The Small batch (and Other) solutions in Mantle API Guennadi Riguer – Mantle Chief Architect

Small batch performance Problems Abstraction level Small batch performance Platform efficiency

Wrong Abstraction Level Unpredictable big black box Current situation: neither fast nor simple Too high to be fast, too low to be simple

Small Batch Performance 10K 100K Most games today Really optimized games Where you want to be (Mantle target)

Texture atlases & arrays Previous Solutions Geometry instancing Geometry shaders Texture atlases & arrays Uber-shaders Command recorders …

Why They Failed? Development and content creation limitations Trading driver overhead for engine performance Trading CPU performance for GPU overhead

Empower developers to do what they want What is Mantle? Lower level API Focus on performance Empower developers to do what they want

Predictable performance Why Mantle? Better performance Predictable performance Developer control

Key Features

Execution Model GPU Queues Application . . . Graphics Compute DMA App thread

Execution Model GPU Queues Application . . . Graphics Compute DMA App thread

Execution Model GPU Application Queues . . . Graphics Compute DMA App thread Queues

Execution Model Queues Application GPU . . . Graphics Compute DMA App thread Graphics Compute DMA GPU . . .

Memory & Resources Application controls memory Application handles hazards Generalized resources

Pre-build & Pre-validate Pipelines Resource binding Multi-use command buffers

Platform Considerations APUs & SOCs are here No longer CPU vs. GPU Race to low power

Power Efficiency - StarSwarm FPS Power (W) FPS/W The selection of resolutions and settings was made to create both CPU and GPU limited cases for completeness of the produced results. Starswarm using RTS preset @1080p running on APU A10-7800 @ 3.5GHz, 4GB 2133MHz RAM, A88X-Pro M/B

Power Efficiency - Games FPS Power (W) FPS/W The selection of resolutions and settings was made to create both CPU and GPU limited cases for completeness of the produced results. Battlefield 4 BrokenFlightDeck level @720p and @1080p MEDIUM settings and SSAO enabled running on APU A10-7800 @ 3.5GHz, 4GB 2133MHz RAM, A88X-Pro M/B Thief built-in benchmark running on same hardware with low settings at 720x480 and normal settings at 720p

Lessons Learned

Think Outside the Box Don’t just make something faster …avoid doing it completely Design API and driver together

New Driver Design Even a bit of sync kills many-core performance “Thick” driver = cache pollution “Make it the application’s problem” 

The whole is greater than the sum of its parts Lots of Little Things… The whole is greater than the sum of its parts

Future HW Considerations HW small batch, anyone? Command processing bottlenecks More operations/batches in flight

Applications must "do the right thing“ Challenges Programming is harder Ecosystem must change Applications must "do the right thing“

Summary Mantle fixes abstraction level Mantle improves platform efficiency Mantle leads industry transformation

Questions?

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