[Python-Dev] Dictionary sparseness (original) (raw)

Jeremy Hylton jeremy@zope.com
05 May 2003 13:11:50 -0400

On Mon, 2003-05-05 at 12:42, Alex Martelli wrote:

On Monday 05 May 2003 05:43 pm, Skip Montanaro wrote: > Jack> I was thinking of something analogous to madvise(): ... > > Quick, everyone who's used madvise() please raise your hand... I'll bet a > beer most people (even on this list) have never put it to good use. We all > know Tim probably has just because he's Tim, and apparently Jack has.

I used madvise extensively (and quite successfully) back when I was the senior software consultant responsible for the lower-levels of a variety of Unix-system ports of a line of mechanical CAD products. And I loved and still love the general concept -- let me advise an optimizer (so it can do whatever -- be it a little or a lot -- rather than spend energy trying to guess what in blazes I may be doing:-).

Have you seen the work on gray-box systems?

http://www.cs.wisc.edu/graybox/

The philosophy of this project seems to be "You can observe an awful lot just by watching." (Apologies to Yogi.) The approach is to learn how a particular service is implemented, e.g. what buffer-replacement algorithm is used, by observing its behavior. Then write an application that exploits that knowledge to drive the system into optimized behavior for the application. No madvise() necessary.

I wonder if the same can be done for dicts? My first guess would be no, because the sparseness is a fixed policy.

Jeremy