GHC build time graphs

[Karel Gardas]

On 01/28/16 11:34 PM, Ben Gamari wrote:
> Joachim Breitner <mail at joachim-breitner.de> writes:
>
>> Hi Oleg,
>>
>> Am Freitag, den 29.01.2016, 00:22 +0200 schrieb Oleg Grenrus:
>>> Is the same compiler used to build HEAD and 7.10,1?
>>
>> Good call. In fact, no: 7.10.1 is built with 7.6.3, while HEAD is built
>> with 7.10.3.
>>
>> Anthony’s link, i.e.
>> https://perf.haskell.org/ghc/#compare/ca00def1d7093d6b5b2a937ddfc8a01c152038eb/a496f82d5684f3025a60877600e82f0b29736e85
>> has links to the build logs of either build; there I could find that information.
>>
>> That might be (part) of the problem. But if it is, it is even worse, as
>> it would mean not only building the compiler got slower, but the
>> compiler itself...
>>
> I can verify that the build itself is indeed slower. Validating the
> current state of ghc-7.10 takes 19 minutes, whereas ghc-8.0 takes 25.5
> minutes. This isn't entirely unexpected but the change is quite a bit
> larger than I had thought. It would be nice to know which commits are
> responsible.

btw, just recent experience on ARM64 (X-gene board):

bootstrapping 7.10.1 with 7.6.x took: ~120 minutes
bootstrapping 8.0.1 RC2 with 7.10.1 took: ~446 minutes

both run as: ./configure; time make -j8

although board is shared I've tried to look at it from time to time and 
have not observed anyone else there so I can assume this is indeed GHC 
slowness on unregisterised -fvia-C ports...

Karel