Re: nofib comparisons between 7.0.4, 7.4.2, 7.6.1, and 7.6.2

We have some benchmarks for Cloud Haskell and its underlying network-transport infrastructure that I'm in the process of trying to automate. I'd be very interested to see how these fare against various GHC releases, though I suspect we'll have to tweak the dependencies considerably in order to make the automation happen. I don't know if that fits into the 'other regressions' category or not? Cheers, Tim On 5 Feb 2013, at 14:24, Nicolas Frisby wrote:

I'd like to investigate the "other regressions out there".

Do you have more info? Perhaps a list? Maybe even benchmarking code?

Thanks.

On Tue, Feb 5, 2013 at 4:22 AM, Austin Seipp wrote: 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 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

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