Re: 90/10 rule... source?

Derek M Jones <derek@knosof.co.uk>
17 Jan 2004 23:27:58 -0500

          From comp.compilers

Related articles
90/10 rule... source? jens.troeger@light-speed.de (Jens Troeger) (2004-01-09)
Re: 90/10 rule... source? derek@knosof.co.uk (Derek M Jones) (2004-01-12)
Re: 90/10 rule... source? nmm1@cus.cam.ac.uk (2004-01-16)
Re: 90/10 rule... source? nkavv@skiathos.physics.auth.gr (2004-01-16)
Re: 90/10 rule... source? gah@ugcs.caltech.edu (glen herrmannsfeldt) (2004-01-17)
Re: 90/10 rule... source? derek@knosof.co.uk (Derek M Jones) (2004-01-17)
Re: 90/10 rule... source? jcownie@etnus.com (James Cownie) (2004-01-22)
Re: 90/10 rule... source? vidar@hokstad.name (2004-01-22)
Re: 90/10 rule... source? ieuk001@attglobal.net (2004-01-22)
Re: 90/10 rule... source? derek@knosof.co.uk (Derek M Jones) (2004-01-31)
| List of all articles for this month |

From: Derek M Jones <derek@knosof.co.uk>
Newsgroups: comp.compilers
Date: 17 Jan 2004 23:27:58 -0500
Organization: Knowledge Software
References: 04-01-038 04-01-059 04-01-077
Keywords: practice, optimize
Posted-Date: 17 Jan 2004 23:27:58 EST

>>> I am looking for a (the) original paper on the 90/10 rule of program
>>> execution. So far I found this reference
>>
>>I think the 90/10 rule might qualify as an urban legend.
>>Example 8 of Knuth's paper quotes a 90% figure, but many of the
>>other examples are around the 50% mark (a few 70%'s).
>
> Yes and no. I think that the rule is real, but it has been made into
> a pseudo law of nature, which it isn't.


What is a pseudo law? One that only applies to a small percentage of
cases?


I think it has more to do with psychology than reality. People tend
to remember those cases where a lot of time was spent in a small
portion of the code. These are cases that are often easier to
optimise (there is a relatively small amount of code to look at);
often resulting in the code not having a 90/10 runtime profile.


>>[I think the 90/10 rule comes from databases, where long before
>>there were computerized files it was well known that in most record
>>systems, a small set of records got most of the lookups. -John]


This sounds like an instance of Zipf's law.


http://linkage.rockefeller.edu/wli/zipf/


Post a followup to this message

Return to the comp.compilers page.
Search the comp.compilers archives again.