[Python-Dev] Caching float(0.0)

Nick Craig-Wood nick at craig-wood.com
Tue Oct 3 10:14:41 CEST 2006

On Tue, Oct 03, 2006 at 09:47:03AM +1000, Delaney, Timothy (Tim) wrote:
> This doesn't actually give us a very useful indication of potential
> memory savings. What I think would be more useful is tracking the
> maximum simultaneous count of each value i.e. what the maximum refcount
> would have been if they were shared.

It isn't just memory savings we are playing for.

Even if 0.0 is allocated and de-allocated 10,000 times in a row, there
would be no memory savings by caching its value.

However there would be
a) less allocator overhead - allocation objects is relatively expensive
b) better caching of the value
c) less cache thrashing

I think you'll find that even in the no memory saving case a few
cycles spent on comparison with 0.0 (or maybe a few other values) will
speed up programs.

Nick Craig-Wood <nick at craig-wood.com> -- http://www.craig-wood.com/nick

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