Nx performance

[Kyle White]

Hi,

I'm just getting my feet wet with both Elixir and Nx and came across a striking performance difference between Nx and the Stream module for a computation.

My simple example is compute the sum of all odd numbers from 1 to N. Nx is taking ~20x as long as doing the computation without Nx.

Is there some way to optimize this for Nx? any tips? I'm of course looking to do a lot more with Nx but want to be sure I understand how to use it correctly first.

My example code is attached.

Thanks,

Kyle

[Sean Moriarity]

Hi Kyle,

You're running Nx with the default backend (BinaryBackend), which is pure Elixir and very, very slow. You should try EXLA or Torchx as your backend. Try re-running your benchmark, but instead calling `Nx.Defn.global_default_options(compiler: EXLA)` before the call to `Benchmark.add_nx`

Sean

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[Kyle White]

Hi Sean,

Thanks for the quick response on the lame question -- I should have read more of the docs before coming here. ~600ms down to <5 after compilation. Thanks!

Kyle

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[smoria...@gmail.com]

No problem, glad to help, and glad you’re seeing speedups now! 🙂

Sean

On Sep 19, 2022, at 9:19 PM, Kyle White <kylew...@gmail.com> wrote:



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