On Aug 24, 2010, at 10:46 AM, Matthias Felleisen wrote: > (I don't quite understand why there's no extra cost for the second access, > but I'll think about it and figure it out.)
If I understand things correctly, the short answer is "fancy hardware." The page is marked as read-only in the MMU, so a write incurs a page fault. The page fault is trapped by the GC, which records the page in a table of "written-to pages", marks it read-write in the MMU, and continues the program. Now, any write to that page is just like a write to anywhere in memory, but the GC knows to scan the page. This type of thing is only possible with the support in hardware for these sort of read-only page marks. Do I have it right? Will _________________________________________________ For list-related administrative tasks: http://lists.racket-lang.org/listinfo/dev
