I'd like to share some thoughts on improving D's GC, nothing radically
different though.
A few observations
- Pause times seem to be a much bigger problem than CPU usage or memory
bandwith. Focus on reducing the pause times.
- The GC code is already fairly optimized, so there is a very low
profitability in small-scale code optimizations. Improve the algorithms
not the code.
- The current GC code is not hackable. First rewrite then improve.
and corresponding ideas.
- Marking could be parallelized, sweeping should be done in the
background, GC could serve allocations during sweep from a separate pool
(e.g. thread-local).
- The current GC does a lot of bookkeeping work due to how the pools are
organized (heterogeneous bin sizes). I suspect (but don't know) that
there are big gains in organizing this differently.
- A testable and more modular rewrite (using recent D practices) would
encourage more contribution and is necessary for experimentation.
-Martin
