On Tuesday, 27 May 2014 at 17:08:04 UTC, Etienne wrote:
The GC could be optimized under x86_64, with 18,446,744,073,709,551,615 possible values you don't exactly have any computers with 18 exabytes (18,000 petabytes) of memory. This is a lot of wasted space that could be used to make the GC lookups at O(1) speed with parallel collection
That is probably true. If you also limit GC to class types and ban internal pointers you probably could get a decent speedup.
Another optimization is to make sure that all GC pointers are clustered on the same cacheline, for objects with inheritance this is a challenge. An unorthodox solution would be to place all gc pointers at a negative offset in the object instance. I believe a single cacheline can fit 8 pointers, so careful clustering could probably cut the amount of scanned memory by a significant amount. 50%?
