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AR# 24185

11.1 Incremental Design/Partition/Project Navigator - When should I use partitions?


Keywords: do, don't, do not

When should I use partitions?


Use Partitions

Use partitions when:
- You want 100% preservation on a hierarchical block.
- You want to lock down a hierarchical block in the design.
- Your design has major functional blocks that are broken up by natural design hierarchy (e.g., large designs, team-based designs, EDK designs, DSP designs).
- Your design has "whack-a-mole" timing problems.
- You want to receive resource utilization statistics per hierarchical block.
- You cannot use SmartGuide (e.g., it uses too much memory; you do not want map-timing; you are making design changes that result in major changes in synthesis results).
- You want to use Partial Reconfig or Team Design (future).
- You want to improve implementation runtime (and turns per day). Note that SmartGuide also improves implementation runtimes.
- You want to improve synthesis runtimes (and turns per day). Note that SmartGuide does not improve synthesis runtimes.
- You are making "large" changes to the design. If the design is highly utilized, this might require backing off preservation levels of unchanged partitions.
- You want a finer level of control over preservation. Note that SmartGuide is either on or off and applies to the whole design. Partitions support per-partition preservation control of synthesis, placement, or routing.

Do Not Use Partitions

Do not use partitions when:
- You want global optimization across all hierarchical blocks.
- Your flat design is not meeting timing and you do not have hierarchical blocks that can be partitioned without further damaging the timing.
- Your flat design has high slice utilization.
- You have "ifdefs" in your source code.
- You have VHDL Libraries.
- You have "include" files in a local directory or explicit path.
- Your synthesis tool comes from Mentor.
- Your synthesis tool is basic Synplify (without support for compile points).
- Your TBUF is crossing Partitions.
- You have I/O DDR, I/O, or I/O Register is a lower-level module.
- Your synthesis tool in ISE is Simplicity; must use standalone.
- You cannot do bottom up synthesis flow.
- You cannot use on Generate Statement instances for HDL designs.
- You cannot use on cores; must place them on a wrapper.
- You cannot use the EDK flow; must use a wrapper.
- Your critical path is between partitioned modules.
- Your timing margins are very small.
- You have active low control signals in Virtex-5 devices.
- If hierarchical blocks are in the same file and change one block, all the partitions are reimplemented.

If you cannot use partitions, use SmartGuide to reduce runtime and improve efficiency.
AR# 24185
Date 06/25/2009
Status Active
Type General Article
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