On 8 June 2018 at 00:33, Evan Laforge <qdun...@gmail.com> wrote: > On Thu, Jun 7, 2018 at 2:48 PM, Bartosz Nitka <nite...@gmail.com> wrote: > > What version of GHC are you using? > > There have been some significant improvements like > > https://phabricator.haskell.org/rGHCb8fec6950ad99cbf11cd22698b > 8d5ab35afb828f, > > that only just made it into GHC 8.4. > > I did in fact notice a very nice speedup in 8.4, this explains it. > Finally I know who to thank for it! Thank you very much for that fix, > it really makes a difference. > > Are there more goodies in the 8.0.2 facebook branch, or have they all > made it into 8.4? > > As loaded modules seem to consume a lot of memory, I've considered > trying GHC.Compact on them, but haven't looked into what that would > entail. Have you considered something like that? >
I think I looked into this and found that it wasn't going to be easy, but I forget exactly why. Off the top of my head: - you can't compact mutable things: perhaps the FastString table would give us problems here - there is lots of deliberate laziness to support demand-loading of interface files, compaction would force all of it - you can't compact functions, so if there are any functions in ModIface or ModDetails we would have to avoid compacting those parts of the structure somehow - there are cycles and sharing in these structures so we would need to use the more expensive compaction method that keeps a hash table, which is 10x slower than cheap compaction Probably worth looking into to find out exactly what the problems are though. Cheers Simon > _______________________________________________ > ghc-devs mailing list > ghc-devs@haskell.org > http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs >
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