Step 4: Run with Suggestions - 2021.1 English

Vivado Design Suite Tutorial: Design Analysis and Closure Techniques (UG938)

Document ID
UG938
Release Date
2021-07-14
Version
2021.1 English

You will now add a suggestion to a run and examine what happens when a suggestion is applied and how it is reported.

  1. In the Design Runs window, click the + icon and generate both a new Synthesis and Implementation run. Ensure both runs have the Default run strategy and in the final step, select Do not launch now.
  2. In the Design Runs window, right-click on the new synth_2 run and select Set QoR Suggestions ....

  3. Specify the suggestion file as the RQS file added to the project from the previous step and click OK.

  4. Repeat steps 2 and 3 for the implementation run. Specify the same RQS file for each run.
  5. In the Design Runs window, right-click on synth_2 and select Make Active.
  6. In the Flow Navigator, click Run Synthesis.
  7. As this design takes a long time to route, we will only run to place_design and analyze at this stage. When synthesis is complete, in the Design Runs window, right-click on the new implementation run and select Launch Step To > place_design.
  8. With the implementation running, select the Design Runs window and right click → Open Run on the synth_2 synthesis run with QoR Suggestions. When opened select Reports → QoR Suggestions... and select Ok in the dialog box to run the command.
  9. Click on the RQA Summary. You will see that the score has improved from 3 to 4.

  10. Next click on the Assessment Details. You will see that the Net and LUT budget score has been reduced but not eliminated. This is a consequence of the high frequency we are forcing paths to run at in this design:

  11. Close the synthesized design.
  12. When place_design is finished, first go and examine the very top of the implementation log file for the new implementation run. You can see a table summary of the suggestions that have been read in. This summary helps confirm that what is read in is what you expect.
    1. Read QOR Suggestions Summary
    -------------------------------
    
    Read QOR Suggestions Summary
    +---------------------------------------------+---------------+-------+
    |              Suggestion Summary             | Incr Friendly | Total |
    +---------------------------------------------+---------------+-------+
    | Total Number of Suggestions                 |             1 |     5 |
    |   Automatic                                 |             1 |     4 |
    |   Manual                                    |             0 |     1 |
    |   APPLICABLE_AT                             |               |       |
    |    synth_design                             |             0 |     4 |
    |    opt_design                               |             0 |     0 |
    |     That overlap with synthesis suggestions |             0 |     0 |
    |    place_design                             |             1 |     1 |
    |    postplace_phys_opt_design                |             0 |     0 |
    |    route_design                             |             0 |     0 |
    |    postroute_phys_opt_design                |             0 |     0 |
    +---------------------------------------------+---------------+-------+
  13. Right-click on the implementation run and select Open Run Directory. Next open the checkpoint file by double-clicking on top_placed.dcp. This step is necessary as we are examining an intermediate run step in the interests of saving time.
  14. In the new instance of Vivado tools, select Reports > Report QoR Suggestions ... and click OK.
  15. In the new report, you will notice that there are more sections under Suggestion Report.
    • GENERATED - This is where new suggestions are listed
    • EXISTING - These are suggestions that existed previously but are not applied (Not Shown)
    • APPLIED - These are where suggestions that have been applied are listed
    • FAILED TO APPLY - Suggestions where the design objects no longer exist and consequently were not applied (Not shown)

    Also note that the option to add to the project is not available when a checkpoint is opened. You can still export a file but it is not added to a project.

  16. Click APPLIED and select the details table for one of the items. For APPLIED suggestions, the timing path summary is still available but it is not possible to cross probe to other views in Vivado as some items may have changed.