Remember what I said before#

Thu Jan 1 15:32:27 2004

Remember what I said before Christmas about GC frobbing? With the new simpler region allocation policy described there, but no changes to static space usage :

* (time (dotimes (i 400) (gc)))

Evaluation took:
                 30.413 seconds of real time
                 30.354383 seconds of user run time
                 0.058991 seconds of system run time
                 0 page faults and
                 4939776 bytes consed.
NIL

and in fact we can easily double that again by disabling the check for read-only objects and dumping everything in static space, so it looks like the write barrier stuff does make a difference. So why is CMUCL doing in 13 seconds what takes us 30 (the easy answer is "it has a better object/region allocation policy", obviously, but better why?) and how much faster would it be if it were also to remove purify-into-static-space?

In happier news, while thinking about tidying up today I found a Brian Aldiss novel I apparently haven't read yet.