大量元素时 Vulkan Buffer WorkGroupID 不返回实际值

Question

使用 pow(2, 24) 和 local_size_x = 64 为布局输入限定符创建缓冲区将 return WorkGroupID = 262143 由于 pow(2,24) / 64 - 1，这一切都很好索引为零。

但是，如果我们将问题的全局维度/无元素/大小增加到 pow(2, 25) 可以说 WorkGroupID 将毫无理由地 return 值，它们与数学不匹配.

这里有一些我认为重要的设备限制：

maxStorageBufferRange:          uint32_t = 4294967295
        maxComputeSharedMemorySize:     uint32_t = 32768
        maxComputeWorkGroupCount:       uint32_t[3] = 00000202898A8EC4
            maxComputeWorkGroupCount[0]:    uint32_t = 65535
            maxComputeWorkGroupCount[1]:    uint32_t = 65535
            maxComputeWorkGroupCount[2]:    uint32_t = 65535
        maxComputeWorkGroupInvocations: uint32_t = 1024
        maxComputeWorkGroupSize:        uint32_t[3] = 00000202898A8ED4
            maxComputeWorkGroupSize[0]:     uint32_t = 1024
            maxComputeWorkGroupSize[1]:     uint32_t = 1024
            maxComputeWorkGroupSize[2]:     uint32_t = 1024

我不会过度分配设备支持的更多元素。所以在 2 天 + 16 小时后我仍然没有弄清楚发生了什么......

WorkGroupSize、WorkGroupID、LocalInvocationID 和 GlobalInvocationID 当我到达 n 号时出现同样的问题。的元素。难怪 GlobalInvocationID 由于其计算方式而出现相同的问题...

#version 450
// Size of the Local Work-group is defined trough input layout qualifier
layout(local_size_x = 64, local_size_y = 1, local_size_z = 1) in;


layout(set = 0, binding = 0) buffer deviceBuffer
{
   uint x[];
};


void main() {
    uint i = gl_GlobalInvocationID.x;
    //uint i = gl_WorkGroupSize.x * gl_WorkGroupID.x * gl_LocalInvocationID.x;


    //x[i] += x[i];

// Total No. of Work Items (threads) in Global Dimension
//x[i] = gl_NumWorkGroups.x;

// Size of Work Dimension specified in Input Layout Qualifier
//x[i] = gl_WorkGroupSize.x;

// Is given by Global Dimension / Work Group Size
x[i] = gl_WorkGroupID.x;

//x[i] = gl_LocalInvocationID.x;

}

Answer 1

maxComputeWorkGroupCount[0]: uint32_t = 65535
maxComputeWorkGroupCount[1]: uint32_t = 65535
maxComputeWorkGroupCount[2]: uint32_t = 65535

vkCmdDispatch have the size in x = pow(2, 25), y = 1, z = 1

根据您提供的信息groupCountX = 2²⁵ = 33554432，但限制是maxComputeWorkGroupCount[0] = 65535 = 2¹⁶-1.

Vulkan 规范 Valid Usage for vkCmdDispatch 说：

groupCountX must be less than or equal to VkPhysicalDeviceLimits::maxComputeWorkGroupCount[0]

违反有效用法是未定义的行为。 "Undefined behavior" 表示从 "everything seemingly working fine" 到 "your PC colapses into a black hole and destroys this solar system" 的任何内容。就所有意图和目的而言，违反有效用法是应用程序代码的逻辑错误。

大量元素时 Vulkan Buffer WorkGroupID 不返回实际值

Vulkan Buffer WorkGroupID not returning actual value when large number of elements

buffer

vulkan

shader-storage-buffer