nofib comparisons between 7.0.4, 7.4.2, 7.6.1, and 7.6.2

[Austin Seipp]

I'm +1 for this. Eyal Lotem and I were just discussing this on IRC a
few minutes ago, and he suffered a rather large (~25%) performance hit
when upgrading to 7.6.1, which is unfortunate.

Committers are typically very good about recording nofib results in
their commit and being performance-courteous, but I'm not sure there's
ever been a longer-scale view of GHC performance over multiple
releases like this - or even a few months. At least not recently. On
top of that, his application was a type checker, which may certainly
stress different performance points than what nofib might. Once we get
performance bots set up, I've got a small set of machines I'm willing
to throw at it.

Thanks for the results, Johan!

On Mon, Feb 4, 2013 at 4:33 PM, Johan Tibell <johan.tibell at gmail.com> wrote:
> Hi all,
>
> I haven't had much time to do performance tzar work yet, but I did run nofib
> on the last few GHC releases to see the current trend. The benchmarks where
> run on my 64-bit Core i7-3770 @ 3.40GHz Linux machine. Here are the results:
>
> 7.0.4 to 7.4.2:
>
> --------------------------------------------------------------------------------
>         Program           Size    Allocs   Runtime   Elapsed  TotalMem
> --------------------------------------------------------------------------------
>             Min          -1.6%    -57.3%    -39.1%    -36.4%    -25.0%
>             Max         +21.5%   +121.5%    +24.5%    +25.4%   +300.0%
>  Geometric Mean          +8.5%     -0.7%     -7.1%     -5.2%     +2.0%
>
> The big loser here in terms of runtime is "kahan", which I added to test
> tight loops involving unboxed arrays and floating point arithmetic. I
> believe there was a regression in fromIntegral RULES during this release,
> which meant that some conversions between fixed-width types went via
> Integer, causing unnecessary allocation.
>
> 7.4.2 to 7.6.1:
>
> --------------------------------------------------------------------------------
>         Program           Size    Allocs   Runtime   Elapsed  TotalMem
> --------------------------------------------------------------------------------
>             Min          -5.1%    -23.8%    -11.8%    -12.9%    -50.0%
>             Max          +5.3%   +225.5%     +7.2%     +8.8%   +200.0%
>  Geometric Mean          -0.4%     +2.1%     +0.3%     +0.2%     +0.7%
>
> The biggest loser here in terms of runtime is "integrate". I haven't looked
> into why yet.
>
> 7.6.1 to 7.6.2:
>
> --------------------------------------------------------------------------------
>         Program           Size    Allocs   Runtime   Elapsed  TotalMem
> --------------------------------------------------------------------------------
>             Min          -2.9%     +0.0%     -4.8%     -4.4%     -1.9%
>             Max          +0.0%     +1.0%     +4.5%     +6.4%    +20.8%
>  Geometric Mean          -1.7%     +0.0%     +0.1%     +0.3%     +0.2%
>
> I have two takeaways:
>
>  * It's worthwhile running nofib before releases as it does find some
> programs that regressed.
>  * There are some other regressions out there (i.e. in code on Hackage) that
> aren't reflected here, suggesting that we need to add more programs to
> nofib.
>
> Cheers,
> Johan
>
>
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-- 
Regards,
Austin