Oprofile, swap

[Benjamin M. Schwartz]

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Ivan Krstić wrote:
> On Dec 18, 2007, at 12:27 PM, Jameson Chema Quinn wrote:
>> Has anyone looked at Psyco on the XO?
> 
> 
> Psyco improves performance at the cost of memory. On a memory- 
> constrained machine, it's a tradeoff that can only be made in laser- 
> focused, specific cases. We have not done the work -- partly for lack  
> of time, partly for lack of sufficiently good tools -- to determine  
> those foci.

Indeed.

OLPC's requirements for a Python compiler or JIT are way beyond
state-of-the-art.  It will take at least a few more years for PyPy to be useful
for OLPC.  Also:

1. Many performance problems are due to design (e.g. UI waiting on IO).

2. Many computational bottlenecks will be fixable in pure Python by choosing a
faster algorithm or implementation.

3. In cases where the fastest version in Python is still not fast enough, Psyco
is not likely to be the best solution.  See http://scipy.org/PerformancePython ,
where Psyco is 30% faster than Python, but 400 times slower than Pyrex, C, or C++.

- --Ben
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