Use work-stealing for load-balancing in the GC
New flag: "+RTS -qb" disables load-balancing in the parallel GC
(though this is subject to change, I think we will probably want to do
something more automatic before releasing this).
To get the "PARGC3" configuration described in the "Runtime support
for Multicore Haskell" paper, use "+RTS -qg0 -qb -RTS".
The main advantage of this is that it allows us to easily disable
load-balancing altogether, which turns out to be important in parallel
programs. Maintaining locality is sometimes more important that
spreading the work out in parallel GC. There is a side benefit in
that the parallel GC should have improved locality even when
load-balancing, because each processor prefers to take work from its
own queue before stealing from others.
13 files changed: