#7662: Improve GC of mutable objects ---------------------------------+------------------------------------------ Reporter: ezyang | Owner: Type: feature request | Status: new Priority: normal | Milestone: _|_ Component: Runtime System | Version: 7.7 Keywords: | Os: Unknown/Multiple Architecture: Unknown/Multiple | Failure: None/Unknown Difficulty: Unknown | Testcase: Blockedby: | Blocking: Related: | ---------------------------------+------------------------------------------ Comment(by simonmar): I wanted to record an idea that occurred to me: if we were to switch to a mark/sweep (probably mark-region, e.g. Immix) collection for the old generation, which is something I've been wanting to try for some time, then it gives us a way to do card marking. The idea is to retain the bitmap after GC, and use it to find the live objects when sweeping a marked card. The bitmap costs ~3% extra heap size on a 32-bit machine, half that on 64-bits. I'm quite optimistic that mark-region would be a win, and furthermore, because mark/sweep is non-destructive, it could be done incrementally, or concurrently with the mutator (you have to be careful about mutation, but the write-barrier techniques for doing this are well known). The idea is that going incremental or concurrent would improve pause times. -- Ticket URL: http://hackage.haskell.org/trac/ghc/ticket/7662#comment:4 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler