Log Analysis and Final Optimizations

Summary

This step completes the analysis of the logs generated in Step 0315, identifies the root cause of the low FPS (6-32 variable FPS), and applies initial optimizations. The analysis revealed that the problem is NOT the rendering (which is very fast: ~3.5ms), but the time between frames which is very variable (30-150ms), causing limited low FPS.

Verification documents were completed with analysis findings and the status of the strategic plan was updated. An initial optimization was applied by disabling the performance monitor to reduce overhead.

Hardware Concept

The Game Boy works at4.194304MHz(4,194,304 cycles per second). A frame lasts approximately70,224 clock cyclesto maintain59.7FPS(typically rounded to 60 FPS on emulators).

An emulator's performance is measured in two key metrics:

• Frame time (render): Time it takes to render a frame. It must be< 16.67ms para 60 FPS.
• Time between frames: Total time between the start of one frame and the start of the next (includes rendering + synchronization). It should be ~16.67ms for 60 FPS.

If the frame time is low but the time between frames is high, the problem is in the main loop (pauses, blocking, or synchronization overhead), not in the rendering.

Fountain:Pan Docs - System Clock, Timing, Frame Rate, LCD Timing

Implementation

FPS Log Analysis

The log was analyzedlogs/perf_step_0312.log(1.5 million lines) using controlled sampling to avoid context saturation:

• Method: WearSelect-Stringwith limits (-First N) to extract samples
• Searched patterns: [PERFORMANCE-TRACE], [FPS-LIMITER], frame times
• Results:
  • Frame time (render):3.23-7.21ms(average ~3.5ms) ✅EXCELLENT
  • FPS (render):138-310FPS(average ~300 FPS) ✅VERY HIGH
  • Time between frames:30-150ms(very variable) ❌PROBLEM
  • FPS (limited):6-32FPS(average ~25 FPS) ❌LOW

Identified Root Cause

The analysis revealed that the problem is NOT the rendering (which is very fast), but thevariable time between framesin the main loop. This suggests:

• Pauses or blocks in the main loop (src/viboy.py, methodrun())
• Synchronization overhead (clock.tick(60))
• Possible logging overhead (although performance monitor only outputs 73 lines out of 1.5M total lines)

Applied Optimization

The performance monitor was disabled in production to reduce overhead:

# src/gpu/renderer.py (line 242)
# Step 0316: DISABLED by default to improve performance
self._performance_trace_enabled = False # DISABLED for Step 0316

This optimization reduces the logging overhead in the rendering loop, although analysis suggests that the main problem is in the main loop, not the rendering.

Completed Documents

• ANALYSIS_FPS_LOW_STEP_0315.md: Complete analysis with findings and recommendations
• VERIFICATION_RENDERIZED_STEP_0312.md: Updated with note from Step 0316
• COMPATIBILITY_GB_GBC_STEP_0315.md: Updated with note from Step 0316
• VERIFICATION_CONTROLES_STEP_0315.md: Updated with note from Step 0316
• STATUS_STRATEGIC_PLAN_STEP_0315.md: Updated with progress from Step 0316

Affected Files

• src/gpu/renderer.py- Disabled performance monitor (line 242)
• ANALYSIS_FPS_LOW_STEP_0315.md- Complete with analysis and findings
• VERIFICATION_RENDERIZED_STEP_0312.md- Updated with Step 0316 note
• COMPATIBILITY_GB_GBC_STEP_0315.md- Updated with Step 0316 note
• VERIFICATION_CONTROLES_STEP_0315.md- Updated with Step 0316 note
• STATUS_STRATEGIC_PLAN_STEP_0315.md- Updated with progress Step 0316

Tests and Verification

The analysis was carried out by analyzing existing logs without running new tests:

• Log analysis:
  • Analyzed log:logs/perf_step_0312.log(1.5 million lines)
  • Method: Controlled samples withSelect-String -First Nto avoid context saturation
  • Extracted patterns: 73 lines[PERFORMANCE-TRACE], frame times, limited FPS
• Validation of findings:
  • Confirmed frame time (render): ~3.5ms (well below the 16.67ms needed for 60 FPS)
  • Confirmed time between frames: 30-150ms (very variable, cause of low FPS)
  • Identified root cause: Variable frame time, NOT rendering issue
• Applied optimization: Performance monitor disabled to reduce overhead

Note: Manual verification by running the emulator is required to confirm that the optimization improves FPS, and additional investigation of the main loop is required to identify the cause of the variable frame time.

Sources consulted

• Bread Docs:System Clock, Timing, Frame Rate, LCD Timing
• Project logs:logs/perf_step_0312.log(performance analysis)

Educational Integrity

Next Steps

• [ ] Manual FPS Check: Run the emulator and check if the optimization improves the FPS
• [ ] Main loop investigation: Reviewsrc/viboy.py(methodrun()) to identify pauses or freezes
• [ ] Main loop optimization: Apply fixes to reduce time between frames
• [ ] Final visual check: Run manually and confirm that the tiles render correctly
• [ ] GB/GBC Compatibility Check: Run manually and document results
• [ ] Verification of controls: Run manually and test each button