What's the difference between creating an analysis view and activating it?
From PDVerse MMMC Interview Masterclass, part of the pdVerse Mentor Series
Direct answer
Creating an analysis view [Innovus: create_analysis_view] registers the view definition in the database without evaluating timing. Activating it [Innovus: set_analysis_view -setup {...} -hold {...}] instructs the timing engine to build the timing graph, compute slack, and optimize against that view.
Mentor explanation
Declaration and activation are two distinct steps in MMMC flows.
Key terms
create_analysis_view— defines the pairing of constraint mode and delay corner in the database.set_analysis_view— activates the view for setup, hold, dynamic power, or leakage power analysis and optimization.- Selective activation — defining full signoff views up front (e.g. 50 views) but activating only dominant views during early PnR to save memory and runtime.
A view that is created but not activated is completely ignored by the timing engine and optimizer.
Practical example
Creation vs Activation Commands:
# Step 1: Create 4 views (Defined in DB, but dormant)
create_analysis_view -name v_func_ss -constraint_mode cm_func -delay_corner dc_ss_rcmax
create_analysis_view -name v_func_ff -constraint_mode cm_func -delay_corner dc_ff_rcmin
create_analysis_view -name v_scan_ss -constraint_mode cm_scan -delay_corner dc_ss_rcmax
create_analysis_view -name v_scan_ff -constraint_mode cm_scan -delay_corner dc_ff_rcmin
# Step 2: Actively enable them for timing closure
set_analysis_view \
-setup [list v_func_ss v_scan_ss] \
-hold [list v_func_ff v_scan_ff]Interview trap
Defining views in an MMMC setup script and forgetting the activation command. The tool runs without error but performs zero timing analysis on unactivated views.
Key takeaways
create_analysis_viewdefines the object;set_analysis_viewenables it for timing and optimization.- Only active views are optimized and checked for setup/hold violations.
- Inactive views consume zero CPU during optimization, enabling runtime management.
Self-check: can you answer this aloud?
Try a 45-second answer using this structure:
- State the direct answer.
- Explain the timing or physical reason.
- Name one caveat.
- Say how you would verify it in a real flow.
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