如何释放MTLBuffer和MTLTexture

Question

我知道如何创建MTLBuffer和/或MTLTexture但是如何在不再需要这些资源时释放GPU内存？

Answer 1

MTLBuffer和MTLTexture是Objective-C对象，因此参考计数。如果您在Objective-C项目中使用自动引用计数或使用Metal通过Swift，只需确保不再保留对缓冲区或纹理的引用，就会释放任何相关的硬件资源。

let texture: MTLTexture? = device.newTexture(with: descriptor)
texture = nil // <- resources will be released

人们可以通过在将nil分配给texture时逐步通过相关组件来证实这一点，[MTLDebugTexture dealloc]首先引导我们到

MetalTools`-[MTLDebugTexture dealloc]:
    ...
->  0x100af569e <+34>: call   0x100af87ee               ; symbol stub for: objc_msgSendSuper2
    0x100af56a3 <+39>: add    rsp, 0x10
    0x100af56a7 <+43>: pop    rbp
    0x100af56a8 <+44>: ret    

[MTLToolsObject dealloc]

......并通过

MetalTools`-[MTLToolsObject dealloc]:
    0x100ac6c7a <+0>:   push   rbp
    0x100ac6c7b <+1>:   mov    rbp, rsp
    0x100ac6c7e <+4>:   push   r14
    ...

GeForceMTLDriver`___lldb_unnamed_symbol1095$$GeForceMTLDriver:
->  0x7fffd2e57b14 <+0>:  push   rbp
    0x7fffd2e57b15 <+1>:  mov    rbp, rsp

......并通过GeForceMTLDriver

dealloc

一直以来，通过各种

id<MTLDevice> m_Device = MTLCreateSystemDefaultDevice();
// allocate Buffer
NSUInteger BufferLength = 100;
id<MTLBuffer> m_Buffer = [m_Device newBufferWithLength:BufferLength options:0]; 

// allocate Texture
MTLTextureDescriptor *shadowTextureDesc = [MTLTextureDescriptor texture2DDescriptorWithPixelFormat: MTLPixelFormatDepth32Float width: 1024 height: 1024 mipmapped: NO];
id<MTLTexture> m_Texture = [m_Device newTextureWithDescriptor:shadowTextureDesc];

// release Buffer
[m_Buffer setPurgeableState:MTLPurgeableStateEmpty]; 
[m_Buffer release];

// release Texture
[m_Texture setPurgeableState:MTLPurgeableStateEmpty];
[m_Texture release];

方法释放任何资源。

Answer 2

如果您使用自动引用计数，正如接受的答案所说，只需设置为nil。

但是如果您使用手动引用计数，Metal有两种动态分配的资源（MTLBuffer && MTLTexture），您可以通过以下方式释放它们。

https://developer.apple.com/documentation/metal/mtlresource/1515898-setpurgeablestate

关于setPurgeableState，你可以参考链接（qazxswpoi）