c++ - Not all invocations running

Question

I am attempting to implement a simple compute operation of multiplying all values in a buffer by a push constant.

This shader:

#version 450
layout(local_size_x = 1024, local_size_y = 1, local_size_z = 1) in;

layout(binding = 0) buffer Buffer { float x[]; };
layout(push_constant) uniform PushConsts { float a; };

void main() {
    x[gl_GlobalInvocationID.x] *= a;
}

In my current implementation from my prints I get:

in:
1 2 3 4 5 5 4 3 2 1
[7]

workgroups: (1,1,1)

out:
7 14 3 4 5 5 4 3 2 1

• 1 2 3 4 5 5 4 3 2 1 being the initial values of the buffer.
• 7 being the value of the push constant.
• (1,1,1) being the number of workgroups set.
• 7 14 3 4 5 5 4 3 2 1 being the resultant values of the buffer after execution.

Strangely only the 1st 2 values have been multiplied by the push constant (which leads me to think only the 1st 2 invocations ran). I suspect this is likely an issue with memory allocation, although I don’t know where it may be coming from.

I would greatly appreciate any help, and if there is anything I can do to make this post better please let me know.

Project link, code file link and the .spv files (.comp files are in the repo, but I thought it worth including these in case you didn't want to compile the .comp files)

Answer 1

Problem originated with setting the size of the VkBuffer and VkDescriptorBufferInfo to the number of values rather than the number of bytes.

Making these changes fixes it:

• bufferCreateInfo.size = size; -> bufferCreateInfo.size = sizeof(float)*size;
• bindings[i].range = size; -> bindings[i].range = VK_WHOLE_SIZE;