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Programming Considered Harmful

Project: Linux kernel, but with general application

I recently came across a statement on LKML:

> Reviewed by:

I'm not looking for reviews - I'm looking for testers.

As an engineer, this struck me as fundamentally wrong. The ensuring discussion over whether the definition of "free of known issues" meant that the reviewer needed to apply and test the patch was not very rewarding.

In the discussion, the academic peer review model was cited as the reason that reviewers don't need to test the code they review - reading the change is enough to find all known problems. My response was that software engineering code review requires the reveiwer to perform due diligence and that implies a reviewer must apply, test and verifying the code under review. These are very different views on what is supposedly a well defined process.

A further commenter quoted Dijkstra, mocking my views on software engineering process:

'If you carefully read its literature and analyse what its devotees
actually do, you will discover that software engineering has accepted as
its charter "How to program if you cannot."'

During this talk, I will demonstrate that humans cannot Program. There is evidence *everywhere* that we fail badly at Programming and we repeatedly demonstrate that our attempts to Program don't improve as complexity increases. Using examples from the Linux Kernel, I'll state my case for why I think we should be engineering complex software rather than Programming, and how that impacts on our code design and review processes.

Dave Chinner

Dave is the current XFS maintainer. He is currently employeed by Red Hat and spends most of his time developing new filesystem and storage features. He has been a XFS developer since 2004, and worked on the linux kernel since 2005. He has worked on machines of all sizes - from 2000 CPU machines used in the HPC environment to tiny, highly networked embedded systems in the industrial control industry.

In his spare time, Dave builds and races cars and tries to teach his dogs not to bark at the postman....