Quartus® Prime Standard Edition User Guide: Design Compilation

ID 683283
Date 10/22/2021
Document Table of Contents

1.6.2. Fitter Preservation Level for Design Partitions

The default Fitter Preservation Level for partitions with a Post-Fit netlist type is the highest level of preservation available for the target device family and provides the most compilation time reduction.

You can change the advanced Fitter Preservation Level setting to provide more flexibility in the Fitter during placement and routing. You can set the Fitter Preservation Level on the Advanced tab in the Design Partitions Properties dialog box.

Table 3.  Fitter Preservation Level Settings

Fitter Preservation Level

Quartus® Prime Behavior for Partition During Compilation

Placement and Routing

Preserves the design partition’s netlist atoms and their placement and routing.

This setting reduces compilation times compared to Placement only, but provides less flexibility to the router to make changes if there are changes in other parts of the design.

By default, the Fitter preserves the usage of high-speed programmable power tiles contained within the selected partition, for devices that support high-speed and low-power tiles. You can turn off the Preserve high-speed tiles when preserving placement and routing option on the Advanced tab in the Design Partitions Properties dialog box.


Preserves the netlist atoms and their placement in the design partition. Reroutes the design partition and does not preserve high-speed power tile usage.

Netlist Only

Preserves the netlist atoms of the design partition, but replaces and reroutes the design partition. A post-fit netlist with the atoms preserved can be different than the Post‑Synthesis netlist because it contains Fitter optimizations; for example, Physical Synthesis changes made during a previous Fitting.

You can use this setting to:

  • Preserve Fitter optimizations but allow the software to perform placement and routing again.
  • Reapply certain Fitter optimizations that would otherwise be impossible when the placement is locked down.
  • Resolve resource conflicts between two imported partitions.