Add comprehensive analysis of ZScream vs YAZE overworld implementations
- Introduced a detailed comparison document highlighting the functional equivalence between ZScream (C#) and YAZE (C++) overworld loading logic. - Verified key areas such as tile loading, expansion detection, map decompression, and coordinate calculations, confirming consistent behavior across both implementations. - Documented differences and improvements in YAZE, including enhanced error handling and memory management. - Provided validation results from integration tests ensuring data integrity and compatibility with existing ROMs.
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docs/analysis/dungeon_parallel_optimization_summary.md
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docs/analysis/dungeon_parallel_optimization_summary.md
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# DungeonEditor Parallel Optimization Implementation
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## 🚀 **Parallelization Strategy Implemented**
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### **Problem Identified**
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- **DungeonEditor::LoadAllRooms**: **17,966ms (17.97 seconds)** - 99.9% of loading time
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- Loading **296 rooms** sequentially, each involving complex operations
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- Perfect candidate for parallelization due to independent room processing
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### **Solution: Multi-Threaded Room Loading**
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#### **Key Optimizations**
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1. **Parallel Room Processing**
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```cpp
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// Load 296 rooms using up to 8 threads
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const int max_concurrency = std::min(8, std::thread::hardware_concurrency());
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const int rooms_per_thread = (296 + max_concurrency - 1) / max_concurrency;
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```
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2. **Thread-Safe Result Collection**
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```cpp
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std::mutex results_mutex;
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std::vector<std::pair<int, zelda3::RoomSize>> room_size_results;
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std::vector<std::pair<int, ImVec4>> room_palette_results;
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```
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3. **Optimized Thread Distribution**
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- **8 threads maximum** (reasonable limit for room loading)
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- **~37 rooms per thread** (296 ÷ 8 = 37 rooms per thread)
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- **Hardware concurrency aware** (adapts to available CPU cores)
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#### **Parallel Processing Flow**
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```cpp
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// Each thread processes a batch of rooms
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for (int i = start_room; i < end_room; ++i) {
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// 1. Load room data (expensive operation)
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rooms[i] = zelda3::LoadRoomFromRom(rom_, i);
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// 2. Calculate room size
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auto room_size = zelda3::CalculateRoomSize(rom_, i);
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// 3. Load room objects
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rooms[i].LoadObjects();
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// 4. Process palette (thread-safe collection)
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// ... palette processing ...
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}
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```
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#### **Thread Safety Features**
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1. **Mutex Protection**: `std::mutex results_mutex` protects shared data structures
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2. **Lock Guards**: `std::lock_guard<std::mutex>` ensures thread-safe result collection
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3. **Independent Processing**: Each thread works on different room ranges
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4. **Synchronized Results**: Results collected and sorted on main thread
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### **Expected Performance Impact**
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#### **Theoretical Speedup**
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- **8x faster** with 8 threads (ideal case)
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- **Realistic expectation**: **4-6x speedup** due to:
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- Thread creation overhead
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- Mutex contention
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- Memory bandwidth limitations
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- Cache coherency issues
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#### **Expected Results**
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- **Before**: 17,966ms (17.97 seconds)
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- **After**: **2,000-4,500ms (2-4.5 seconds)**
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- **Total Loading Time**: **2.5-5 seconds** (down from 18.6 seconds)
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- **Overall Improvement**: **70-85% reduction** in loading time
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### **Technical Implementation Details**
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#### **Thread Management**
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```cpp
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std::vector<std::future<absl::Status>> futures;
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for (int thread_id = 0; thread_id < max_concurrency; ++thread_id) {
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auto task = [this, &rooms, thread_id, rooms_per_thread, ...]() -> absl::Status {
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// Process room batch
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return absl::OkStatus();
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};
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futures.emplace_back(std::async(std::launch::async, task));
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}
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// Wait for all threads to complete
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for (auto& future : futures) {
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RETURN_IF_ERROR(future.get());
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}
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```
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#### **Result Processing**
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```cpp
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// Sort results by room ID for consistent ordering
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std::sort(room_size_results.begin(), room_size_results.end(),
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[](const auto& a, const auto& b) { return a.first < b.first; });
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// Process collected results on main thread
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for (const auto& [room_id, room_size] : room_size_results) {
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room_size_pointers_.push_back(room_size.room_size_pointer);
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// ... process results ...
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}
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```
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### **Monitoring and Validation**
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#### **Performance Timing Added**
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- **DungeonRoomLoader::PostProcessResults**: Measures result processing time
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- **Thread creation overhead**: Minimal compared to room loading time
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- **Result collection time**: Expected to be <100ms
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#### **Logging and Debugging**
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```cpp
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util::logf("Loading %d dungeon rooms using %d threads (%d rooms per thread)",
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kTotalRooms, max_concurrency, rooms_per_thread);
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```
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### **Benefits of This Approach**
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1. **Massive Performance Gain**: 70-85% reduction in loading time
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2. **Scalable**: Automatically adapts to available CPU cores
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3. **Thread-Safe**: Proper synchronization prevents data corruption
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4. **Maintainable**: Clean separation of parallel processing and result collection
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5. **Robust**: Error handling per thread with proper status propagation
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### **Next Steps**
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1. **Test Performance**: Run application and measure actual speedup
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2. **Validate Results**: Ensure room data integrity is maintained
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3. **Fine-tune**: Adjust thread count if needed based on results
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4. **Monitor**: Watch for any threading issues or performance regressions
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This parallel optimization should transform YAZE from a slow-loading application to a lightning-fast ROM editor!
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