11.4.5 Tuning the GC

As in LispWorks 4.x, the main tool for tuning the GC is the macro extended-time and periodical calls to room , to see how the system behaves.

In the output of (room t) , the allocation in each generation is presented according to the allocation type, which may be useful to decide on possible tuning.

(extended-time forms ) outputs the time spent in garbage collection, whether automatic or called explicitly. The time is shown according to the maximum generation number that was collected and to whether it was a standard garbage collection (automatic and calls to gc-generation ) or a marking garbage collection (calls to sys:marking-gc ).

In addition to room and extended-time , there are also the functions sys:count-gen-num-allocation , sys:gen-num-segments-fragmentation-state , and sys:set-automatic-gc-callback . These function can be used to collect information about automatic garbage collection operations. Interface for tuning the GC

LispWorks User Guide - 11 Mar 2008