#8732: Global big object heap allocator lock causes contention --------------------------------------------+------------------------------ Reporter: tibbe | Owner: simonmar Type: bug | Status: new Priority: normal | Milestone: 7.10.1 Component: Runtime System | Version: 7.6.3 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Runtime performance bug | Unknown/Multiple Test Case: | Difficulty: Unknown Blocking: | Blocked By: | Related Tickets: --------------------------------------------+------------------------------ Comment (by simonmar): I don't really understand why in mighty he couldn't just re-use the same block. I'm kind of surprised that this is a bottleneck, and I think it needs more investigation. We only take the lock for large objects, so typically there's going to be a lot of computation going on per allocation. I suppose if it really is a problem then we could just have a per-thread block pool at the granularity of a megablock to avoid fragmentation issues. We just push the global lock back to the megablock free list. This has the danger that we might have a lot of free blocks owned by one thread that don't get used, though, so we might want to redistribute the free blocks at GC. Things start to get annoyingly complicated. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8732#comment:9 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler