[SciPy-Dev] GSoC proposal draft: Improve performance through the use of Pythran

[Xingyu Liu]

Thanks for providing information about the array copy issue! I didn't notice that before ... I think optimizing this would be very useful, I can help test it if you implement it later :)

Thanks,
Xingyu

On 2021/4/9, 4:23 AM, "SciPy-Dev on behalf of Serge Guelton" <scipy-dev-bounces+xingyuliu=g.harvard.edu at python.org on behalf of serge.guelton at telecom-bretagne.eu> wrote:

    On Thu, Apr 08, 2021 at 06:56:17PM +0200, David Menéndez Hurtado wrote:
    > It is unfortunate that the example you choose turned up to be slower than pure
    > Python. If you could figure out what turns out to be slowing it down, maybe
    > pythran could fix it. But I realise this may take quite some time, so it may
    > have to wait until the project starts.

    Xingyu Liu opened an issue in the pythran tracker about that performance issue[1]
    I've started investigating, and his problem exhibits an interesting situation,
    where bascially whe have

    ```
    if a < b:
      x[b:] = x[:a]
    ```

    when doing an array copy like this, numpy semantic prevents usage of a memcpy,
    because they may overlap. However in that case, the guard contains information
    to allow the memcpy. This is an optimization that could be implemented at Python
    level, but that would require an extension of the range analysis of pythran, as
    it doesn't work on symbolic value. Probably not within the scope of a GSoc
    though ;-)



    [1] https://github.com/serge-sans-paille/pythran/issues/1753
    > /David 
    > 
    > On Thu, 8 Apr 2021, 5:10 pm Xingyu Liu, <[1]xingyuliu at g.harvard.edu> wrote:
    > 
    > 
    >     Hi everyone:
    > 
    >      
    > 
    >     I'm Xingyu Liu(@charlotte12l on GitHub), a first-year Data Science master
    >     student at Harvard University, and I’m proficient in Python and C++. I’m
    >     very interested in the project - Improve performance through the use of
    >     Pythran. I did many investigations and tries on this project these days 
    >     (many thanks to Ralf for helping me iterating this proposal!), and here is
    >     my current proposal draft: [2]https://docs.google.com/document/d/
    >     1nM7dYbmModiukQw-sSOVGz6t5S6HC0VVWucYadI_aMQ/edit?usp=sharing .
    > 
    >      
    > 
    >     I’d appreciate it if you guys can give me some tips on it!
    > 
    >      
    > 
    >     Thanks,
    > 
    >     Xingyu
    > 
    >      
    > 
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    > 
    > 
    > References:
    > 
    > [1] mailto:xingyuliu at g.harvard.edu
    > [2] https://docs.google.com/document/d/1nM7dYbmModiukQw-sSOVGz6t5S6HC0VVWucYadI_aMQ/edit?usp=sharing
    > [3] mailto:SciPy-Dev at python.org
    > [4] https://mail.python.org/mailman/listinfo/scipy-dev

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