[GHC] #8173: GHC uses nub

Kim-Ee Yeoh ky3 at atamo.com
Fri Sep 27 20:56:41 UTC 2013

On Fri, Sep 27, 2013 at 8:14 PM, GHC <ghc-devs at haskell.org> wrote:

> A 5% improvement in compile time is remarkable, if it's true.  Great!  But
>  I'm always worried about the noise in compile times measured in seconds.

Does anyone else think the noise in runtimes is alarming considering that
the following is the fib-analysis of /binary-identical/ programs?

>              Min          -0.1%     -0.0%    -25.4%    -32.2%     -1.3%
>             Max          +0.1%     +0.0%    +19.0%    +22.2%    +10.0%

Shouldn't we find an explanation for this before believing the compile time
numbers? What would cause these wide swings on the benchmarking machine?

p.s. For the record: Should do more rigorous statistical testing instead of
naive percentages, yes?

-- Kim-Ee
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