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John Owens
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Oct 24, 2024
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"use strict"; | ||
const { create, globals } = require("../../src/dawn-build/dawn.node"); | ||
Object.assign(globalThis, globals); // Provides constants like GPUBufferUsage.MAP_READ | ||
let navigator = { gpu: create([]) }; | ||
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// begin TimingHelper code | ||
function assert(cond, msg = "") { | ||
if (!cond) { | ||
throw new Error(msg); | ||
} | ||
} | ||
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class TimingHelper { | ||
#canTimestamp; | ||
#device; | ||
#querySet; | ||
#resolveBuffer; | ||
#resultBuffer; | ||
#resultBuffers = []; | ||
// state can be 'free', 'need resolve', 'wait for result' | ||
#state = "free"; | ||
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constructor(device) { | ||
this.#device = device; | ||
this.#canTimestamp = device.features.has("timestamp-query"); | ||
if (this.#canTimestamp) { | ||
this.#querySet = device.createQuerySet({ | ||
type: "timestamp", | ||
count: 2, | ||
}); | ||
this.#resolveBuffer = device.createBuffer({ | ||
size: this.#querySet.count * 8, | ||
usage: GPUBufferUsage.QUERY_RESOLVE | GPUBufferUsage.COPY_SRC, | ||
}); | ||
} | ||
} | ||
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#beginTimestampPass(encoder, fnName, descriptor) { | ||
if (this.#canTimestamp) { | ||
assert(this.#state === "free", "state not free"); | ||
this.#state = "need resolve"; | ||
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const pass = encoder[fnName]({ | ||
...descriptor, | ||
...{ | ||
timestampWrites: { | ||
querySet: this.#querySet, | ||
beginningOfPassWriteIndex: 0, | ||
endOfPassWriteIndex: 1, | ||
}, | ||
}, | ||
}); | ||
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const resolve = () => this.#resolveTiming(encoder); | ||
pass.end = (function (origFn) { | ||
return function () { | ||
origFn.call(this); | ||
resolve(); | ||
}; | ||
})(pass.end); | ||
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return pass; | ||
} else { | ||
return encoder[fnName](descriptor); | ||
} | ||
} | ||
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beginRenderPass(encoder, descriptor = {}) { | ||
return this.#beginTimestampPass(encoder, "beginRenderPass", descriptor); | ||
} | ||
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beginComputePass(encoder, descriptor = {}) { | ||
return this.#beginTimestampPass(encoder, "beginComputePass", descriptor); | ||
} | ||
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#resolveTiming(encoder) { | ||
if (!this.#canTimestamp) { | ||
return; | ||
} | ||
assert(this.#state === "need resolve", "must call addTimestampToPass"); | ||
this.#state = "wait for result"; | ||
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this.#resultBuffer = | ||
this.#resultBuffers.pop() || | ||
this.#device.createBuffer({ | ||
size: this.#resolveBuffer.size, | ||
usage: GPUBufferUsage.COPY_DST | GPUBufferUsage.MAP_READ, | ||
}); | ||
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encoder.resolveQuerySet( | ||
this.#querySet, | ||
0, | ||
this.#querySet.count, | ||
this.#resolveBuffer, | ||
0 | ||
); | ||
encoder.copyBufferToBuffer( | ||
this.#resolveBuffer, | ||
0, | ||
this.#resultBuffer, | ||
0, | ||
this.#resultBuffer.size | ||
); | ||
} | ||
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async getResult() { | ||
if (!this.#canTimestamp) { | ||
return 0; | ||
} | ||
assert(this.#state === "wait for result", "must call resolveTiming"); | ||
this.#state = "free"; | ||
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const resultBuffer = this.#resultBuffer; | ||
await resultBuffer.mapAsync(GPUMapMode.READ); | ||
const times = new BigInt64Array(resultBuffer.getMappedRange()); | ||
console.log( | ||
"Returned timestamps in result buffer:", | ||
Number(times[1]), | ||
Number(times[0]) | ||
); | ||
const duration = Number(times[1] - times[0]); | ||
resultBuffer.unmap(); | ||
this.#resultBuffers.push(resultBuffer); | ||
return duration; | ||
} | ||
} | ||
// end TimingHelper code | ||
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async function main() { | ||
const adapter = await navigator.gpu?.requestAdapter(); | ||
const canTimestamp = adapter.features.has("timestamp-query"); | ||
const device = await adapter?.requestDevice({ | ||
requiredFeatures: [...(canTimestamp ? ["timestamp-query"] : [])], | ||
}); | ||
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if (!device) { | ||
fail("Fatal error: Device does not support WebGPU."); | ||
} | ||
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if (!canTimestamp) { | ||
fail( | ||
'Fatal error: Device does not support WebGPU timestamp query (`adapter.features.has("timestamp-query")` is false).' | ||
); | ||
} | ||
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const workgroupSize = 64; | ||
const memsrcSize = 2 ** 24; | ||
const timingHelper = new TimingHelper(device); | ||
