Space-time tradeoffs (was: Re: radical suggestion for fc4 release)

Eric S. Raymond esr at
Tue Feb 1 05:30:53 UTC 2005

Jeff Johnson <n3npq at>:
> Is memory a bigger problem than cpu? How about broadband vs. dialup?
> I have no clue where the balance points are. My rpm job is objective 
> measurements through insturmentation, and as reliable and stable an 
> implementation as possible.
> Go make up your own answers.

OK, here is an answer.  

We don't know exactly what the "right" tradeoff between space efficiency
and decompression time is.  But we *do* know which direction that tradeoff
is heading.  

Processor clocks are getting cheaper faster than memory is.  Memory is getting
cheaper faster than disk is.  Disk is getting cheaper a *lot* faster than
bits-per-second of bandwidth.

The "right" tradeoff is to use lots of cheap resources in order to be 
able to use fewer expensive resources.  Therefore, as these trends 
continue, we want to spend processor clocks to decrease use of bandwidth.

Thus, bzip2 wins over gzip.
		<a href="">Eric S. Raymond</a>

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