Disclaimer

The content of this blog is my personal opinion only. Although I am an employee - currently of Imagination Technologies's MIPS group, in the past of other companies such as Intellectual Ventures, Intel, AMD, Motorola, and Gould - I reveal this only so that the reader may account for any possible bias I may have towards my employer's products. The statements I make here in no way represent my employer's position, nor am I authorized to speak on behalf of my employer. In fact, this posting may not even represent my personal opinion, since occasionally I play devil's advocate.

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Wednesday, November 16, 2011

Shared libraries and data deduplication

People have talked about the advantages of shared libraries: reducing virtual memory requirements, reducing disk space requirements, etc, because of sharing.

Here's a thought: Q: if we had truly ubiquitous data deduplication, what would be the advantages of shared libraries?

A: none of the performance wins through sharing need apply.  Deduplication beats them in a more flexible, more abstract, way.

(Of course, we do not have truly ubiquitous deduplication. And it usually requires things to be block or file aligned.)

This leaves the only fundamental advantage of shared librares

  • the fact that you can effect a ubiquitous change by updating a shared library.
Which is also their fundamental disadvantage.  You can propagate a bug fix.  But you can also propagate bugs.

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