[pypy-dev] pypy 2.2.1 performance on Raspian

[Andy Baker]

OK, thanks - I'm going to try the Raspian CFFI smbus for pypy (already in
the main distro), and if that improves matters, then I'll convert my
libraries from the Cpython 'C' API to CFFI.  Thanks all.

-----Original Message-----
From: Maciej Fijalkowski [mailto:fijall at gmail.com] 
Sent: 02 July 2015 08:22
To: Andy Baker
Cc: Eric Driggers; PyPy Developer Mailing List
Subject: Re: [pypy-dev] pypy 2.2.1 performance on Raspian

for what is worth, you not gonna get better performance from C extensions
between PyPy 2.2 and 2.6

On Wed, Jul 1, 2015 at 6:55 PM, Andy Baker <andy at pistuffing.co.uk> wrote:
> Hi Eric,
>
> You're right - 2.2.1 is long-in-the-tooth but it's the version shipped 
> in the Raspian distribution.  I'll see if I can get the RPIF to 
> upgrade the distro to PyPy 2.6 and I'll give it a go myself too.
>
> Andy
>
> -----Original Message-----
> From: Eric Driggers [mailto:admalledd at gmail.com]
> Sent: 01 July 2015 17:16
> To: Andy Baker
> Cc: PyPy Developer Mailing List
> Subject: Re: [pypy-dev] pypy 2.2.1 performance on Raspian
>
> Unless I am missunderstanding, isn't pypy 2.2.1 rather old? Have you 
> tried a more up-to-date version first? (I seem to see current stable 
> is 2.6.0 and nightly is 2.7.0-alpha0) My memory is that between 2.3 
> and 2.4 there was some armhf work done, and that between 2.3 and 2.5 a 
> whole pile of stuff was done that improved pypy -> C (mostly to help 
> cffi, but helped CAPI and ctypes a bit too IIRC)
>
> It is still probably a good idea to see about using cffi (and you can 
> use cffi on cpython as well!) but low hanging fruit and all that :D
>
> On Wed, Jul 1, 2015 at 8:38 AM, Andy Baker <andy at pistuffing.co.uk> wrote:
>> Hi Armin,
>>
>> Thanks for the insight.  I'll have a look in more detail to port the 'C'
>> modules away from the CPython C API to CFFI.  The performance tests I 
>> was doing were about 10000 loops of reading sensors (the Cpython C 
>> API
>> libraries) along with 1000 loops of arithmatic / trigonometry 
>> processing the sensor data.  I guess the "only 2.5 times slower" is 
>> the balance between the improved math(s) performance and the reduced
> sensor performance.
>>
>> Thanks,
>>
>> Andy
>>
>> -----Original Message-----
>> From: armin.rigo at gmail.com [mailto:armin.rigo at gmail.com] On Behalf Of 
>> Armin Rigo
>> Sent: 01 July 2015 15:33
>> To: Andy Baker
>> Cc: Cory Benfield; PyPy Developer Mailing List
>> Subject: Re: [pypy-dev] pypy 2.2.1 performance on Raspian
>>
>> Hi Andy,
>>
>> Using the CPython C API is very slow on PyPy.  If your program is 
>> mostly spending its time issuing calls via the CPython C API, then 
>> getting
> "only"
>> 2.5x slower is already good :-/  CFFI is much, much faster on PyPy.
>> If you don't want to rewrite your CPython C API modules (even though 
>> you said they are very thin layer, which means it shouldn't be much 
>> work), then you're better off with CPython.
>>
>> Additionally, make sure to read
>> http://pypy.readthedocs.org/en/latest/faq.html#how-fast-is-pypy and 
>> to multiply the time estimates given there by 5 or 10: Raspberry Pi 
>> is much slower than desktop PCs.
>>
>>
>> A bientôt,
>>
>> Armin.
>>
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