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Using GPUView to Understand your DirectX 11 Game Jon Story Developer Relations Engineer, AMD.

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Presentation on theme: "Using GPUView to Understand your DirectX 11 Game Jon Story Developer Relations Engineer, AMD."— Presentation transcript:

1 Using GPUView to Understand your DirectX 11 Game Jon Story Developer Relations Engineer, AMD

2 Agenda ● Windows Display Driver Model (WDDM) ● What is GPUView? ● CPU & GPU Queues ● Threads & Events ● Case Studies ● Summary

3 Windows Display Driver Model (WDDM)

4 Graphics & WDDM Application D3D Runtime Win32 kernel Win32 kernel User Mode Driver (UMD) Kernel Mode Driver (KMD) Dxgkrnl User Mode DWM Process DWM Application Process Session Space Kernel Mode

5 Application #1 D3D Runtime UMD Command Buffer Application #2 Application #2 D3D Runtime UMD Command Buffer User Mode Kernel Mode GPU Scheduler Database Win32k & dxgkrnl KMD DMA Buffer Wait GPU Feeding the GPU…

6 What is GPUView?

7 ● An additional Microsoft performance tool ● Compliments existing tools ● Part of the Windows 7 SDK ● Built on Event Tracing for Windows ● Perfect for monitoring CPU/GPU interaction (even for multiple GPU setups) ● Allows you to see how well the GPU is being fed ● Supports DX9, DX10 & DX11 on Win7

8 Capturing Data ● Run an elevated command prompt ● \Program Files\Microsoft Windows Performance Toolkit\GPUView ● Start your game in windowed mode ● For fullscreen mode perhaps use PsExec from a remote machine ● Start capturing with log.cmd ● Capture seconds of your game ● Stop logging with log.cmd ● Open merged.etl file with GPUView.exe

9 Was this tool created for driver programmers?

10 Navigating the Data ● Use the mouse to select a region ● Ctrl+Z zooms in to a selection ● Z zooms out ● Use +/- to see more or less detail ● Ctrl+E opens the event menu ● Click on objects for additional details ● More on this later…

11 Zooming in…

12 DMA Packet Color Coding ● Various types of DMA packets may be submitted to the GPU: ● Red: Paging packet ● Black: Preemption packet ● Brown: DWM packet ● Other Color: Standard packet ● Other Color + Cross-Hatch: Present packet

13 What does a Standard DMA Packet Represent? ● Graphics system state objects ● Draw commands ● References to resource allocations ● Textures ● Vertex & Index Buffers ● Render Targets ● Constant Buffers

14 CPU & GPU Queues

15 SW Context CPU Queues (1) Desktop Window Manager packet D3D app stacking up 3 frames of packets

16 SW Context CPU Queue (2) CPU queue depth is 6 Task submitted to HW queue CPU queue is empty! New Task submitted to CPU queue

17 SW Context CPU Queues (3) ● Objects represent work submitted to a GPU context ● Queue is represented through time as a stack ● Stack grows on submission of work by the UMD ● Stack shrinks as work is completed by the GPU

18 GPU HW Context Queue (1) Preemption packet DWM Queued DMA Packet Present Packet GPU Processing DMA Packet

19 GPU HW Context Queue (2) GPU starts working on packet GPU finishes working on packet GPU has no work to do

20 GPU HW Context Queue (3) ● Queue is represented through time as a stack ● Stack grows on submission of work by the KMD ● Stack shrinks as work is completed by the GPU ● Gaps indicate a CPU side bottleneck

21 Object Selection Represents latency

22 Object Details (1) Packet type & timing information Allocation references in DMA packet

23 Object Details (2) (w) = Writable by GPU Preferred memory segment P0 = Preferred P1 = Less P2 = Least

24 Object Viewer Segment Numbers: 1 = Vid Mem (CPU visible) 2 = Vid Mem (Non visible) 3 = PCI Express Mem Clearly the depth buffer

25 Paging Buffer Packet ● Submitted as the result of a paging operation (perhaps a large texture) ● Cause is usually resulting from preparing a DMA buffer ● Look at the DMA packet that follows the paging operation

26 Threads & Events

27 HW Threads Colored bars represent idle time Gaps represent work

28 Thread Execution ● Thread segments are colored coded: ● Light blue: Kernel mode ● Dark blue: dxgkrnl ● Red: KMD (Kernel Mode Driver)

29 Charts: FPS / Latency / Memory

30 Viewing Events ● Ctrl+E opens the Event View window ● Can track whatever events take your interest ● DX- Create / Destroy Allocation ● DX Block ● Suggests possible resource contention ● Perhaps trying to lock an in use buffer

31 V-Sync Event

32 Case Studies

33 DrawPredicated SDK Sample GPU is busy, no gaps CPU queue is buffering up nicely App thread not saturated

34 DrawPredicated SDK Sample: + blocking occlusion queries GPU is going idle Not enough being queued up App thread fully saturated

35 Getting Occlusion Queries Right ● Delay picking up results by N frames ● Where N = Number of GPUs ● May need to artificially inflate occlusion volumes to avoid poping

36 What else could cause this problem? ● Locking a Render Target ● Use CopyResource & Staging Textures ● This is a queued operation

37 ContentStreaming SDK Sample (1) Paging packets GPU is going idle

38 ContentStreaming SDK Sample (2) Large resources not getting preferred segments

39 Avoiding Paging ● Keep your video memory usage under control ● Especially in MSAA modes ● Drop texture resolution for lower end HW ● Avoid excessively large amounts of dynamic data ● Textures & Vertex Buffers ● If not sure – talk to us!

40 MultithreadedRendering11 SDK Sample Additional threads preparing packets But there is a lot of D3D runtime / driver overhead

41 Multi-Threaded Rendering and Deferred Contexts ● It is a complex issue ● Don‘t expect it to be a magic bullet ● Strongly recommend you talk to developer relations from AMD & NVIDIA

42 Summary

43 ● Make sure you‘re keeping the ever hungry GPU fed ● Keep track of CPU/GPU interaction ● Keep track of your threads ● Monitor multi-GPU interaction ● Add GPUView to your toolbox

44 Acknowledgments ● Microsoft for creating GPUView ● Microsoft for providing background content

45 Questions?


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