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2010-04-22
, 11:48
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Posts: 726 |
Thanked: 345 times |
Joined on Apr 2010
@ Sweden
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#12
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Take it into the measurable realm by doing some benchmarking and profiling. When it comes to programming in general, picking the right algorithm that keeps down the complexity gives several magnitudes more effect than trying to micro optimize in lower layers.
When it comes to the Python run-time, check how it's compiled. What optimization is used? How will it affect what Python does the most (whatever that might be)?
What's the aim? 1% faster? 10%? Depending on the goal, different methods might have to be combined. With a properly compiled Python runtime, good choice of algorithms and a reasonable memory footprint that doesn't cause too many cache misses, 1-5% might very well be possible.
And don't forget the Linux environment. What scheduling is used in the kernels delivered by Nokia and the community? Has anyone looked into backporting the new ones, like BrainF u c k scheduling, that's specifically aimed at making the desktop faster? This might make the N900 as a whole faster.
So, lots of variables.
Last edited by Joorin; 2010-04-22 at 11:50. Reason: Silly word filter
When it comes to the Python run-time, check how it's compiled. What optimization is used? How will it affect what Python does the most (whatever that might be)?
What's the aim? 1% faster? 10%? Depending on the goal, different methods might have to be combined. With a properly compiled Python runtime, good choice of algorithms and a reasonable memory footprint that doesn't cause too many cache misses, 1-5% might very well be possible.
And don't forget the Linux environment. What scheduling is used in the kernels delivered by Nokia and the community? Has anyone looked into backporting the new ones, like BrainF u c k scheduling, that's specifically aimed at making the desktop faster? This might make the N900 as a whole faster.
So, lots of variables.
Last edited by Joorin; 2010-04-22 at 11:50. Reason: Silly word filter
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2010-04-22
, 11:51
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Posts: 3,319 |
Thanked: 5,610 times |
Joined on Aug 2008
@ Finland
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#13
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Far from a ready solution, but worth keeping an eye on (smells like Harmattan candidate material):
http://code.google.com/p/unladen-swa...ki/ProjectPlan
http://code.google.com/p/unladen-swa...ki/ProjectPlan
__________________
Blogging about mobile linux - The Penguin Moves!
Maintainer of PyQt (see introduction and docs), AppWatch, QuickBrownFox, etc
Blogging about mobile linux - The Penguin Moves!
Maintainer of PyQt (see introduction and docs), AppWatch, QuickBrownFox, etc
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2010-04-22
, 12:09
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Posts: 138 |
Thanked: 164 times |
Joined on Aug 2009
@ Chateauroux, FRANCE
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#14
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use C++/Qt4 instead of PyQt
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2010-04-22
, 12:22
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Posts: 999 |
Thanked: 1,117 times |
Joined on Dec 2009
@ earth?
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#15
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Originally Posted by TheBootroo
Verrrrrrry funny.
use C++/Qt4 instead of PyQt
That is as helpful as a chocolate matchstick!
__________________
I like cake.
I like cake.
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2010-04-22
, 12:26
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Posts: 999 |
Thanked: 1,117 times |
Joined on Dec 2009
@ earth?
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#16
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What we need are some benchmarks of how things are just now.
See where the bottlenecks are. Then start tweaking things in a controlled manner and compare the bechmarks to the original result.
If we are talking about a specific program then we need to find what routines are the most intensive then maybe re-implement the routine in C/C++ an link it into the Pthon-based program.
Profiling is probably the first step.
Python profiling stuff
Last edited by johnel; 2010-04-22 at 12:34.
See where the bottlenecks are. Then start tweaking things in a controlled manner and compare the bechmarks to the original result.
If we are talking about a specific program then we need to find what routines are the most intensive then maybe re-implement the routine in C/C++ an link it into the Pthon-based program.
Profiling is probably the first step.
Python profiling stuff
__________________
I like cake.
I like cake.
Last edited by johnel; 2010-04-22 at 12:34.
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2010-04-22
, 12:56
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Posts: 1,259 |
Thanked: 1,341 times |
Joined on Oct 2009
@ Germany
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#17
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Okay, not really a speed improvement. But the apple way to do the trick:
http://lists.maemo.org/pipermail/mae...er/021478.html
http://lists.maemo.org/pipermail/mae...er/021478.html
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2010-04-22
, 19:05
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Posts: 1,012 |
Thanked: 817 times |
Joined on Jul 2007
@ France
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#18
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Nouvelle note 47
Please consider that a laucher use memory and in some case can be slower.
Anyway ... there is simple things to optimize python scripts :
- When available, prefer module methode instead of self made in python, as most of module are in c. So really faster
- Avoid when possible too much search in namespace and prefer local method variables it s faster to assign a methode from namespace in a local var when it s called in a loop with more than 10 iterations
- abuse of profile to see where your code is leaking time (available on device)
- abuse of pylint
- instead of doing many test case, use exception : a simple example :
use:
- memorize pattern can help
- avoid cos , sin and tan in a game , use a precalculate array (for vectormine it s optimize fps from 3fps to 60fps)
- and again abuse of profile
- avoid converting data type in loop... Example QString to str
- use existing module when available : PyGtKEditor do all his parsing in python ... it s can be slow on large file, khteditor do the things clearly faster by using some Qt native class.
