[jax_intro] Update `%time` magic with `%timeit`

[HumphreyYang]

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This PR fixes #206.

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[HumphreyYang]

Hi @jstac,

Since %timeit runs the code multiple times, it's not useful for examples where we want to show the compilation time. So, I only used %timeit on the lines that were causing issues.

Interestingly, f_jit(x) is still slower than f(x), even under %timeit, in the preview here:

%timeit f(x).block_until_ready()
100 ms ± 27 μs per loop (mean ± std. dev. of 7 runs, 10 loops each)

%timeit f_jit(x).block_until_ready()
231 ms ± 313 μs per loop (mean ± std. dev. of 7 runs, 1 loop each)

but I cannot replicate it on Colab. On Colab, the jit version runs much faster:

%timeit f(x).block_until_ready()
127 ms ± 365 µs per loop (mean ± std. dev. of 7 runs, 10 loops each)

%timeit f_jit(x).block_until_ready()
67.4 ms ± 32.1 µs per loop (mean ± std. dev. of 7 runs, 10 loops each)

Colab uses a newer version of JAX (jax==0.5.2), while we are using jax==0.4.35. Nonetheless, I don't think the issue is related to the JAX version, given that it was working properly before.

One approach might be to replace f with a more computationally intensive function so that the jit-compiled version shows a more noticeable performance difference.

Please let me know your thoughts on how we should proceed.

[jstac]

Thanks @HumphreyYang , much appreciated.

@mmcky , do you have thoughts here?

I know you were considering having a separate runner that we control. Overall, it would be nice to control our environment and be a bit more up to date with JAX versions.

[mmcky]

Thanks @HumphreyYang just doing some version checking in https://github.com/QuantEcon/lecture-jax/pull/208 as I'm not sure why the jax version would be that old.

After I get the MIT Solve application together I am going to setup custom GitHub runners. I have done some experiments and we should be able to get the GitHub runner going on the GPU server. It would be ideal to have a dedicated machine though as it will be running arbitrary code from GitHub.

[mmcky]

@HumphreyYang the environment on GitHub actions should be using

jax                       0.5.3                    pypi_0    pypi

can you let me know where you found the old version of jax? Thanks

[HumphreyYang]

Many thanks @mmcky,

I found it under the preview building action:

[HumphreyYang]

Resolved by using JAX==0.6.0