[Python-Dev] Caching float(0.0) (original) (raw)

Kristján V. Jónsson kristjan at ccpgames.com
Tue Oct 3 12:15:26 CEST 2006

But that is precisely the point. A non-floating point application tends to use floating point values in a predictable way, with a lot of integral values floating around and lots of zeroes. As this constitutes the majority of python applications (okay, daring assumption here) it seems to warrant some consideration.

In one of my first messages on the subject I promised to report refcounts of -1.0, 0.0 and 1.0 for the EVE server as being. I didn't but instead gave you the frequency of the values reported. Well , now I can provide you with refcounts for the [-10, 10] range plus the total float count, of a server that has just started up:

-10,0 589 -9,0 56 -8,0 65 -7,0 63 -6,0 243 -5,0 731 -4,0 550 -3,0 246 -2,0 246 -1,0 1096 0,0 195446 1,0 79382 2,0 9650 3,0 6224 4,0 5223 5,0 14766 6,0 2616 7,0 1303 8,0 3307 9,0 1447 10,0 8102 total: 331351

The total count of floating point numbers allocated at this point is 985794. Without the reuse, they would be 1317145, so this is a saving of 25%, and of 5Mb.

Kristján

-----Original Message----- From: python-dev-bounces+kristjan=ccpgames.com at python.org [mailto:python-dev-bounces+kristjan=ccpgames.com at python.org] On Behalf Of skip at pobox.com Sent: 3. október 2006 00:54 To: Terry Reedy Cc: python-dev at python.org Subject: Re: [Python-Dev] Caching float(0.0)

Terry> "Kristján V. Jónsson" <kristjan at ccpgames.com> wrote: >> Anyway, Skip noted that 50% of all floats are whole numbers between >> -10 and 10 inclusive, Terry> Please, no. He said something like this about Terry> non-floating-point applications (evidence unspecified, that I Terry> remember). But such applications, by definition, usually don't Terry> have enough floats for caching (or conversion time) to matter too Terry> much. Correct. The non-floating-point application I chose was the one that was most immediately available, "make test". Note that I have no proof that regrtest.py isn't terribly floating point intensive. I just sort of guessed that it was. Skip

More information about the Python-Dev mailing list