An other things to doesn't freeze the ui and to not slow down the device by using intensive thread is to divide tasks in very small tasks and to use a sigleton with gidle :
I ve many example to give and there is so man things to say that i ll be able to write a book about py opimization.
So if you need so help optimizing code i can maybe help you.
Last edited by Khertan; 2010-04-26 at 12:30.
Originally Posted by TheBootroo
I'm askin for a ban for a such stupid comment !
use C++/Qt4 instead of PyQt
Please consider that a laucher use memory and in some case can be slower.
Anyway ... there is simple things to optimize python scripts :
- When available, prefer module methode instead of self made in python, as most of module are in c. So really faster
- Avoid when possible too much search in namespace and prefer local method variables it s faster to assign a methode from namespace in a local var when it s called in a loop with more than 10 iterations
- abuse of profile to see where your code is leaking time (available on device)
- abuse of pylint
- instead of doing many test case, use exception : a simple example :
Code:
if (mydiv#0):
res=res/mydiv
else:
res=0
Code:
try:
res=res/mydiv
except NullDivisionError,e:
res=0
- avoid cos , sin and tan in a game , use a precalculate array (for vectormine it s optimize fps from 3fps to 60fps)
- and again abuse of profile
- avoid converting data type in loop... Example QString to str
- use existing module when available : PyGtKEditor do all his parsing in python ... it s can be slow on large file, khteditor do the things clearly faster by using some Qt native class.
An other things to doesn't freeze the ui and to not slow down the device by using intensive thread is to divide tasks in very small tasks and to use a sigleton with gidle :
Code:
import gobject
class _DeferClass(object):
_calls=[]
_ref=None
def __new__(cls,*args,**kw):
if cls._ref is None:
cls._ref = super(_DeferClass,cls).__new__(cls,*args,
**kw)
return cls._ref
def __len__(self):
return len(self._calls)
def __call__(self,func,*args):
def NextCall():
(func,args)=self._calls[0]
func(*args)
self._calls=self._calls[1:]
return self._calls!=[]
if not self._calls: gobject.idle_add(NextCall)
self._calls.append((func,args))
So if you need so help optimizing code i can maybe help you.
__________________
Benoît HERVIER, Khertan
KhtEditor - Sdist_Maemo - Khweeteur - PyPackager - KhtSimpleText - KhtNotes - KhtBMA - Wleux - and more ...
Benoît HERVIER, Khertan
KhtEditor - Sdist_Maemo - Khweeteur - PyPackager - KhtSimpleText - KhtNotes - KhtBMA - Wleux - and more ...
Last edited by Khertan; 2010-04-26 at 12:30.
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2010-04-22
, 19:15
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Posts: 1,366 |
Thanked: 1,185 times |
Joined on Jan 2006
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#19
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Khertan you are Sweenie Todd 
I'm eating Py, that s**t is so advanced I dont even know what it does
I'm eating Py, that s**t is so advanced I dont even know what it does
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N900_Email_Options Wiki Page
N900_Email_Options Wiki Page
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2010-04-22
, 19:19
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Posts: 1,684 |
Thanked: 1,562 times |
Joined on Jun 2008
@ Austin, TX
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#20
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Originally Posted by lcuk
I can't say off of a benchmark but comments affect parsing. If pyc (or even better?) pyo files are already generated, stored, and run then comments shouldn't matter.
does removing the comments make a noticable difference to script runtime?
GCDialer (old name for Dialcentral) use to remove extra whitespace and merge multiple python files into one. I didn't feel the cost/benefit was worth it but didn't benchmark it.
I did do some benchmarking and found that class assignments are slow. When creating a lot of class variables (like pre-compiling a bunch of regexes) it was faster to create them on the instance. I normally have only one instance so no extra copies to worry about.
For general python optimizations there is already a decent guide
http://wiki.python.org/moin/PythonSpeed/PerformanceTips
Originally Posted by attila77
Benchmarks are so-so for now but they haven't gotten a chance yet to do the optimizations they wanted. The real killer is this is very memory intensive which the acceptance into CPython is conditioned on improving memory usage. Start time is also an issue for now.
Far from a ready solution, but worth keeping an eye on (smells like Harmattan candidate material):
http://code.google.com/p/unladen-swa...ki/ProjectPlan
http://www.python.org/dev/peps/pep-3146/
Long term, PyPy is the project I'm more excited about. They've recently added support for CPython extension modules which was a major blocker for transitioning. Speed is a mixed bag. I'm unsure about start time or memory usage though.
http://speed.pypy.org/overview/
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TheOneRing, DialCentral, Gonvert, Quicknote, Multilist, ejpi, nQa, Waters of Shiloah
Programming Blog
770, n810, n900, Ideapad S10-3t
TheOneRing, DialCentral, Gonvert, Quicknote, Multilist, ejpi, nQa, Waters of Shiloah
Programming Blog
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