#1600: Optimisation: CPR the results of IO -------------------------------------+------------------------------------- Reporter: simonmar | Owner: nomeata Type: task | Status: new Priority: lowest | Milestone: 7.6.2 Component: Compiler | Version: 6.6.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Unknown/Multiple Type of failure: Runtime | Difficulty: Moderate (less performance bug | than a day) Test Case: | Blocked By: Blocking: | Related Tickets: #8598 -------------------------------------+------------------------------------- Comment (by nomeata): Bummer. While finding out what happened to `wave4main`, I noticed that I introduced a bug (well, imprecision) where `Converges` information was lost. This prevented nested CPR in `wave4main`, and everything looked good. Fixing that bug gives us back the +11.3% for `wave4main`, and also a +0.2% for `scs`. So it remains all very heuristical... The change in `scs` is hard to pin-point, as there is quite a bit of CPR’ing going on which moves allocations between different ticky-ticky- counters. But in the summary, we see an increase in `ALLOC_FUN_gds` again, and there are `$wgo` popping up where there were none, so this indicates lost join points. (Also interesting: `ALLOC_CON_ctr` goes up, but `ALLOC_CON_gds` goes down.) -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/1600#comment:39 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler