7:14:38hayleySBCL now generates code for the write barrier for generational GC, rather than using memory protection on x86-64 and 64-bit PowerPC, and it is faster than using the memory management unit.
7:19:23hayleyQuoth the Douglas Katzman: "No more spurious tripping of the barrier for storing fixnums. As of now this is a compile-time determination, but it could be made to choose at runtime. We'd have to measure the benefit."
7:20:46hayley...and using instructions to mark cards should result in mprotect() being called less often, and the TLB should be utilized better.
7:21:02beachAh, yes, there is that. Compiler type inference and other information can elide the barriers, but that's not generally possible with memory protection.