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const workgroupCount = memsrcSize / workgroupSize; | ||
const dispatchGeometry = [workgroupCount, 1]; | ||
while ( | ||
dispatchGeometry[0] > adapter.limits.maxComputeWorkgroupsPerDimension | ||
) { | ||
dispatchGeometry[0] /= 2; | ||
dispatchGeometry[1] *= 2; | ||
} | ||
console.log(`workgroup count: ${workgroupCount} | ||
workgroup size: ${workgroupSize} | ||
maxComputeWGPerDim: ${adapter.limits.maxComputeWorkgroupsPerDimension} | ||
dispatchGeometry: ${dispatchGeometry}`); | ||
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const memsrc = new Uint32Array(memsrcSize); | ||
for (let i = 0; i < memsrc.length; i++) { | ||
memsrc[i] = i; | ||
} | ||
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const memcpyModule = device.createShaderModule({ | ||
label: "copy large chunk of memory from memSrc to memDest", | ||
code: /* wgsl */ ` | ||
/* output */ | ||
@group(0) @binding(0) var<storage, read_write> memDest: array<u32>; | ||
/* input */ | ||
@group(0) @binding(1) var<storage, read> memSrc: array<u32>; | ||
@compute @workgroup_size(${workgroupSize}) fn memcpyKernel( | ||
@builtin(global_invocation_id) id: vec3u, | ||
@builtin(num_workgroups) nwg: vec3u, | ||
@builtin(workgroup_id) wgid: vec3u) { | ||
let i = id.y * nwg.x * ${workgroupSize} + id.x; | ||
memDest[i] = memSrc[i] + 1; | ||
} | ||
`, | ||
}); | ||
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const memcpyPipeline = device.createComputePipeline({ | ||
label: "memcpy compute pipeline", | ||
layout: "auto", | ||
compute: { | ||
module: memcpyModule, | ||
}, | ||
}); | ||
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// create buffers on the GPU to hold data | ||
// read-only inputs: | ||
const memsrcBuffer = device.createBuffer({ | ||
label: "memory source buffer", | ||
size: memsrc.byteLength, | ||
usage: GPUBufferUsage.STORAGE | GPUBufferUsage.COPY_DST, | ||
}); | ||
device.queue.writeBuffer(memsrcBuffer, 0, memsrc); | ||
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const memdestBuffer = device.createBuffer({ | ||
label: "memory destination buffer", | ||
size: memsrc.byteLength, | ||
usage: GPUBufferUsage.STORAGE | GPUBufferUsage.COPY_SRC, | ||
}); | ||
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const mappableMemdstBuffer = device.createBuffer({ | ||
label: "mappable memory destination buffer", | ||
size: memsrc.byteLength, | ||
usage: GPUBufferUsage.MAP_READ | GPUBufferUsage.COPY_DST, | ||
}); | ||
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/** Set up bindGroups per compute kernel to tell the shader which buffers to use */ | ||
const memcpyBindGroup = device.createBindGroup({ | ||
label: "bindGroup for memcpy kernel", | ||
layout: memcpyPipeline.getBindGroupLayout(0), | ||
entries: [ | ||
{ binding: 0, resource: { buffer: memdestBuffer } }, | ||
{ binding: 1, resource: { buffer: memsrcBuffer } }, | ||
], | ||
}); | ||
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const encoder = device.createCommandEncoder({ | ||
label: "memcpy encoder", | ||
}); | ||
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const memcpyPass = timingHelper.beginComputePass(encoder, { | ||
label: "memcpy compute pass", | ||
}); | ||
memcpyPass.setPipeline(memcpyPipeline); | ||
memcpyPass.setBindGroup(0, memcpyBindGroup); | ||
// TODO handle not evenly divisible by wgSize | ||
memcpyPass.dispatchWorkgroups(...dispatchGeometry); | ||
memcpyPass.end(); | ||
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// Encode a command to copy the results to a mappable buffer. | ||
// this is (from, to) | ||
encoder.copyBufferToBuffer( | ||
memdestBuffer, | ||
0, | ||
mappableMemdstBuffer, | ||
0, | ||
mappableMemdstBuffer.size | ||
); | ||
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// Finish encoding and submit the commands | ||
const command_buffer = encoder.finish(); | ||
device.queue.submit([command_buffer]); | ||
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// Read the results | ||
await mappableMemdstBuffer.mapAsync(GPUMapMode.READ); | ||
const memdest = new Uint32Array( | ||
mappableMemdstBuffer.getMappedRange().slice() | ||
); | ||
mappableMemdstBuffer.unmap(); | ||
let errors = 0; | ||
for (let i = 0; i < memdest.length; i++) { | ||
if (memsrc[i] + 1 != memdest[i]) { | ||
if (errors < 5) { | ||
console.log( | ||
`Error ${errors}: i=${i}, src=${memsrc[i]}, dest=${memdest[i]}` | ||
); | ||
} | ||
errors++; | ||
} | ||
} | ||
if (errors > 0) { | ||
console.log(`Memdest size: ${memdest.length} | Errors: ${errors}`); | ||
} else { | ||
console.log(`Memdest size: ${memdest.length} | No errors!`); | ||
} | ||
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timingHelper.getResult().then((ns) => { | ||
let bytesTransferred = 2 * memdest.byteLength; | ||
console.log( | ||
`Timing result: ${ns} ns; transferred ${bytesTransferred} bytes; bandwidth = ${ | ||
bytesTransferred / ns | ||
} GB/s` | ||
); | ||
}); | ||
} | ||
main(); | ||
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function fail(msg) { | ||
// eslint-disable-next-line no-alert | ||
alert(msg); | ||
} |