With UseNUMA we prescribe the OS to allocate the pages round-robin in the old gen. But the default expansion rate is quite low (128K in 32bit, 167K in 64bit), even less than a typical large page (in this case the expansion delta is rounded to the size of the page). This renders the RR allocation attribute useless, because we ask the OS to do it for a single page. The solution is to increase the expansion rate when UseNUMA is specified. Also, we should make sure that the delta is not less than page_size * lgroup_num.