ShaderX3 6.1 An Extensible Direct3D Resource Management System

1. ShaderX3 6.1 An Extensible Direct3D Resource Management System Shader study 2007.7.25 이동현

2. But Why? • Game and Windows applications can exist together on the desktop. • When some event occurs, all video memory resources owned by the game can be lost. • Lost video memory need to be restored before they can be used again. • Changing from HAL to REF Rasterizer. • What the hell…( if your frame rate counter drops from 60FPS to 60SPF!!!) • But this is not easy, because your 3d device becomes lost.

3. Solution • Disable application and relevant key combos.(Alt-tab…) • It gives a negative felling to end-users. • You must keep track of each and every Direct3D resource you created in your application. • “Notifications” – use virtual functions to deal with all Direct3D resources. • Per-instance basis. So we have to add annoying restoration code for each D3D resource instance. • This is not suitable for large scale applications.

4. But When? • If a d3d app is minimized, or switched to another app using Alt-Tab. • The surfaces that are located in display could be lost. • When changing display modes, display memory surfaces will be lost. • Device lost scenarios. • Full screen display mode -> minimized to different desktop display mode. • A power management event( e.g., sleep or standby) • Device running in windowed mode. Some process causes desktop display mode to change. • Failure of the IDirect3DDevice9::Reset() method. • A mysterious internal driver error. This is rare but happens.

5. But When? • When device is reset( IDirect3DDevice9::Reset()). • Release all resources allocated in D3DPOOL_DEFAULT. • When device is recreted. • All must be released no matter what pool it is placed in.

6. But How? • SXProbe • This will be responsible for “probing” the device to know whether it is lost or not. • SXResource • This is a base class that will be used to wrap Direct3D resources needed to persist device loss and recreation.

7. SXResource Reset device before m_pD3DDevice->Reset Detach Device or Re-Create Device Reset device after m_pD3DDevice->Reset or Created( Re- ) device

8. But Where? “A lost device must recreate resources (including video memory resources) after it has been reset. If a device is lost, the application queries the device to see if it can be restored to the operational state. If not, the application waits until the device can be restored” – [DXSDK02] Attach D3DDevice to SXProbe

9. But Where? • Place our probe • Prior to rendering a scene. • For example, just before IDirect3DDevice9::BeginScene(); • This is usually better, simply because this way the application can avoid rendering at all if the device is lost and cannot be restored at the moment. • Just after calling IDirect3DDevice9::Present. • This works by intercepting the call’s return value, and resetting the device upon failure.

10. But Where?

11. But What? • All video memory must be released before a device can be reset from a lost state to an operational state. • Any swap chains – IDirect3DDevice9::CreateAdditionalSwapChain. • Any resources placed in the D3DPOOL_DEFAULT memory class. • Need not release resources in the D3DPOOL_MANAGED or D3DPOOL_SYSTEMMEM memory classes. • Other state data is automatically destroyed by the transition to an operational state. • For device recreate, every Direct3D resources must be released. • Static vertex buffer -> placed in video memory • Dynamic vertex buffer -> placed in AGP memory.

12. Benefits • Persistent States • In order to guarantee that are always correctly applied to the device no matter if it gets lost/recreated, a class can inherit from SXResource. • Memory Approximation • If the D3DPOOL_DEFAULT resources, check the backup copy. • Rough estimation. • Event-based Device State Information • An application can inject an “information resource” • Ex) When an application wants to suspend its operation upon device loss. • Device Memory Management • The Direct3D API recommends all D3DPOOL_DEFAULT resource first, then following them by D3DPOOL_MANAGED ones.

13. Managing Resources • Base d3d management algorithm is “least-recently-used priority” • In a single frame, switches to a most-recently-used priority.(between BeginScene and EndScene) • D3DPOOL_MANAGED flag • Persist through transitions between the lost and operational states of the device. • The device can be restored with a call to …::Reset() • But if the device must be destroyed and re-created, all resources created using D3DPOOL_MANAGED must be re-created. • D3DPOOL_DEFAULT flag • Not persist through transitions between the lost and operational states of the device. • These resources must be released before calling reset.

14. Resource Management Best Practices D3DSDK Document 참고 하세요

15. Video memory Local video memory Non-local video memory