slow execution of built executables on a Mac

[Richard Eisenberg]

> On Oct 26, 2018, at 5:02 PM, Carter Schonwald <carter.schonwald at gmail.com> wrote:
> 
> are you setting the intree gmp flag? and/or  dont have gmp the library installed? maybe your ghc is using integer simple!

Intriguing possibility. I haven't done anything to install gmp. I'm now at home, away from this machine, but I'll try this next week. I have a hunch you're right.

Perhaps we should have a warning when this is the case?

> 
> theory two: dont set -j greater than about 8 or perhaps 16? (some parts of ghc are slower on too paralle a setup?)

I'm at -j5, so this isn't the problem.
> 
> you could also look at system monitor to see if your'e being IO bound or memory or CPU bound

I tried this earlier, and it looked like I wasn't CPU-bound. I suspected a slow SSD somehow (if that's even possible). But watching the build this morning showed me that stage 1 is snappy while later work isn't, so that made me doubt my earlier guess. And installing the 6GB of LaTeX wasn't unduly slow, either.

> (possible failure siutation: the repo is under dropbox or something and dropbox is eating your memory bandwidth trying to sync stuff?)

Thanks for the idea, but I know to keep GHC away from Dropbox. :)

I'll give 90% confidence on the gmp thing.

Thanks!
Richard