#13362: GHC first generation of GC to be as large as largest cache size by default -------------------------------------+------------------------------------- Reporter: varosi | Owner: (none) Type: feature request | Status: new Priority: normal | Milestone: 8.6.1 Component: Runtime System | Version: 8.0.2 Resolution: | Keywords: numa cache gc | newcomers Operating System: Unknown/Multiple | Architecture: Type of failure: Runtime | Unknown/Multiple performance bug | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by klapaucius): Stephen M Blackburn, Perry Cheng, Kathryn S McKinley - Myths and Realities: The Performance Impact of Garbage Collection p. 10 5.4.5 Sizing the nursery "Figure 4(a) shows a small improvement with larger nurseries in mutator performance due to fewer L2 (Figure 4(e)) and TLB misses (Figure 4(f)). However, the difference in GC time dominates: smaller nurseries demand more frequent collection and thus a substantially higher load. We measured the fixed overhead of each collection <...> The garbage collection cost tapers off between 4MB and 8MB as the fixed collection costs become insignificant. These results debunk the myth that the nursery size should be matched to the L2 cache size (512KB on all three architectures)." -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13362#comment:6 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler