When there's talk of making sure the GC doesn't take up more than 10ms out of every 50ms, this is only when the GC is actually happening and not during regular running, right?
I think it means that GC will never run for a total of more than 10ms during any 50ms span. It doesn't mean GC would take 20% of total program runtime, except in worst cases. it means that GC will run often and concurrently enough that it won't "stop the world" too long.
