导入
模型训练的粗略估算
掌握估算生成式AI应用训练和部署所需资源的信封背面计算(back-of-the-envelope)核心方法。
生成式AI系统中的资源估算
一个简单的神经网络
参数数量计算:
Nparams = 2 × 3 + 3 × 1 = 9
隐藏层计算:
H₁ = (X₁ × WX1H1) + (X₂ × WX2H1) + b₁
H₂ = (X₁ × WX1H2) + (X₂ × WX2H2) + b₁
H₃ = (X₁ × WX1H3) + (X₂ × WX2H3) + b₁
输出层计算:
O = (H₁ × WH1O) + (H₂ × WH2O) + (H₃ × WH3O) + b₂
推理时间(秒)计算:
Tsec = 总FLOPS / 每秒FLOPS
总FLOPS计算:
Total FLOPS = Nparams × NFLOPS × E × D
带硬件性能的推理时间:
Tsec = (Nparams × NFLOPS × E × D) / Rops
多GPU情况下的推理时间:
Tsec = (Nparams × NFLOPS × E × D) / (Rops × NGPUs)
考虑通信开销的推理时间:
Tsec = (Nparams × NFLOPS × E × D × C) / (Rops × NGPUs)
重复项(同上):
Tsec = (Nparams × NFLOPS × E × D × C) / (Rops × NGPUs)
推理延迟公式:
Tinference = (Nparams × 2 × C) / Rops