Function GC_set_allocd_bytes_per_finalizer 

pub unsafe extern "C" fn GC_set_allocd_bytes_per_finalizer(
    arg1: GC_word,
)

Set/get the minimum value of the ratio of allocated bytes since garbage collection to the amount of finalizers created since that collection (so value is greater than GC_bytes_allocd / (GC_fo_entries - last_fo_entries)) which triggers the collection instead heap expansion. The value has no effect in the collector incremental mode. The default value is 10000 unless GC_ALLOCD_BYTES_PER_FINALIZER macro with a custom value is defined to build the collector. The default value might be not the right choice for clients where e.g. most objects have a finalizer. Zero value effectively disables taking amount of finalizers in the decision whether to collect or not. The functions do not use any synchronization.