[Agda] Agda speed in Ubuntu

[Martin Escardo]

I decided to do something naughty.

I copied the tree .cabal from Ubuntu 16.04 to 18.04, given that both run 
ghc 8.0.2, and given that I kept my fingers crossed.

Amazingly, now I can run Agda in 18.04 at the same faster speed as in 
16.04. I have little clue of what is going on.

I tested this in three machines running 18.04. All of them get the 
speed-up reported below.

Martin

On 02/08/2019 20:17, Martin Escardo wrote:
> I accidentally discovered the following (because I booted in an old 
> partition to try to find a file, and then kept working on that partition):
> 
> A certain Agda file type checks in a core i5 Dell laptop 7th generation
> 
>   * In 70 seconds in Ubuntu 18.04 LTS
>   * In 50 seconds in Ubuntu 16.04 LTS
> 
> I couldn't believe this, and so I tested this in a core i5 HP laptop 6th 
> generation. The results where, respectively,
> 
>    * 70+delta
>    * 50+delta'
> 
> with the deltas < 3sec.
> 
> Of course we can try to blame the Intel bugs and their fixes for that. 
> But, still, both 16.04 and 18.04 are long-term support versions and are 
> supposed to incorporate the fixes.
> 
> In the four 2x2 cases, Haskell 8.0.2 and Agda 2.6.0.1 are used. Also, in 
> both cases nothing else is running in user space.
> 
> Can anybody reproduce this?
> 
> This is a significant difference: 50/70 is 70% of the time in 16.04. Way 
> faster.
> 
> Martin
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-- 
Martin Escardo
http://www.cs.bham.ac.uk/~mhe