Usage Summary report in this topic.