[project @ 2006-01-17 16:13:18 by simonmar]
Improve the GC behaviour of IORefs (see Ticket #650).
This is a small change to the way IORefs interact with the GC, which
should improve GC performance for programs with plenty of IORefs.
Previously we had a single closure type for mutable variables,
MUT_VAR. Mutable variables were *always* on the mutable list in older
generations, and always traversed on every GC.
Now, we have two closure types: MUT_VAR_CLEAN and MUT_VAR_DIRTY. The
latter is on the mutable list, but the former is not. (NB. this
differs from MUT_ARR_PTRS_CLEAN and MUT_ARR_PTRS_DIRTY, both of which
are on the mutable list). writeMutVar# now implements a write
barrier, by calling dirty_MUT_VAR() in the runtime, that does the
necessary modification of MUT_VAR_CLEAN into MUT_VAR_DIRY, and adding
to the mutable list if necessary.
This results in some pretty dramatic speedups for GHC itself. I've
just measureed a 30% overall speedup compiling a 31-module program
(anna) with the default heap settings :-D
17 files changed: